distribution system capability statement - mzec.nama.om · distribution system capability statement...

DISTRIBUTION SYSTEM

CAPABILITY

STATEMENT [Document subtitle]

Abstract [Draw your reader in with an engaging abstract. It is typically a short summary of the

document. When you’re ready to add your content, just click here and start typing.]

Distribution System

Capability Statement

2018-2020

إحدى شركات مجموعة نماء

Member of Nama Group

Distribution System Capability Statement 2018-2020

Mazoon Electricity Company SAOC Page | i

20

18

-

2

02

0

Foreword

Although every effort has been made to ensure the accuracy of the data provided in this statement,

Mazoon Electricity Company SOAC (MZEC) does not accept any liability for the accuracy of the

information contained herein, and in particular neither MZEC nor its directors or its employees shall

be under any liability for any misstatement or opinion on which the recipient of this statement relies

or seeks to rely.

No part of this Statement may be reproduced, stored in a retrieval system, transmitted or further

distributed in any form or means electronic, mechanical, photocopying, recording or otherwise for

any purpose other than with the written permission of MZEC.


Mazoon Electricity Company SAOC Page | ii

20

18

-

2

02

0

Company Profile

The electricity sector in the Sultanate of Oman has been extensively restructured following the

implementation of the law for the regulation and privatization of the electricity and related water

sector ("The Sector Law"). The Sector Law was promulgated by Royal Decree 78/2004 on 1 August

2004. The law provided for the unbundling of the electricity and related water activities previously

undertaken by the Ministry of Housing, Electricity and Water (MHEW).

A number of successor companies are authorized by licenses issued by the Authority for Electricity

Regulation, Oman to undertake certain regulated activities.

Mazoon Electricity Company SAOC (MZEC) is one of Nama Groups and is authorized to undertake

the regulated activities of distribution and supply within the authorized area stipulated in its License.

It serves a large supply area of almost 75000 km2 in the north-east corner of Oman. MZEC’s supply

area is split into four governorates which are Al Dakhilyiah (to the central-north of Oman), North Al

Sharqiyah and South Al Sharqiyah (the coastal region to the Eastern part of Oman) and South Al

Batinah and Wilayat of Suwaiq (the coastal region to the north-east of Oman). In this statement the

four governorates will be considered as three supply regions as following: Al Dakhilyiah, Al Sharqiyah

which consists of South Al Sharqiyah Governorate and North Al Sharqiyah Governorate and South

Batinah. Among the Four governorates, South Al Batinah Governorate has the highest number of

customer accounts with estimated supply area of 6260 km2 followed by Al Dakhilyiah with an

estimated supply of 31900 km2 with the second highest number of customer accounts. South Al

Sharqiyah Governorate and North Al Sharqiyah Governorate are the biggest among the four supply

areas with an estimated supply area of 37674 km2 and has the lowest number of customer accounts

as shown in the flow chart below.

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

Al Dakhilyiah North AlSharqiyah

South AlSharqiyah

South AlBatinah

MZEC

116,781

73,811 70,279

145,107

405,978

Customers Account


Mazoon Electricity Company SAOC Page | iii

20

18

-

2

02

0

Table of Contents

Foreword ............................................................................................................................................. Company Profile .............................................................................................................................. ii

Introduction ...................................................................................................................................... 1 I Purpose of Statement .............................................................................................................. 1

II Content of Statement .............................................................................................................. 1 IV Contact details for further information............................................................................. 2

Summary Information .................................................................................................................... 3 1. Design Philosophies and Practices ....................................................................................... 3

1.1 Background ............................................................................................................................ 3 1.2 Operational Environment ................................................................................................... 3 1.3 Technical, Design and Operational Criteria .................................................................. 3

1.3.1 Voltage regulation ......................................................................................................... 3 1.3.2 Frequency deviations .................................................................................................. 4

1.3.3 Voltage waveform quality ........................................................................................... 4 1.3.4 Voltage fluctuations ..................................................................................................... 4

1.3.5 Auto-reclosing and single phase Protection Operation ..................................... 4

1.4 Technical standards applying to Distribution System Users ................................... 5 1.4.1 Specific design and performance standards ........................................................ 5

1.4.1.1 Specification of apparatus and Plant ............................................................... 5

1.4.1.2 Earthing .................................................................................................................... 6

1.4.1.3 Voltage control and regulation .......................................................................... 6 1.4.1.4 Protection................................................................................................................. 6

1.4.1.5 Superimposed signals .......................................................................................... 7

1.5 General requirements for Connection ............................................................................ 7 1.5.1 Declaration of Demand characteristics ................................................................... 7

1.5.1.1 Supplies at Low Voltage ...................................................................................... 7 1.5.1.2 Supplies other than at Low Voltage .................................................................. 7

1.5.2 Connection arrangements .......................................................................................... 8 1.5.3 Electrical Delivery Points ............................................................................................ 8

1.5.4 Communications ........................................................................................................... 8

1.6 Technical requirements for Connections ...................................................................... 9 1.6.1 Apparatus and Plant at the ownership boundary................................................. 9

1.6.2 Protection requirements ............................................................................................. 9 1.6.3 Earthing ........................................................................................................................... 9

1.6.4 Fault level considerations .......................................................................................... 9 1.6.5 Capacitive and inductive effects ............................................................................... 9

1.6.6 Telemetry ....................................................................................................................... 10

1.7 Requirements for Embedded Gensets ......................................................................... 10 1.7.1 General requirements ................................................................................................ 10

1.7.2 Provision of information ........................................................................................... 10 1.7.3 Information required from all Embedded Gensets ............................................ 11

1.7.4 Additional information required from some Embedded Gensets .................. 11

1.7.5 Technical requirements ............................................................................................. 11

1.7.5.1 Genset performance requirements ..................................................................... 11

1.7.5.2 Control arrangements ............................................................................................ 12 1.7.5.3 Coordinating with existing protection .................................................................. 12

1.7.5.4 Islanding ................................................................................................................. 12 1.7.5.5 Black Start capability .......................................................................................... 13


Mazoon Electricity Company SAOC Page | iv

20

18

-

2

02

0

1.7.5.6 Genset commissioning tests ............................................................................ 13

2. The 33 kV System ..................................................................................................................... 13 2.1 System Configuration ....................................................................................................... 13

2.2 System Security .................................................................................................................. 14 2.3 Selection and Application of Plant ................................................................................ 14

2.3.1 Transformers ................................................................................................................ 14

2.3.2 Switchgear .................................................................................................................... 14 2.3.3 Overhead Lines ............................................................................................................ 15

2.3.4 Underground Cables .................................................................................................. 15 2.3.5 Short Circuit Levels .................................................................................................... 15

2.3.6 Protection ...................................................................................................................... 15

3. The 11 kV System ..................................................................................................................... 15 3.1 System Configuration ....................................................................................................... 15

3.2 System Security .................................................................................................................. 16 3.3 Selection and Application of Plant ................................................................................ 16

3.3.1 Distribution Substations ........................................................................................... 16

3.3.2 Overhead lines ............................................................................................................. 16

3.3.3 Underground Cables .................................................................................................. 17 3.3.4 Short Circuit Levels .................................................................................................... 17 3.3.5 Protection ...................................................................................................................... 17

4. The Low Voltage System ........................................................................................................ 17

4.1 System Configuration ....................................................................................................... 17

4.3 Selection and Application of plant................................................................................. 17 4.3.1 Distribution Substations ........................................................................................... 17

4.3.2 Overhead Lines ............................................................................................................ 18

4.3.3 Underground Cables .................................................................................................. 18 4.3.4 Protection ...................................................................................................................... 18

5. Operating Voltage ..................................................................................................................... 18 6. Load Management Areas ........................................................................................................ 18

7. Other Interconnected Networks ............................................................................................ 18 8. The 33 kV System Load Flow Study .................................................................................... 19

8.1 Introduction .......................................................................................................................... 19 8.2 Purpose of the Study ......................................................................................................... 19

8.3 The 33 kV Distribution Network ...................................................................................... 19

8.4 The Load Flow Analysis ................................................................................................... 20 8.5 Presentation of Results and Single Line Diagrams for the Years 2018-2020 .... 20

9. The 33 kV Short Circuit Analysis .......................................................................................... 20 10. Voltages Non Compliance .................................................................................................... 21

11. Distribution System Security Standards (DSSS) ........................................................... 21 12. Demand Forecast ................................................................................................................... 22

12.1 Introduction ....................................................................................................................... 23

12.2 Load Curves....................................................................................................................... 24 12.3 Demand forecast Methodology .................................................................................... 26

13. Future System Development Projects .............................................................................. 29

14. Assessment of 33 KV Technical Losses .......................................................................... 37

15. Network Suitability for New Connections ........................................................................ 37

16. Constraints ............................................................................................................................... 38


Mazoon Electricity Company SAOC Page | v

20

18

-

2

02

0

Lists of Tables

Table 1: Voltage Regulation ........................................................................................................................................... 4

Table 2: Number of 33/11.5 kV transformers up to September 2017 .................................................................... 14

Table 3: Current Ratings of Bus Bar, Bus-section, Transformer and Feeder Bays ............................................ 15

Table 4: Number of distribution transformer until September 2017 ........................................................................ 16

Table 5: MZEC’s operating voltages ........................................................................................................................... 18

Table 6: Distribution System Security Standards ...................................................................................................... 22

Table 7: Peak Demand in MW of Corporate Projects by Customer Category expected in 2018-2020 ............ 28

Table 8: MZEC coincident after diversity and load factor ........................................................................................ 28

Table 9: 33 KV Projects for Al Dakhilyiah 2018-2020............................................................................................... 30

Table 10: 33 KV Projects for South Al Sharqiah 2018-2020 ................................................................................... 31

Table 11: 33 KV Projects for South Batinah 2018-2020 .......................................................................................... 32

Table 12: 33 KV Projects for North Al Sharqiah 2018-2020 .................................................................................... 33

Table 13: Sponsor Project in Al Dakhiyah .................................................................................................................. 34

Table 14: Sponsor Project in South Al Sharqiah ....................................................................................................... 34

Table 15: Sponsor Project in South Batinah ...................................................................................................................... 35

Table 16: Sponsor Project in North Sharqiah ............................................................................................................ 36

Table 17 : MZEC’s Total Demand and 33 KV Network Losses 2018-2020 .......................................................... 37

Lists of Figures

Figure 1: MZEC peak load ............................................................................................................................................ 24

Figure 2: The Load Profile of MZEC ........................................................................................................................... 24

Figure 3: Weekly Load Profile ...................................................................................................................................... 25

Figure 4: MZEC Yearly Load Profile 2016 (Jan-Oct) ................................................................................................ 25


Mazoon Electricity Company SAOC Page | 1

20

18

-

2

02

0

Introduction

I Purpose of Statement This Capability Statement is prepared in accordance with the Distribution & Supply License Condition

32: Distribution System Capability Statement and Clause DPC.4.4 (Three Year Capability

Statement) of the Distribution Planning Code to assist existing and future users of MZEC’s network

in examining opportunities available to them to make new or additional use of the network.

The aim of the Three Year Capability Statement is to:

1) Improve the availability of distribution network information.

2) Furnish developers with sufficient information to carry out initial assessments of network

capability.

3) Inform users of distribution network about development proposals.

II Content of Statement The statement contains information regarding the 33 kV and 11 kV systems and the transformation

level to 11 kV that are owned and operated by MZEC. Some of the requirements for the connection

to the Distribution System derived from the {Distribution Code – Distribution Connection

Conditions Code (DCC)}, design philosophies employed by MZEC, general description of MZEC’s

Distribution System are included in the Summary Information section.

Introduction

An overview of the Long Term Development Statement intended to enable users and potential users

of the network to understand the scope of the information provided and to assess if it would be of

use to them.

Summary Information

This is a general description of the design philosophies and practices appropriate to the whole of the

distribution network.

Load Flow Study of the 33 kV Network

A general and brief description of the load flow study analysis carried on MZEC’s 33 KV network

using ETAP software is presented in this part of the statement.

Short Circuit Study of the 33 kV Network

A brief outlining of the short circuit study analysis results conducted on the 33 KV networks of the

four Governorates are presented.



20

18

-

2

02

0

Voltage Non-Compliance

Non-compliance towards the voltage standards is presented for the 33 kV bus bars at the primary

substations only is addressed in section 10.

Distribution System Security Standards (DSSS)

After the approval of the Distribution System Security Standards in November 2008, compliance with

the planning standards has become a compulsory issue. This is presented in section 11.

Load Curves

Sample graphs of MZEC’s load curve (yearly, weekly and daily) are presented in section 12.

Future System Development Projects

These development statements for the four Governorates Al Dakhilyiah, North Al Sharqiyah, South

Al Sharqiyah and South Al Batinah governorates are presented in a detailed form in section 13.

IV Contact details for further information

Requests for a copy or even copies of this Capability Statement or for assistance in interpretation

and clarification of the information contained in the statement should made to:

Senior Planning & Asset Management Manager

Mazoon Electricity Company SAOC

P.O. Box 1229

P.C. 131, Al-Hamriya

Sultanate of Oman

E-Mail: [email protected]

mailto:[email protected]



20

18

-

2

02

0

Summary Information

1. Design Philosophies and Practices

1.1 Background

Mazoon Electricity Company SAOC (MZEC) has a functional philosophy that underlies the

development of the distribution system at the three voltages 33, 11 and 0.415 kV. This ensures that

the whole distribution system satisfies the following fundamental design criteria throughout the

planning period:

1) Compliance with all legal and statutory requirements,

2) Compliance with all regulatory requirements, including the Grid Code and the Distribution Code,

3) Compliance with all relevant national and international standards,

4) Ability to meet the demands placed upon it in terms of customer requirements, supply

performance (availability and reliability) and supply quality (voltage and waveform quality).

The distribution system must also be capable of being operated, maintained, repaired, extended and

replaced as necessary during its life, without exceeding design levels of risk to the customers it

serves.

1.2 Operational Environment

The distribution system has to be designed such that it is capable of continuous operation under the

range of climatic conditions that can be reasonably expected in the geographic region covered by

MZEC’s distribution system.

1.3 Technical, Design and Operational Criteria

The Distribution System and any Distribution System User Connections to the Distribution System

shall be designed to be consistent with the security requirements of Condition 31 of the Distribution

and Supply License.

MZEC will ensure that the Distribution System complies with the following technical, design and

operational criteria in relation to the part of the Distribution System at the Connection Site with a

Distribution System User.

1.3.1 Voltage regulation

The voltage on the 33 kV and 11 kV sides of Distribution transformers at Connection Sites with

Distribution System Users shall normally be controlled within the limits± 6%of the nominal value.

During some System Disturbances such as where short circuits occurs, the voltage may collapse

transiently to zero at the point of fault until the fault is cleared.

Under fault and circuit switching conditions the 50.00Hz Frequency component of voltage may fall

or rise transiently. The fall or rise in voltage will be affected by the method of earthing of the neutral

point of the Distribution System and this variation in voltage shall be taken into account in selecting

apparatus and Plant from an appropriate specification for installation or Connection to the System.



20

18

-

2

02

0

The voltage at the Consumer’s terminals shall not vary from the System nominal voltage by more

than (see Table 1)

Table 1: Voltage Regulation

Consumers Connected at Nominal Voltage Tolerance

HV 33/11 kV ± 6%

LV 415/240 V ± 6%

1.3.2 Frequency deviations

During normal operating conditions, the nominal System Frequency of the Transmission and

Distribution Systems will be 50.00 Hz and normally will be controlled by Oman Electricity

Transmission Company (OETC) between 49.95Hz and 50.05Hz. During exceptional steady state

conditions, Frequency deviations will not exceed 49.90Hz to 50.10Hz unless disturbed

circumstances prevail. Under disturbed conditions, System Frequency could rise transiently to 51.50

Hz or fall to 48.00 Hz.

1.3.3 Voltage waveform quality

All apparatus and Plant Connected to the Distribution System, and that part of the Distribution

System at each Connection Point, should be capable of withstanding the following distortions of the

voltage waveform in respect of harmonic content and phase unbalance.

The maximum total levels of harmonic distortion on the Distribution System at, 33 kV and 11 kV,

from all sources under both normal, planned outage and fault outage conditions, shall not exceed a

total harmonic distortion of 2.0 % with no individual harmonic greater than 1.5 % unless abnormal

conditions prevail. At LV the maximum total levels of harmonic distortion from all sources shall not

exceed a total harmonic distortion of 2.5 %.

The maximum negative phase sequence component of the phase voltage on the Distribution System

should remain below 1.0 % unless abnormal conditions prevail. A maximum value of 2.0 % is

permitted for phase unbalance.

1.3.4 Voltage fluctuations

Voltage fluctuations arising from fluctuating Demands Connected at a Connection Point to the

Distribution System shall not exceed 1.0% of the voltage level for step changes that may occur

repetitively. Any large voltage excursions other than step changes may be allowed up to a level of

3.0% provided that this does not constitute a risk to the Distribution System or to any Distribution

System User.

1.3.5 Auto-reclosing and single phase Protection Operation

Distribution System Users should be aware that MZEC may use auto-reclosing or sequential

switching features on the Distribution System. MZEC will on request provide details of the auto-



20

18

-

2

02

0

reclosing or sequential switching features in order that the Distribution System User may take this

into account in the design of the User’s Distribution System, including Protection arrangements.

Distribution System Users should be aware that the Protection arrangements on some Distribution

Systems may cause disconnection of one phase or two phases only of a three phase Supply for

certain types of fault.

1.4 Technical standards applying to Distribution System Users

All Distribution System User apparatus and Plant associated with the Connection to the Distribution

System shall comply with the following standards, as applicable (in the following order of

precedence):

(a) Safety Rules;

(b) Oman Electrical Standards (OES), which are such national standards as may be

amended by the Distribution Code Review Panel from time to time and approved by Authority

for Electricity Regulation, Oman “the Authority” or which are imposed under the Sector Law;

(c) The standards and recommendations of the International Standards Organization and the

International Electro technical Commission; and

(d) National standards and codes which are accepted internationally.

Further advice will be made available upon request to MZEC.

In the event that any standard or specification with which a Distribution System User’s Plant and/or

apparatus is required to comply under DCC.5 is amended, MZEC, having consulted with the affected

Distribution System Users, will bring the issues to the Distribution Code Review Panel for

consideration. Following the review, the Distribution Code Review Panel will make a

recommendation to the Authority for approval as to what action, if any, should be taken regarding

compliance.

Where MZEC determines that in order to ensure safe and coordinated Operation of a Distribution

System User’s Plant and/or apparatus with the Distribution System, there is a requirement for

supplemental specifications and/or standards to apply to the design of a Distribution System User’s

Plant and/or apparatus, MZEC shall notify the Distribution System User and the Distribution System

User shall comply with the additional requirements. On request from the Distribution System User,

a Licensed Distributor shall provide reasonable evidence as necessary to demonstrate the need for

the supplemental specifications and/or standards. If a Distribution System User is still not satisfied,

the Distribution System User may refer the issue to the Distribution Code Review Panel for review.

1.4.1 Specific design and performance standards

1.4.1.1 Specification of apparatus and Plant

The specifications of apparatus and Plant shall be such as to permit operation of the Distribution

System within the Safety procedures of MZEC, details of which will be made available by MZEC

upon request.

Apparatus and Plant shall be suitable for use at the operating Frequency, within the intended

operating voltage range and at the design short-circuit rating of the Distribution System to which it is

Connected having due regard to fault carrying capabilities and making and breaking duties. In



20

18

-

2

02

0

appropriate circumstances, MZEC will provide details of the System to which Connection is to be

made.

Apparatus and Plant shall be operated within the thermal rating conditions contained in the

appropriate standards, specifications, and other relevant publications, taking into account the

intended use. Upon request, MZEC will make such information available.

1.4.1.2 Earthing

MZEC can advise on the method of earthing of the Distribution System, for example, whether it is

connected solidly to Earth or through impedance. The specification of associated apparatus and

Plant of the Distribution System User shall meet the voltages that will be imposed on the apparatus

and Plant as a result of the method of earthing. The methods of earthing should comply with the

requirements of Oman Electrical Standards.

Distribution System Users shall take precautions to limit the occurrence and effects of circulating

currents in respect of the neutral points connected with earth where there is more than one source

of electricity.

1.4.1.3 Voltage control and regulation

Any extension or Connection to the Distribution System shall be designed in such a way that it does

not adversely affect the voltage control employed by MZEC on the Distribution System. MZEC if

requested by the Distribution System User will make information on the voltage regulation and

control arrangements available.

1.4.1.4 Protection

The Distribution System and the System of any Distribution System User Connected to the

Distribution System shall incorporate protective devices to ensure that apparatus and Plant with

electrical faults are disconnected from the System promptly and that the effects of faults on one

System do not impose unreasonable risks to other Systems.

To ensure satisfactory operation of the Distribution System, Protection Systems, operating times,

discrimination, and sensitivity at the ownership boundary shall be agreed between MZEC and the

System User during the process of application for Connection and may be reviewed from time to

time by MZEC with the agreement of the customer. Back-up Protection by Operation of other circuit

breakers or apparatus and Plant having a similar function must normally be provided, to safeguard

the System against a circuit breaker, or apparatus and Plant having a similar function, failing to

Operate correctly to interrupt fault current on a High Voltage System. During the process of

application for connection, MZEC will advise the Distribution System User if Back-up protection is

not required.

Distribution System Users shall not use protection and associated apparatus and plant to limit the

fault current in feed to the Distribution System, if the failure of that protection and associated

apparatus and plant to operate as intended in the event of a fault, could cause apparatus and plant

owned by MZEC to operate outside its short-circuit rating, unless MZEC should advise otherwise.



20

18

-

2

02

0

1.4.1.5 Superimposed signals

Where Distribution System Users install mains-borne signaling apparatus and plant it shall comply

with European Standard EN50065 as amended from time to time. Prior agreement shall be obtained

in writing from MZEC where a Distribution System User proposes to use such apparatus and plant

that may superimpose signals on the Distribution System.

1.5 General requirements for Connection

DCC.6 ensures that all Distribution System Users of the Distribution System are subject to the same

requirements for connection. DCC.6 specifies the information required from Distribution System

Users by MZEC in order to ensure that adequate technical provision is made for new Supplies or

increases in existing Demand. DCC.6 also applies to Gensets that Operate in parallel with the

Distribution System, where a supply is required from MZEC under normal or Emergency Conditions.

1.5.1 Declaration of Demand characteristics

1.5.1.1 Supplies at Low Voltage

For Supplies at Low Voltage it is possible in most cases to assess whether a proposed Connection

is acceptable, and to determine the necessary Supply arrangements, from analysis of the following

limited data:

(i) Maximum power requirements ( kVA or kW and Power Factor);

(ii) Type and electrical loading of apparatus and Plant to be Connected, e.g. number and

size of motors, electrical cooling arrangements; and

(iii) The date when the Connection is required.

These data requirements will be specified on the appropriate application for Connection form

obtainable from MZEC. Should a preliminary examination of this data indicate that more detailed

information is required then it shall be provided to MZEC upon request if reasonably required.

1.5.1.2 Supplies other than at Low Voltage

For Supplies other than at Low Voltage it may be necessary for the following additional information

to be provided on request:

(i) All types of Demand:

(a) Maximum Distribution System User Active Power requirement (MW);

(b) Maximum and minimum Reactive Power requirements (MVAr);

(c) Type of Demand and control arrangements e.g. controlled rectifier or large motor

drives, type of starter employed;

(d) Maximum Demand on each phase at time of maximum Demand; and

(e) The maximum harmonic currents to be imposed on MZEC Distribution System.

(ii) Fluctuating Demands:

Details of the cyclic variation, and where applicable the duty cycle, of Active Power (and Re-active

Power, if appropriate), in particular:

(a) The rates of change of Active and Reactive Power, both increasing and

decreasing;



20

18

-

2

02

0

(b) The shortest repetitive time interval between fluctuations in Active Power and

Reactive Power; and

(c) The magnitude of the largest step changes in Active Power and Reactive Power,

both increasing and decreasing.

In some cases, more detailed information may need to be provided to permit a full assessment of

the effect of the Demand on the Distribution System. Such information may include an indication of

the pattern of buildup of Demand and a proposed commissioning program. MZEC will specifically

request this information when necessary.

1.5.2 Connection arrangements

The design of Connections between the Distribution System and Distribution System Users shall be

in accordance with the principles set out in the DCC, subject to any modification to which MZEC may

reasonably consent.

During the process of application for Connection MZEC will agree with the Distribution System User

the voltage level to which a Distribution System User will be connected in accordance with its normal

practice for the type of Demand to be supplied. MZEC may on occasion specify a different

Connection voltage from normal in order to avoid potential disturbance caused by the Distribution

System User apparatus to other Distribution System Users of the Distribution System or for other

technical reasons or may agree alternative methods for minimizing the effects of disturbing

Demands.

Before entering into an ECA/ECUOSA it will be necessary for MZEC to be reasonably satisfied that

the Distribution System User’s System at the boundary with the Distribution System will comply with

all appropriate requirements of the Distribution Code.

1.5.3 Electrical Delivery Points

The point or points at which Supply is given or taken will be the Electrical Delivery Points as specified

in the ECA/ECUOSA. For Supplies at Low Voltage the general rule is that the Electrical Delivery

Point will be at the Distribution System User terminals of the Metering System.

For High Voltage Supplies, including Connections between MZEC and Distribution System Users,

and where necessary, bus bar Connected Supplies at Low Voltage, the points of Supply will be the

Electrical Delivery Points as specified in the ECA/ECUOSA. The respective ownership of Plant or

apparatus will be recorded in the ECA/ECUOSA between a MZEC and the Distribution System User

as required. In the absence of a separate agreement between the parties to the contrary,

construction, commissioning, control Operation and maintenance responsibilities follow ownership.

Paragraph DCC.9 specifies responsibilities at the Connection Site.

1.5.4 Communications

Where, for operational reasons, MZEC determines that a means of routine and emergency

communication between MZEC and the Distribution System User is required then the same shall be

provided and maintained by the Distribution System User.



20

18

-

2

02

0

1.6 Technical requirements for Connections

1.6.1 Apparatus and Plant at the ownership boundary

All apparatus and Plant at the ownership boundary shall meet the design principles contained within

DCC.4. Connections for entry to and exit from the Distribution System shall incorporate a means of

disconnection of the installation by MZEC.

1.6.2 Protection requirements

Protection requirements vary widely depending on established practices and the needs of the

particular Distribution System. The basic requirement in all cases is that Distribution System User

arrangements for Protection at the ownership boundary, including types of apparatus and Plant and

Protection settings, must be compatible with standard practices on the Distribution System, as

specified by MZEC during the process of application for Connection. In particular;

(i) Maximum clearance times (from fault current inception to arc extinction) must be within

the limits established by MZEC in accordance with Protection and apparatus and Plant short

circuit rating policy adopted for the Distribution System;

(ii) In Connecting to the Distribution System the Distribution System User should be aware

that auto-reclosing or sequential switching features may be in use on the Distribution System.

MZEC will on request provide details of the auto-reclosing or sequential switching features in

order that the Distribution System User may take this into account in the design of the

Distribution System User System, including Protection arrangements; and

(iii) The Distribution System User should also be aware that the Protection arrangements on

some Distribution Systems, e.g. rural, may cause disconnection of one phase only of a three

phase Supply for certain types of fault.

1.6.3 Earthing

Earthing of that part of the Distribution System User System that is connected to MZEC’s Distribution

System shall comply with the arrangements specified in DCC.5.2.1.

1.6.4 Fault level considerations

The short circuit rating of Distribution System User’s apparatus and Plant at the Connection Point

should be not less than the design fault level of the Distribution System to which it is connected. The

choice of apparatus and Plant for Connection at Low Voltage may take into account attenuation in

the service lines in accordance with Good industry Practice. MZEC in the design of its System will

take into account the contribution to fault level of the Connected System and apparatus.

In order to permit these assessments to be carried out information should be exchanged on

prospective fault power in feed and X/R ratios, where appropriate, at points of entry to and exit from

the Distribution System.

1.6.5 Capacitive and inductive effects

The Distribution System User shall, when applying to make a Connection, provide MZEC with

information as detailed in DCC.7. Details will be required of capacitor banks and reactors connected

at High Voltage which could affect the Distribution System and which it is proposed to Connect if



20

18

-

2

02

0

agreed by MZEC. When requested by MZEC details of distributed circuit capacitance and inductance

shall also be provided. Sufficient detail is required to:

(i) Verify that controlling apparatus and Plant of the Distribution System is suitably rated;

(ii) Show that the performance of the Distribution System will not be impaired; and

(iii) Ensure that arc suppression coils when used by MZEC for System Earthing purposes

are correctly installed and operated.

1.6.6 Telemetry

The Distribution System User should provide such voltage, current, Frequency, Active Power and

Reactive Power pulses and outputs and status points from its System as are considered reasonable

by Licensed Distributors to ensure adequate System monitoring. The telemetry outstation in such a

situation will be provided, installed and maintained by MZEC. Under the requirements of the Grid

Code new CDGensets and Production Facilities will need to provide signals to OETC for monitoring

purposes.

If it is agreed between the parties that MZEC shall control the switchgear on the Distribution System

User’s System MZEC shall install the necessary telecontrol outstation. Notwithstanding the above,

it shall be the responsibility of the Distribution System User to provide the necessary control interface

for the Distribution System User switchgear that is to be controlled.

1.7 Requirements for Embedded Gensets

1.7.1 General requirements

Embedded CDGensets shall comply with the general principles of the Grid Code, subject to the

particular requirements of MZEC necessitated by the adjacent Distribution System conditions, which

will be made known by MZEC during the Connection application process. Copies of data supplied in

accordance with the Grid Code shall be given to MZEC.

1.7.2 Provision of information

Embedded Gensets will fall within three basic classes for which the Power Producer shall provide

the following minimum information to MZEC during the process of Connection application or

otherwise as requested by MZEC. When applying for Connection to the Distribution System Power

Producers shall also refer to DCC.5 and OES. The three basic classes are;

a - Embedded CDGensets (All Gensets with a Registered Capacity of 5MW or greater will be

centrally dispatched);

b - Embedded Gensets Connected at or below 20 kV and with an output not in excess of 5MW;

and

c - Embedded Gensets who are to be connected at Low Voltage and less than 300 kVA in

capacity.

MZEC will use the information provided to model the Distribution System and to decide what method

of Connection will need to be employed and the voltage level at which the Connection should be

made. If MZEC reasonably concludes that the nature of the proposed Connection or changes to an

existing Connection requires more detailed consideration then further information may be requested.

It is unlikely that more information than that specified in DCC.8.3.1 will be required for Embedded

Gensets who are to be connected at Low Voltage and are less than 50 KVA in capacity, or connected

at other than Low Voltage and less than 300 kVA in capacity.



20

18

-

2

02

0

1.7.3 Information required from all Embedded Gensets

Each Power Producer will provide to MZEC information on (a) the Gensets and (b) the proposed

interface arrangements between the Genset and the Distribution System. MZEC may require the

following information before entering into an ECA/ECUOSA to connect any Gensets to the

Distribution System:

Genset data

a Terminal volts; kV

b Rated Capacity; kVA

c Rated Capacity; kW

d Maximum Active Power sent out

Reactive Power requirements (if any);

kwso max

kVAr

e Type of Genset; Synchronous, asynchronous, etc

f Type of prime-mover;

g Anticipated operating regime of Gensets; Continuous, intermittent, peak lopping

h Fault level contribution; kA

I Method of voltage control;

j Generator transformer details; As applicable

k Requirements for top-up Supplies and/or standby Supplies;

Interface arrangements

a The means of Synchronization between MZEC and Distribution System User;

b Details of arrangements for Connecting with earth that part of the User System

Connected to the Distribution System;

c The means of Connection and disconnection which are to be employed;

d Precautions to be taken to ensure the continuance of safe conditions should any

earthed neutral point of the User System Operated at HV become disconnected from

earth;

1.7.4 Additional information required from some Embedded Gensets

MZEC may request the information before entering into an ECA/ECUOSA to connect any Gensets

greater in size than 5 MW or connected at a voltage level above 11 kV onto the Distribution System.

1.7.5 Technical requirements

1.7.5.1 Genset performance requirements

For Embedded CDGensets the electrical parameters required would be those detailed in the Grid

Code.



20

18

-

2

02

0

For Gensets not subject to Central Dispatch the electrical parameters that must be achieved at the

Genset terminals are defined according to the Connection method and will be specified by MZEC

with the offer for Connection. Each Genset or Production Facility must be capable of Supplying its

Registered Capacity within the Total System Frequency range 49.50 to 50.50 Hz. The output power

should not be affected by voltage changes within the permitted operating range.

1.7.5.2 Control arrangements

Licensed Distributors will specify in writing if a continuously acting fast response automatic excitation

control System is required to control the Genset voltage without instability over the entire operating

range of the Genset or Production Facility. This will be dependent on the size and type of Genset or

Production Facility and the part of the Distribution System to which it is connected.

1.7.5.3 Coordinating with existing protection

It will be necessary for the Protection associated with Embedded Gensets to co-ordinate with the

Protection associated with the Distribution System as follows:

(i) For Gensets Connected to the Distribution System the Genset must meet the target

clearance times for fault current interchange with the Distribution System in order to reduce

to a minimum the impact on the Distribution System of faults on circuits owned by Power

Producers. MZEC will ensure that MZEC Protection settings meet its own target clearance

times.

The target clearance times are measured from fault current inception to arc extinction and

will be specified by MZEC to meet the requirements of the relevant part of the Distribution

System.

(ii) The settings of any Protection controlling a circuit breaker or the operating values of any

automatic switching device at any Connection Point with the Distribution System shall be

agreed between MZEC and the Distribution System User in writing during the Connection

consultation process.

The Protection settings or operating values shall not be changed without the written

agreement of MZEC.

(iii) It will be necessary for the Genset Protection to co-ordinate with any auto-reclose policy

specified by MZEC.

(iv) Any Genset or Production Facility Connected to the Distribution System will be required

to withstand, without tripping, the negative phase sequence loading incurred during the

clearance of a close-up phase-to-phase fault by System Backup Protection which will be

within the Plant short time rating on the Distribution System. MZEC will advise the Power

Producer of the expected negative phase sequence loadings during the ECA/ECUOSA

process.

1.7.5.4 Islanding

It is possible that a part of a Distribution System to which Embedded Gensets are connected could,

during Emergency Conditions, become detached from the rest of the Distribution System. MZECshall

decide dependent on local network conditions, if it is desirable for the Embedded Gensets to continue

to Generate onto the islanded Distribution System.



20

18

-

2

02

0

If no facilities exist for the subsequent resynchronization of the islanded section of the Distribution

System with the rest of the Distribution System then the Embedded Genset will under Licensed

Distributor instruction, ensure that the Genset is disconnected for resynchronization.

Under Emergency Conditions there is an expectation that some Gensets will continue to operate

outside the Frequency limits set down in the Grid Code CC.6. However, for Embedded Gensets

Connected to the Distribution System at a voltage level less than 33 kV it is likely that this could

mean Connection within an automatic under-frequency Demand disconnection zone. Consequently,

Embedded Gensets should ensure that all Protection on Gensets should have settings to co-ordinate

with those on the automatic under-frequency Demand disconnection apparatus and Plant that will

be detailed by MZEC on request.

1.7.5.5 Black Start capability

Each Embedded Power Producer shall notify MZEC if its Gensets has a restart capability without

Connection to an external power Supply, unless the Embedded Genset shall have previously notified

OETC accordingly under the Grid Code.

1.7.5.6 Genset commissioning tests

Where Gensets require Connection to the Distribution System in advance of the commissioning date,

for the purposes of testing, the Genset must comply with the requirements of the ECA/ECUOSA.

The Power Producer shall prepare a commissioning program and obtain approval to the program

from MZEC to allow commissioning to be coordinated.

2. The 33 kV System

2.1 System Configuration

The 33 kV System of MZEC serves in a distribution role between the OETC and the 11 kV system

as direct 132/11 kV transformation is not in use. The system consists mainly of 33 kV feeders,

33/11kV primary substations and 33/0.415 kV transformers installed on some feeders where it is not

feasible to develop 11 kV network due to limited amount of demand. The 33 kV feeders emanate

from the 132/33 kV grid stations to supply the 33/11 kV primary substations. Primary substations are

of two types, namely indoor type and outdoor type. Indoor primary substations are mainly of 2x10

MVA and 2x20 MVA with 33 kV outdoor/indoor circuit breakers and 14 panels 11 kV indoor

switchgear. Indoor primary substations are proposed to be constructed during the coming years to

supply highly growing areas. Outdoor primary substations are installed throughout the four

governorates of MZEC in urban and rural areas where demand is normally less than 12 MVA. The

normal practice is to supply each primary substation with two 33 kV feeders; each feeder is feeding

one transformer and serves as an alternative supply for the whole substation in case the other feeder

fails. Along the 33 kV feeders, Tees are used to connect primary substations. The whole network is

interconnected especially at South Al Batinah and Al Dakhilyiah governorate except in few situations,

where radial feeders without interconnections with other feeders feed primary substations.



20

18

-

2

02

0

2.2 System Security

The majority of MZEC’s primary substations are of the standard two transformers type with two

separate 33 kV and 11 kV busbars. In some cases where demand is much less than the capacity of

two transformers, which is normal in remote rural areas, primary substations with only one 33/11 kV

transformer are installed. The 33 kV network is designed and will be developed to meet its customer’s

satisfaction and comply with the Distribution System Security Standards (DSSS).

2.3 Selection and Application of Plant

2.3.1 Transformers

Transformers installed in the 33 kV system are categorized into 33/11.5 kV and 33/0.433 kV.

33/11.5 kV transformers are standard as far as the 33 kV system is concerned. The ratings in use

are 1, 3, 6, 10 and 20 MVA. The 1, 3 and 6 MVA transformers are equipped with Off Load Tap

Changers, whereas 10 and 20 MVA transformers are equipped with On Load Tap Changer. All

transformers comply with the requirements of IEC 76/BSS 171. The temperature rise of winding shall

not exceed 50 Deg. C by resistance of oil, 40 Deg. C by thermometer over an ambient of 50 Deg. C.

The 33/0.433 kV transformers are naturally cooled outdoor oil immersed core type and are complying

with the requirements of IEC 76/BSS 171 except that the temperature rise shall not exceed 50 Deg.

C for winding by resistance and 40 Deg. C for oil by thermometer. The smallest rating in use for this

category is 50 kVA and the highest is 1000 kVA.

Currently, the number of 33/11.5 kV substations and transformers exists in the system up to

September 2017 are shown in Table 2.

Table 2: Number of 33/11.5 kV transformers up to September 2017

Asset Type Quantity Total

North Sharqiyah South

Sharqiyah South Al Batinah

Al Dakhilyiah

20MVA 16 24 75 62 177

10MVA 2 9 7 4 22

6MVA 59 40 73 79 251

3MVA 8 0 7 9 24

2.3.2 Switchgear

The 33 kV indoor switchgear is of single bus bar, totally enclosed metal-clad type with withdraw able

circuit breakers or metal-clad SF6 insulated with vacuum or SF6 circuit breakers. 11 kV and 33 kV

current ratings of the bays are shown in Table 3.



20

18

-

2

02

0

Table 3: Current Ratings of Bus Bar, Bus-section, Transformer and Feeder Bays

Rating 11 kV at Primary substations 33 kV

Bus-bar 2000 A 2000A

Bus-Section 1200 A 1200A

Transformer 1200 A 600A

Feeder 400 A 600A

2.3.3 Overhead Lines

Overhead lines are extensively used due to the rural character of MZEC’s Authorized Area. These

are mainly bare ACSR conductors with conductor sizes of 150 mm2 (wolf) or 200 mm2 (panther) on

wooden and concrete poles supported by post insulators. Up to September 2017 the installed

overhead line hit a total of 3880.2 km.

2.3.4 Underground Cables

Due to the rural area character of MZEC’s Authorized Area, 33 kV underground cables are mainly

used to connect overhead lines with grid stations, connecting some overhead lines with primary

substations, road crossings situations and in urban areas and towns where overhead lines cannot

be installed. The standard size commonly in use is the 3-core 300 mm2 copper XLPE cables. It

conforms to relevant IEC specifications. The use of underground cable increases significantly and

the installed length reached around 1269.3 km in October 2017.

2.3.5 Short Circuit Levels

Switchgear installed on the 33 kV Distribution System will be specified with a three-phase

symmetrical short circuit breaking rating not less than 25 kA at 33 kV for 2x20 MVA substations.

2.3.6 Protection

All items of plant will be covered by systems of the main protection. Distance protection is employed

for overhead line feeders.

3. The 11 kV System


The main purpose of the 11 kV systems is to distribute electricity into and around local urban and

rural areas in an economic, efficient, safe and secure manner whilst meeting the needs of customers.

The general design principle for configuring the distribution system is based on primary substations,

indoor and outdoor with mostly two transformers and 11 kV busbars, providing a continuous firm 11

kV supply. The 11 kV feeders emanate from the 33/11 kV indoor and outdoor primary substations

are mainly overhead lines feeding the distribution transformers. At all indoor primary substations, 11

kV circuit breakers are provided whereas 11 kV Auto-Reclosers are provided at the outdoor primary

substations. Due to the regional character of MZEC’s authorized area, 11 kV underground feeders

are seldom. Interconnections between feeders from the same primary substation or from different



20

18

-

2

02

0

primary substations through Ring Main Units (RMU), Air Break Switches (ABS) and Open Jumpers

are the normal practice.

These 11 kV feeders are normally operated as radial feeders, with the open point selected for ease

of operational access to minimize customer minutes lost, whilst taking account of the need to meet

security requirements and minimize system losses and voltage drops.

3.2 System Security

In order to meet the customer’s expectations and needs, the 11 kV network is designed and will be

developed to meet the obligations set out in the relevant codes and comply with the approved

Distribution System Security Standards.

3.3 Selection and Application of Plant

3.3.1 Distribution Substations

Distribution substations are of two types, ground-mounted and pole-mounted. For ground-mounted

distribution substations, normally one transformer of rated capacity 500 kVA or higher are used,

whereas those transformers with ratings less than 500 kVA are installed on H-Pole structures. Both

types of substations are fed from the 11 kV feeders either directly with jumpers (Pole-Mounted) or

through 11 kV cables (Ground-Mounted). Expulsion fuses are used to protect both types of

substations on the high voltage side and HRC fuses on the low tension side. However Ground-

mounted transformers connected through HFU are protected by HRC fuses of 63 A and 31.5 A for

1000 kVA & 500 kVA respectively.

MZEC has already started to implement two smaller ratings, namely 25 and 50 kVA to minimize

transformer losses arising from using higher ratings for loads which are far away less than the

capacity of the transformer.

The number of distribution substation exist in the system up to the September 2017 is shown in

Table 4.

Table 4: Number of distribution transformer until September 2017

Governorate Number of Distribution Substation

North Al Sharqiyah 4038

South Al Sharqiyah 2557

Al Dakhilyiah 5175

South Al Batinah 5982

Total 17752

3.3.2 Overhead lines

Overhead lines are extensively used. These are mainly bare ACSR conductors with conductor sizes

of 100 mm2 (dog) or 150 mm2 (wolf) on wooden poles supported by post insulators. MZEC also

introduced SAX insulated conductor in areas suffering from severe climates such as Jalan Bani Bu

Ali and Sur. There is a total of 9495.7 km of 11 kV overhead lines until September 2017 represents

the second highest length of installed circuits in the systems.



20

18

-

2

02

0


The 11 kV underground cables are mainly used to connect overhead lines with primary substations,

connect some distribution substations with overhead lines, road crossings situations and in urban

areas and towns where overhead lines cannot be installed. The standard sizes commonly in use are

50 mm2, 70 mm2, 120 mm2, 185 mm2and 240 mm2copper XLPE three-core cables. Both conform to

relevant IEC specifications. However, in the planned areas the connections will only be using

underground cables to comply with the Policy of Undergrounding. As stated earlier the increase of

use of underground cable have pushed the total installed 11kV underground cables upward and

reached around 2930.6 km in September 2017 and expected to increase dramatically in the following

years.

3.3.4 Short Circuit Levels

Switchgear installed on the 11 kV Distribution System will be specified with a three-phase

symmetrical short circuit rating not less than 18.4 kA at 11kV.

3.3.5 Protection

All feeders are protected against over-current and earth faults whether emanating from indoor or

outdoor primary substations and distribution transformers are protected with expulsion fuses on the

high voltage side and HRC fuses on the low tension side. In general, the protection will be time

graded and arranged to limit the disruption of supplies in the event of a system fault.

4. The Low Voltage System


The main purpose of the LV distribution system is to distribute electricity in local urban or rural areas

and to deliver it to customers' LV entry points in an economic, efficient, safe and secure manner.

The LV system will normally be developed as a network of tapered radial mains supplied from a

distribution substation placed near to the load Centre.

4.2 System Security

MZEC’s low tension network is designed and will be developed to meet its customer’s satisfaction

and comply with the approved Distribution System Security Standards.

4.3 Selection and Application of plant

4.3.1 Distribution Substations

The main constituents of the distribution substations are the 11/0.433 kV transformers and feeder

pillars or cutout boxes. The 800A and 1600 A feeder pillars are normally used with Ground Mounted

transformers whereas 400 A control boxes are used for Pole Mounted transformers.



20

18

-

2

02

0

4.3.2 Overhead Lines

Low tension feeders radiate from the distribution substations as insulated overhead lines to supply

the customers by Tees either with overhead lines on 9 meter wooden poles or underground cables.

New main lines are constructed using insulated conductors of cross-sectional area 120 mm2, 185

mm2 and 200 mm2 according to the load although 95 mm2 are still in use. There are around 9920.2

km of installed overhead lines till September 2017 and the increase of this type is expected to slow

down looking to the intensive use of the underground cable.


Underground cables are used to connect the overhead lines to the distribution substations. They are

also used to connect the premises to the overhead lines. These are of varying sizes such as 1x630

mm2, 4-core 120 mm2, 4-core 150 mm2, 4-core 185 mm2 and 4-core 240 mm2. In new planned areas,

the LT network will be of underground cables only to comply with the Undergrounding Policy. A total

length of 7682.1km of underground cable up to September 2017 is very likely to increase with steep

trend more than the previous years.

4.3.4 Protection

Low tension feeders are protected with HRC fuses at the feeder pillars or cutout boxes.

5. Operating Voltage

The following Table 5 shows MZEC’s operating voltages.

Table 5: MZEC’s operating voltages

Normal System voltage Highest

voltage

Target voltage Allowable

tolerance

415/240 V - 415/240 V ± 𝟔%

11 kV 12.5 kV 11.5 kV ± 𝟔%

33 kV 36 kV 33 kV ± 𝟔%

6. Load Management Areas

During the normal operation of the distribution system, there are no areas of MZEC distribution

network affected by load management scheme. Load management schemes will be employed for

the Demand Control. The need for reduction in Demand arises in situations of insufficient Generation

Capacity and where severe operating difficulties pose a threat to the stability of the Main

Interconnected System including the security of the Distribution System.

7. Other Interconnected Networks

The main interconnection with other networks is with OETC system via grid supply point substations.

These are eight grid substations in South Al Batinah namely Barka Main, Al Sawadi, Muladah, MIS,



20

18

-

2

02

0

Rustaq, Nakhal, Khdrah and Madinat Barka TX-1 & Tx-2, and eight grid substations in Al Dakhilyiah

namely Nizwa, Madinat Nizwa, Bahla, Izki, Izki-2, Sumail-A, Sumail-B and Adam, three grid

substations in South Al Sharqiyah namely Sur, Jalan BB Ali and Jalan BB Hassan, and three grid

substations in North Al Sharqiyah namely Mudhairib, Ibra and Mudhaibi. Interconnections on the 33

kV and 11 kV voltage level are with Majan Electricity Company and Muscat Electricity Distribution

Company. The 33 kV interconnections with Majan Electricity Company and Muscat Electricity

Distribution Company are mainly alternative supply sources in emergency situations. At some

locations, MZEC has Interconnection with the Ministry of Defence (MOD) which serves mainly for

the import and export of energy which depends on the condition of the demand.

8. The 33 kV System Load Flow Study

8.1 Introduction

A load flow study is necessary to verify that the electrical system has the adequate capacity to supply

the connected load.

In distribution systems, load flow studies are performed to determine the steady-state operation of

the distribution system. A load-flow study calculates the voltage drop on each feeder, the voltage at

each bus, and the power flow in all branch and feeder circuits. Losses in each branch and total

system power losses are also calculated.

Normally, load flow studies determine if system voltages remain within specified limits under various

operating conditions, and whether equipment such as transformers and conductors are overloaded.

Load flow studies are often used to identify the need for additional generation, capacitive, or inductive

VAR support, or the placement of capacitors and/or reactors to maintain system voltages within

specified limits.

Commonly, load flow studies are carried out to investigate:

1) Bus Voltage Profiles

2) Real and Reactive Power Flow

3) Power System Losses

4) Proper Transformer Tap Settings

A load flow study was conducted on MZEC’s 33 kV distribution system.

8.2 Purpose of the Study

This load flow analysis is carried out in accordance with the requirements of Condition 32:

Distribution System Capability Statement of our Distribution and Supply License and the Distribution

Planning Code DPC.4.4 (Three Year Capability Statement). It is intended to study and analyze

MZEC’s 33 kV distribution system from the planning and operation points of view.

8.3 The 33 kV Distribution Network

MZEC’s 33 kV distribution network is composed of four isolated networks:

1) Al Dakhilyiah Distribution Network

2) North Al Sharqiyah Distribution Network

3) South Al Sharqiyah Distribution Network

4) South Al Batinah Distribution Network



20

18

-

2

02

0

Each of them is fed from the 132/33 kV or 220/33 kV Grid Stations, where 33 kV outgoing feeders

are radiated to feed the 33/11 kV primary indoor and outdoor substations in addition to few pole

mounted 33/0.433 kV transformers.

8.4 The Load Flow Analysis

The starting point of the load flow analysis is the existing 33 kV networks of the four governorates in

summer 2017. Using ETAP software, load flow for the Loading Category Summer 2017 was

conducted, using the measured loads of summer 2017, for the four governorates, Al Dakhilyiah, Al

Sharqiyah (South and North) and South Al Batinah separately. In this study, the measured 11 kV

currents which were measured in the 11 kV feeders of substations were used to carry out this study.

As the purpose of the present load flow analysis is to assist preparing MZEC’s Capability Statement

for the period 2018-2020, the measured loads were used as the basis for the studies in 2018, 2019

and 2020. The results of each study phase (Loading Category) were analyzed in relation to

equipment’s loading and voltage magnitudes at the 33 kV and 11 kV buses. Equipment with

overloading and bus bars with under voltages were identified. The network reinforcement required

to relief the overloaded equipment and improve the voltage profiles are proposed and the networks

of the four governorates are modified accordingly and a new load flow study is conducted.

Complete and Summary reports for each region are available on request.

8.5 Presentation of Results and Single Line Diagrams for the Years 2018-2020

For simplicity and ease of understanding, the results of the load flow analysis are regenerated in MS

Excel spread sheets in the annexure listed below.

1) Annexure 1-A-1: Al Dakhilyiah Equipment Loading (Primary Substations)

2) Annexure 1-A-2: Al Dakhilyiah Equipment Loading (33 kV Feeders)

3) Annexure 1-B-1: South Al Sharqiyah Equipment Loading (Primary Substations)

4) Annexure 1-B-2: South Sharqiyah Equipment Loading (33 kV Feeders)

5) Annexure 1-C-1: South Al Batinah Equipment Loading (Primary Substations)

6) Annexure 1-C-2: South Al Batinah Equipment Loading (33 kV Feeders)

7) Annexure 1-D-1: North Al Sharqiyah Equipment Loading (Primary Substations)

8) Annexure 1-D-2: North Al Sharqiyah Equipment Loading (33 kV Feeders)

The single line diagrams for the years 2018, 2019 and 2020 are available on request.

9. The 33 kV Short Circuit Analysis

It is normally understood by the short-circuit calculation, the calculation of the characteristic short-

circuit quantities. Namely, Initial Symmetrical Current, Peak Current, Breaking Current and the

Steady State Current. These currents can produce considerable thermal and mechanical stresses

in electrical distribution equipment. The faults causing these current interrupt the system’s steady-

state operating condition and may lead to instability, loss of synchronism and outages. Their

calculation is a perquisite in system design, planning and operation to ensure that the system

components are properly selected to withstand these abnormal currents and the protective devices

are capable to detect and interrupt them. Proper interruption of these currents will protect the

personnel, public, animals as well as the equipment.



20

18

-

2

02

0

The Short Circuit Study is conducted on Mazoon’s 33 kV distribution network as part of its Three

Year Capability Statement in accordance with the requirements of Condition 32 of MZEC Distribution

and Supply License. The short circuit study is carried out on the Mazoon’s three 33 kV networks for

the years 2018 - 2020 using ETAP. In the study, only load connected buses are short circuited i.e.

33 and 11 kV busbars excluding nodes.

The results showed that all the short circuit currents are below the equipment rating in all

governorate.

For simplicity, only the 3- Fault Currents for the years 2018, 2019 and 2020 are shown. These are

presented in Annexure 2-A-1, 2 & 3, 2-B-1, 2 & 3, 2-C-1, 2 & 3 and 2-D-1, 2 & 3 for the four

governorates Al Dakhilyiah, South Al Sharqiyah, South Al Batinah and North Al Sharqiyah

respectively.

10. Voltages Non Compliance

Non-compliance towards the voltage standards is presented for the 33 kV busbars at the primary

substations only. The voltage non-compliance observed at the 33 kV busbars is not affecting the

voltage at the 11 kV busbars, due to the existence of the tap changers. Due to the fact that the

majority of MZEC customers are connected at the LV network, there is no clear and reliable

information on the number of voltage non-compliances at the customer premises. However, MZEC

keeps records of customer complaints and take them into consideration while carrying out the

reinforcement programs. The partial incorporation of 11kV modeling into the upcoming Capability

Statements will provide a better picture on the status of voltage at the customer side. Having said all

of the above, it is worth mentioning that at peak hours the voltage at the grid substations falls beyond

the normal operating value. The voltage non-compliances are shown in Annexure VD-A-1, 2 & 3,

VD-B-1, 2 & 3, VD-C-1, 2 & 3 and VD-D-1, 2 & 3 for the four governorates Al Dakhilyiah, South Al

Sharqiyah, South Al Batinah and North Al Sharqiyah governorates respectively for period 2018 -

2020. However, we are maintaining the voltage level at 11 kV through the capacitors and

Transformer tap changer, so that the voltage with distribution user are maintained within ±6%.The

proposed reinforcement projects will relief the distribution system components and consequently,

the voltages at the non-compliant buses will be improved.

The additional capacitive capacity will bring the power factor at the primary level within the range of

(0.95 lagging to 0.95 leading) specified in the Distribution Code and Grid Code and help keeping the

voltage within ± 6% . Furthermore, the reduction of the reactive current flowing in the 33 kV network

for long distance will reduce the distribution losses.

11. Distribution System Security Standards (DSSS)

After the approval of Distribution System Security Standards in November 2008 as shown in Table

6 below, MZEC is obliged to comply with the Planning requirements of Security Standards. Since

the grant of MZEC’s Distribution and Supply License, MZEC has started planning its distribution

network to comply with simple planning principle to supply its customers with a high quality product.

The starting point was the purchase of high quality power system analysis software, namely

Electrical Transient Analysis Program (ETAP), for the analysis of its distribution system. The 33 kV

networks of the four governorates namely Al Dakhiliyah, Al Sharqiyah (South and North) and South

Al Batinah were drawn in the ETAP as early as 2006 and MZEC presented its first Three Year

Capability Statement with the aid of this powerful software. The results obtained from the ETAP



20

18

-

2

02

0

encouraged MZEC to purchase another three Licensees for its 11 kV networks and also upgraded

the original version.

Table 6: Distribution System Security Standards

DEMAND CLASS Initial System Conditions

First Outage

(Forced Outage)

Second Outage

(Planned Outage + Forced

Outage)

A Less than 2 MW Repair time No requirement

B 2 to 6 MW 3 Hours No requirement

C 6 to 20 MW Within 15 minutes Restoration time of planned outage

D 20 to 100 MW Immediately Restoration time of planned outage

E Greater than 100 MW Immediately Immediately, 2/3rds of demand

The load flow study carried out on the 33 kV networks of the four governorate showed compliances

and non-compliances towards Distribution System Security Standards for the 33 kV feeders and the

33/11 kV substations. The study is based on the measured currents of the 33/11 kV substations in

summer 2017 for the load category 2017. The results of the study for the three years 2018-2020

were analyzed against the security standards for the feeders and the substations for each

governorate separately. The 33 kV feeders and 33/11 kV substations that are not complying with the

Distribution System Security Standards (DSSS) are presented in a tabulated form of prospective

security derogation lists.

According to the Security Class, a 33 kV feeder is considered not complying with the standards if,

upon a fault on the feeder the Demand Group cannot be supplied within the prescribed period of

time. Where a portion of the feeder cannot be fed back, the feeder is considered and classified as

non-compliant. For the 33/11 kV substations, two situations are of interest. In the first case, if two

transformers are installed in a substation but the total load is greater than the capacity of one

transformer, then the substation is considered non-compliant. The second situation is where only

one transformer is installed and there is no link to a nearby substation that can take the affected

demand group, then the substation is considered non-compliant. It is worth mentioning that the non-

compliance is only during the summer period. For most of the year many feeders and substations

are compliant with the DSSS except the radial feeders, T-Offs and substations with only one installed

transformer. All investments in MZEC Network are to make all substations compliance with DSSS.

12. Demand Forecast



20

18

-

2

02

0

12.1 Introduction

MZEC’s annual peak demand forecast is the essential first value of input into development plans.

Annual peak demand is the highest rate of energy demand across the course of a year. By monitoring

and planning for peak demand, MZEC ensures the distribution networks maintain the ability to

provide a reliable supply under the most strenuous load demand conditions. MZEC is monitoring

and reviewing the peak demand annually to ensure:

Identify the change of load trends.

Looking for the impact of increasing load to the customer especially Industrial and

commercial.

Development of the efficient network expansion plans to match the demand forecast and

support economic development.

Observation of annual peak load ensures the most recent information and country development are

considered when forecasting the expected impact on each individual substations and the total

system peak for the main interconnected system. For each substation, separate measure are used

to determine the substation peak load and the substation load at the time of the total system peak

load as each of these peak loads may not occur at the same time or have the same drive. Moreover,

the detailed geographical level of substation allow distribution planning to identify demand growth in

the area.

MZEC is one of the areas rapidly developing in Oman. Because the government provides the basic

infrastructure in this areas, so the people are encouraged to invest and build in MZEC areas

especially in South Al Batinah Governorate which is the most densely populated governorate in the

Sultanate. Next table shows the percent growth from 2008 until 2017. It’s obviously the percent of

growth increased rapidly in 2011 and 2012 and the sharp drop in load growth in 2010 was due to

adverse weather conditions.



20

18

-

2

02

0

Figure 1: MZEC peak load

The average growth as be seen in above figure is approximately 7.2% for all MZEC area. It’s

expected to increase the load for upcoming years. Because MZEC recognized non ordinary growth

driven by considerable number of governmental investments in form of tourism projects,

infrastructure projects, and industrial projects as well as private sector investments accompanying

them.

12.2 Load Curves

To give a general view of the load behavior, the load profiles for MZEC taken at Sunday 25th June

2017 which is the day of MZEC Peak was plotted and presented in Figure 2 below. The highest load

was reached at 15:00 hours due to in this hour most of the people returned to their houses to take

rest after duty time, in this day the load recorded was 2120 MW.

Figure 2: The Load Profile of MZEC

0

9.7

2.4

11.311.1

5.2

8.2

12.5

4.9

6.8

0

2

4

6

8

10

12

14

0

500

1000

1500

2000

2500

2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

MZEC Peak Load MW & %Growth

Peak load MW % Growth

0

400

800

1200

1600

2000

2400

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

MW

Hours

Daily Load Carve



20

18

-

2

02

0

Similarly, a weekly load profile covering the period from 22th June to 28th June 2017 was plotted in

Figure 3 to show the load behavior of MZEC load in a typical week of the year. The selected week

included MZEC peak day. It is obvious that the load during weekend slightly less than that during

normal days.

Figure 3: Weekly Load Profile

To complete the picture, the yearly load profile for year 2017 until October was also plotted in

Figure 4. The yearly load profile was obtained from plotting the highest reading in each month to

from the Maximum load profile for the entire MZEC System as well as for each governorate.

Figure 4: MZEC Yearly Load Profile 2016 (Jan-Oct)

0200400600800

10001200140016001800200022002400

Thursday Friday Saturday Sunday Monday Tuesday Wednesday

MW

Weekly Load Profile (22 June - 28 June 2017)

Max Load MW Min Load MW

0

500

1000

1500

2000

2500

MW

Months

MZEC Max Load MW Dakhiliyah Max Load MW

North Sharqiyah Max Load MW South Batinah Max Load MW

South Sharqiyah Max Load MW



20

18

-

2

02

0

Mazoon Load curve follows a typical load behavior in hot countries as the peak period is in summer

season that starts approximately in April and ends in September. It can be also of importance to

notice that MZEC Peak is almost three times its minimum load recorded in off peak period during

January and February. The demand side management need to consider this issue to minimize the

gap between peak period and off peak period which no doubt will result on savings at generation,

transmission and distribution systems.

As can be seen from the graph of Figure 4, that South Al Batinah Load represent the highest load

among the all the governorates followed by Al Dakhilyiah and Al Sharqiyah (South + North)

governorate.

12.3 Demand forecast Methodology

This section covers the forecast methodology and the results of MZEC’s forecast of energy demand

expressed in Regulated Units Distributed (RUD) and customer accounts (CA) for 2018 – 2022. The

demand forecast is a fundamental driver of the subsequent forecasting of Price Control 5 (PCR5).

Crucially the forecast makes a distinction between autonomous demand growth and that due to

corporate projects.

Autonomous demand growth: driven by the year-on-year increase in the number of customer

accounts and in the regulated units distributed which are derived from the increase in the population

within the MZEC service area and GDP per capita. Even with uncertainty and statistical errors that

occur in the source data, it is reasonable to suppose that both drivers will grow at a fairly predictable

rate that reflects the immediate past history of its actual growth.

Corporate projects: Customer accounts and especially distributed energy will also increase as a

consequence of significant, large-scale developments referred to as corporate projects. The timing

and impact of the corporate projects on MZEC’s network is difficult to predict as such projects

constitute a variety of national initiatives influenced by national and international factors, developers’

priorities and timescales, and other factors outside of MZEC’s control and reasonable forecasting

practices. Corporate projects at completion typically add a one-off increase in the number of

customer accounts (large or small, according to their nature) and in the units distributed (which may

then have its own annual growth rate as the development matures). MZEC bases its forecast of the

impact of corporate projects on a mix of historical trends, current developments, and communication

with developers and the government.

Autonomous Demand Growth

The forecast of autonomous demand growth is based on an econometric model developed for the

Price Control 5 (PCR5) submission, using the latest available data on population growth and

economic (GDP per capita) growth in Oman. Both factors are key drivers for the increase in customer

accounts as well as the average energy consumed per customer account. International studies show

a significant positive correlation between GDP per capita and average energy consumption per

capita. As the GDP per capita of a country rises, private households are able to afford more electrical

appliances, and industrial and commercial enterprises replace labor with capital. The link between

population growth and the number of customer accounts is self-evident. MZEC’s confidence in the

robustness of this econometric model has been reinforced by the good agreement between its



20

18

-

2

02

0

forecasts made for PCR5 and the actual outturn in number of customer accounts and units

distributed in 2011 to 2015.

The input data used in the forecast is as follows:

1. Population data for the area served by MZEC has been taken from data published by the

Oman Information and Statistics Center1; and

2. Data and projections on Oman GDP economic development are taken from data published

by the International Monetary Fund in its World Economic Outlook Database2.

Corporate Projects/Customers

MZEC classifies as Corporate Projects those developments known to MZEC as of December 2016,

where the developers or prospective customers have indicated their intention to connect substantial

new loads to the MZEC network. These have an effect on the load expected to be distributed in the

period of the PCR5 price control, of a magnitude and incidence that is difficult to anticipate,

dependent as it is upon the independent decisions of developers and major customers which are in

turn subject to a variety of factors.

The additional number of customer accounts involved in these projects can be quite small, but the

increase in energy consumed can be very substantial with a significant impact on the total energy

distributed to these categories, e.g. the Industrial, Tourism, and Ministry of Defense (MoD) sectors.

For these three categories, MZEC may reasonably assume – absent any indications to the contrary

– that existing demand (as of end-2016) will not exhibit significant autonomous growth (existing

tourist facilities will maintain their occupancy level – and hence energy consumption, as will MoD

facilities; existing industrial plants will operate at the current level of production). The volume and

timing of demand growth in the Tourism and Industry categories depends on national and

international economic developments as well as decisions by individual investors. MoD expansion

of new facilities is mostly driven by political decisions internal to Oman. MZEC is therefore only able

to forecast demand growth due to those industrial, tourism or MoD projects known to MZEC as of

December 2014, that are expected to be connected during the PCR5 price control period. Other

corporate projects known to MZEC are in the Residential (such as the South Al Batinah Coastal Area

Residences), Commercial and Government categories. Whilst not negligible, these projects will add

a relatively small increase to the number of customer accounts and units distributed in these already

very large customer categories.

The number of all such projects, their incidence and nominated peak demand expected in the

Capability Statement 2017-2019 period are:

1http://www.ncsi.gov.om/NCSI_website/viewPublication.aspx?id=1958, published Jan 2014

2https://www.imf.org/external/datamapper/index.php, published Jan 2014



20

18

-

2

02

0

Table 7: Peak Demand in MW of Corporate Projects by Customer Category expected in 2018-2020

Customer category

Number of projects

Peak Demand (MW)

2018 2019 2020

Residential 0 0 0 0

Government 19 61 66 82

Commercial 7 18.8 21 31

Industrial 4 60 65 89

Agriculture 1 3.2 3.2 3.2

Tourism 1 17.6 17.6 17.6

MOD (Defense) 3 15.8 22.6 22.6

Our forecast of the number of customer accounts and the units distributed under these corporate

projects is based on the prospective connection data made available to MZEC by the project

developers. Using their project timetable and their nominated MW capacity or peak demand, the

MZEC Planning Department:

1. Reviews and analyses, discuss and validate the requests with the developers to arrive at

reasonable values of total connected load; and

2. Estimates their coincident after diversity and load factor (CADLF) energy consumption using

diversity and load factors determined from comparable historic data in the MZEC area and

from corresponding data in comparable countries.

Whilst MZEC recognizes the inherent uncertainty introduced to the demand forecast by basing

special project figures on the developers’ own proposed timetable and capacity requirements, MZEC

is reasonably confident that adding these estimates to the values produced by our econometric

model introduces a negligible error to the forecast of customer accounts and energy distributed in

the PCR5 price control period.

Table 8: MZEC coincident after diversity and load factor Tariff category

Residential Government Commercial Industrial Agriculture

Coincident Factor 60% 40% 60% 80% 30%



20

18

-

2

02

0

13. Future System Development Projects

From the load flow study carried out on Mazoon’s 33 kV network, loaded and overloaded equipment

together with bus bars suffering under voltage conditions are identified. Necessary measures

required to relief the equipment and improve the voltage, are presented in a form of three strategic

development statements explaining the changes will be experienced by each Governorate.

Annexure (1-A-1, 1-A-2, 1-B-1, 1-B-2, 1-C-1 and 1-C-2) that illustrate the loading and the status of

compliance with the DSSS and presents the effect of these measures up to the end of this capability

statement which is year 2020. The fifth Price Control 2018-2021 aims to improve the situation of the

compliance with DSSS in primary substations and 33 kV feeders gradually. In addition, MZEC has

prepared a plan for the new investments required in 2018 to reinforce the 33 kV network and to

ensure the compliance with the security standards. Many of substations and feeders will start moving

towards the compliance situation. However, there are many other substations and feeders need

more investments to be complied. As MZEC is experiencing a round two digit growth annually, it is

challenging to plan and deliver all the required investments to cater for the load growth and comply

as much as possible with the Security standards requirement taking into consideration the

increasingly developing internal and external capabilities. MZEC has taken various steps to tackle

any bottlenecks in the project management cycle and with these interventions our capabilities to

deliver all the required capital expenditure will no doubt improve.



20

18

-

2

02

0

Table 9: 33 KV Projects for Al Dakhilyiah 2018-2020

No. PIAD No. Project Name District Expected

completion Year Project Status Target

1 DH 04/2013Upgrading of Kamah Substation to 2x20 MVA with one

new 33 kV feedersNizwa 2018 Commissioning Stage

To enhance the compliance to

the security standards

2 DH 1/2012Upgrading of Hay Al Ain to 3x6 MVA with two new 33

kV feedersNizwa 2018 Commissioning Stage



3 DH 08/2013 Construction of new 2x20 MVA Al Mamorah substation Bahla 2018 Commissioning StageTo relive load from Bahla Grid

Substation

4 DH 09/2012 Construction of New Jibreen Grid Bahla 2018 Commissioning Stage To relive load from Bahla Grid

5 DH 07/2013 Al Zoubar 2x20 MVA with 2 new 33 kV feeders Adam 2018 Commissioning StageTo relive load from Adam Grid

Substation

6 DH 08/2013 Upgrading Timsa substation to 2x20 MVA Nizwa 2018 Commissioning StageTo enhance the compliance to


7 DH 01/2012 New 33 kV feeder from Madinat Nizwa to Hay Al Ain Nizwa 2018 Commissioning Stage To supply Hay Al Ain Tx-3

8

Due to

Complex

Connection

Upgrading Mitan to 2x6 MVA Adam 2018 Commissioning StageTo enhance the compliance to


9 DH 05/2013Construction of New Qalat Al wamer (Izki-2) Grid with

3 new 33kV feedersIzki 2018 Commissioning Stage To relive load from Izki Grid

10 DH 02/2013New 2x20 MVA substation is proposed to be

constructed in Jebel Al Akhder areaIzki 2018 Commissioning Stage

To meet high growth in the area

and relive some load from Jebel

Al Akhder 2x6 MVA .

11 DH 05/2013 Upgrading Al Aqil substation from 1x6 MVA to 2x6 MVA Izki 2018 Commissioning StageTo enhance the compliance to


12 DH 05/2013

Upgrading Somrah substation from 2x6 MVA to 3x6

MVA and Wadi Mahram substation from 1x6 MVA to

2x6 MVA

Izki 2018 Commissioning StageTo enhance the compliance to


13 DH 06/2012Construction of Sumail Industrial Zone-1 3x20 MVA

substation with two new 33 kV feedersSumail 2018 Commissioning Stage To meet high growth in the area.

14 DH 06/2012Construction of Sumail Industrial Zone-2 2x20 MVA

substation with two new 33 kV branchesSumail 2018 Commissioning Stage To meet high growth in the area.

15 DH 05/2012 Upgrade AL Hamim to 3x6 MVA Sumail 2018 Commissioning StageTo enhance the compliance to


18 DH 05/2012Construction of Saih Al-Moaideen 2x20 MVA

substation with two new 33 kV branches Sumail 2018 Commissioning Stage


and relive some load from

BidBid Substation and Multqa

Substation .

20 DH 02/2013

Constrcution of 33kV Double Circuit Towers Lines

From Izki Grid to New Jabal AL Akhdher Primary

Substation

Nizwa 2019 Designing StageTo supply New Jabal AL

Akhdher 2x20 MVA

21 DH 05/2013Upgrading Qalat AL Awamer substation from 2x6 MVA

to 2x20 MVA with 2 new 33 kV feeder from Izki-2 Grid.Izki 2019 Execution stage



22 DH 05/2013

Construction of Al-Hamim 33 kV feeder from Sumail

Grid to Bidbid 2x6 MVA, Fanja Water Pump and MOD

Bidbid

Sumail 2019 Designing StageTo relive load from Fanja-1 and

Fanja-2 33 kV feeders

23 DH 05/2013Extend existing Al Aqil 33 kV feeder into Humaidha

S/S with auto changeover. Izki 2019 Designing Stage To supply Humaidha Tx-3

24 DH 05/2013Upgrading Humaida substation from 2x6 MVA to 3x6

MVAIzki 2019 Execution stage To meet high growth in the area.

25 DH 05/2013

Construction of 2x6MVA PSS (Al Sayma)with 33KV

feeder from existing Feeders and 11KV feeders at Izki

in Al Dakhiliyah Governorate

Izki 2019 Designing Stage


and relieve load from Sayma

Temp. Substation.

26 DH 09/2012Construction of a new 3x20 MVA substation in Al

Hamra.Bahla 2019 Execution stage


and relive load from Al Hamra

Substation.

27 DH 07/2013 Upgrade Adam Grid from 2x63 MVA to 2x125 MVA Adam 2019 Designing StageTo enhance the compliance to


28 DH 08/2013Construction new Grid in Birat Al Mouz with capacity

of 2x125Nizwa 2020 Designing Stage To relive load from Izki Grid

29 DH 08/2013Construction of new 2x20 MVA Hay Al Turath

substationNizwa 2020 Designing Stage


and relive some load from

Nizwa Stadium Substation and

Farq Substation .

30 DH 08/2013Upgrading Izz substation from 1x6 MVA to 2x10 MVA

indoor substationNizwa 2020 Designing Stage



31 DH 09/2012Upgrading Al Habi substation from 2x10 MVA to 2x20

MVABahla 2020 Designing Stage



32 DH 07/2013Construction new Jibreen 2x20 MVA primary

substationBahla 2020 Designing Stage


and relieve load from Jibreen

Substation.

33 DH 05/2013Construction new 2x20 MVA substation called Al

Afiyah with one new 33 kV feeder from Izki GridIzki 2020 Designing Stage


and relieve load from Al Afiyah

Temp. Substation.

34 DH 06/2012 Construct Sumail Industrial grid with 33 kV switchgear Sumail 2020 Designing StageTo relive load from New Sumail

Grid



20

18

-

2

02

0

Table 10: 33 KV Projects for South Al Sharqyiah 2018-2020


Completion Year Project Status Target

1

SH-02/2012

Upgrading Al Kamil primary substation from 2x20

MVA to 3x20 MVA with constructing 33 kV branch

between Al Kamil primary substation and Al Kamil

Water Pump

Jalan BB Hassan 2018 Commissioning Stage

To comply with DSSS and

relieving the load from existing

primary substation

2

SH 01/2012Construction of a new 3 x 20 MVA primary substation

Jalan Bani Bu Hassan-2Jalan BB Hassan 2018 Execution stage

Relieve the load from existing

JBB Hassan primary substation

3 SSH 03/2016 Upgrade Al Ashkharah primary substation to 2x20

MVAJalan BB Ali 2018 Designing Stage



primary substation

4 CC/08/2016New 33 kV feeder from Sur Grid to Al Jinah 2x10 MVA

SubstationSur 2019 Commissioning Stage

To secure the 33kV supply to

ROP Headquarter, Sur ROP

and Al Jenah primary

substations

5 SH 01/2012Upgrading Stadium substation from 2x6 MVA to 2x20

MVA with new 33kV branchSur 2020 Designing Stage



primary substation

6 SH 01/2012

Construction of a new Al Egga Grid 2 x 20 MVA

primary substation with two dedicated feeders from

Al-Egga Grid

Sur 2020 Designing Stage


Sur Town and Al Shariyah

primary substations

7 SH 01/2013Construction of Al Musfiyah 3 x 20 MVA primary

substation with three dedicated feeders from Sur GridSur 2020 Designing Stage

Relieve the load from existing Al

Egga and Shiya primary

substations



20

18

-

2

02

0

Table 11: 33 KV Projects for South Al Batinah 2018-2020



1 SB-35/2012 Construction of 33 kV switchgear of Khadra -B Grid Suwaiq 2018 Execution stage To releif load from MIS Grid

2

SB-01/2012 Upgrading Bidaya from 2x20 MVA to 3x20 MVA Suwaiq 2018 Execution stage


and relieve some load from

Bidaya suq 2x6 MVA and Shabyah

2x6 MVA.

3

SB-04/2013

Construction of AL Batha 3x20 MVA substation with

three feeders link with existing (Khadhra-1, Khadhra-2 &

Marbal Factory) feeders MIS grid.

Suwaiq 2018 Commissioning Stage

To relieve loads from Suwaiq, AL

Hatheeb and Suwaiq I Area

Substations

4SB-22/2012

Upgrade Wadi AL Jahawer to 2x6 MVA and Al Haimly to

2X6 MVASuwaiq 2018 Execution stage

To enhance the compliance to the

security standards

5

SB-01/2012Construction of Badi Al Amod 3x20 MVA substation with

new two feeders.Suwaiq 2018 Execution stage

To be ensure compliance of

security standards of Bidaya

substation

6SB-01/2012

Upgrading od Dhyan 2x20 MVA substation with new two

feedersSuwaiq 2018 Execution stage


security standards

7

SB-02/2013Construction Al Uraiq 3x20 MVA substation with three 33

kV feeders from Khadra gridSuwaiq 2018 Execution stage

To relieve loads from Khahra,

Khadra Bu Rshaid and Al Uqdah

Temp

8SB-35/2012

Construction two new feeder to Marble Factory 3x6 MVA

substationSuwaiq 2018 Execution stage To relieve load from MIS Grid

9SB-35/2012

Construction of two new feeders to Khadhra Bu Reshaid

2x20 MVA substation Suwaiq 2018 Execution stage To relieve load from MIS Grid

10 SB-35/2012 Construction of new 33 kV feeder to Bidaya Tx-3. Suwaiq 2018 Execution stage To supply Bidaya Tx-3

11SB-04/2013

Construction of Suwaiq Grid 33 kV busbar and 33 kV

switchgear with nine 33kV feedersSuwaiq 2018 Execution stage To relieve load from MIS Grid

12Coastal Area PIAD

Construction of Musanah Al Sahil 3x20 MVA substation

with three feeders from Blue City GridMusnah 2018 Commissioning Stage

To relieve load from Musansh

Substation

13SB-05/2013 Upgrading Maharh from 2x20 MVA to 3x20 MVA. Musnah 2018 Execution stage


security standards

14SB-05/2013 Upgrading Muladah from 2x20 MVA to 3x20 MVA Musnah 2018 Execution stage


security standards

15SB-05/2013

Construction of Muladah-B Grid 33 kV busbar and 33 kV

switchgear with five 33kV feedersMusnah 2018 Commissioning Stage

To relieve load from Mulladah

Grid

16SB-05/2013 Constructing Maghser South 2x6 MVA Substation Musnah 2018 Execution stage

To relieve loads from Maghser

South Temp. Substation

17SB-05/2013

Upgrading Musanah Industrial from 1x3 MVA to 2x20

MVA Substation Musnah 2018 Execution stage


security standards

18SB-08/2013

Upgrading of Wadi Bani Awf substation from 1x6 MVA to

2x20 MVARustaq 2018 Execution stage


security standards

19SB-07/2013 Construction of 33 kV switchgear of Madinat Barka-B Grid Barka 2018 Execution stage

To relive load from Madindt Barka

-A Grid.

20SB-07/2013

Upgrading of Barka Town substation from (2x 20 MVA) to

(3 x 20 MVA) with a 33kV feeder from Madinat Barka GridBarka 2018 Commissioning Stage


security standards

21SB-07/2013

Construct of Saqsuq-1, Saqsuq-2 and Saqsuq-3 to relive

load from Madinat Barka-BBarka 2018 Execution stage

To relieve load from Madinat

Barka _A Grid.

22 CC/04/2015 Construction of 33 kV switchgear of Hai Asem Grid Barka 2018 Commissioning Stage

23

SB-07/2013

Constructing of Al Huradi substation with a capacity of

3x20 MVA and three new 33 kV feeders from Madinat

Barka Grid-B

Barka 2019 Designing StageTo relieve load from Somahan

and Barka New substations

24

SB-07/2013

Constructing of Somahan South substation with a

capacity of 2x20 MVA and two new 33 kV feeders from

Madinat Barka Grid-B

Barka 2019 Designing Stage

To relieve load from Barka Town

substation, Somahan and

Somahan South Temp

25SB-07/2013

Constructing Al Haram 3x20MVA substation with three

33kV feeders from Hai Asem Grid.Barka 2019 Designing Stage

To relieve load from Rumais and

Salaha substations

26SB-07/2013

Upgrading of Al Uqair substation to 2x20 MVA with a new

33kV feeder tapping from Barka-5 feeder. Barka 2019 Designing Stage

To be complying with DSSS

requirements

27SB-09/2013

Construct a new Wadi Al Sahtan 1x6 MVA substation in 4

km away from Wadi Al Sahtan 2x6 substationRustaq 2019 Designing Stage

To relive the substation and to

improve the voltage in this area

28

SB-09/2013Upgrading of Wadi Bani Ghafer from 2x6 MVA to 2x20

MVA with 2 new 33 kV feeders from Wadi Bani Awf GridRustaq 2019 Execution stage


security standards

29SB-09/2013

Upgrading of Al Hazim substation from (2x 6 MVA) to (2 x

20 MVA) Indoor substation. Rustaq 2019 Execution stage


requirements

30SB-09/2013

Upgrading of Awabi substation from 3x6 MVA to 2x20

MVARustaq 2019 Execution stage

To comply with DSSS

requirements

31SB-09/2013 Construction of new 2x6 MVA substation in Al Marji area Rustaq 2019 Designing Stage To relive Al Kahaf substation

32

SB-09/2013Constructing of Kasfah 2x20 MVA substation with two

33kV feedersRustaq 2019 Execution stage

To relive load of existing Woshil

2x20 MVA, Rustaq 2x20 MVA and

Makhsoufah 2x6MVA substation

33SB-08/2013

Construction of New feeder from Rustaq Grid to Wadi

Bani AwfRustaq 2019 Designing Stage To secure the 33kV supply

34New Upgriding Twayah from 1x6 MVA to 2x6 MVA Substation Nakhal 2019 Designing Stage


requirements

35SB-08/2013 Construction of Al Hajir 1x6 MVA Substation Rustaq 2019 Designing Stage

To relieve loads from Al Haimly

Substation

36SB-09/2013

Constructing of New Woshil 2x20 MVA substation with

two 33kV feeders from Rustaq Grid Rustaq 2020 Designing Stage

To relive load of existing Woshil

2x20 MVA substation

37

SB-07/2013Constructing Hai Asem 3x20MVA substation with three

33kV feeders from Hai Asem GridBarka 2020 Designing Stage

To relieve load from Salaha

substation and Al Haram Temp

substation

38

SB-07/2013 Construction of Felaij 2x20 MVA Substation Barka 2020 Designing Stage

To relieve Load from Felaij

Village, Felaij Temp and Halban

substation



20

18

-

2

02

0

Table 12: 33 KV Projects for North Al Sharqyiah 2018-2020


Completion Year Project Status Target

1

SH 05/2012Construction of new Sinaw-B 2 x 20 MVA primary

substationMudhaibi 2018 Commissioning Stage


Sinaw primary substation

2

SH 02/2013Sinaw 132/33 kV grid station 2x125 MVA with 33 kV

outgoing feeders Mudhaibi 2018 Execution stage


Mudhaibi grid station

3 SH 03/2013

Construction of new Yahmadi substation 2x20 MVA

and construction of two new 33 kV feeders from Ibra

Grid

Ibra 2018 Execution stageRelieve the load from existing

Yahmadi primary station

4 SH 03/2013Construction tow 33 kV feeders from Ibra Grid 2x125

MVA link with existing 33 kV Dima & Tayeen feeders.Wadi Tayeen 2018 Execution stage

To solve the voltage issue at

Wadi Tayeen area

5 SH 04/2013Upgrading Ghayadah substation from 2 x 6 MVA to 3

x 6 MVAWadi Tayeen 2018 Commissioning Stage



primary substation

6 SH 06/2013

Upgrading Wadi B Khalid substation from 2 x 6 MVA

to 3 x 6 MVA, Lawrange substation from 1 x 6 MVA to

2 x 6 MVA and Hiyal substation from 1 x 6 MVA to 2 x

6 MVA

Bidayah 2018 Commissioning Stage



primary substations

7 SH 06/2013Construction of New Shariq Primary 2x 20 MVA

substationBidayah 2018 Execution stage


Mintrib and Al Wasil primary

substations

8 SH 02/2013Construction of new Samad 2 x 20 MVA primary

substationMudhaibi 2019 Execution stage


Samad primary substation

9 SH 02/2013Construction of new Al Khadhra 2x20 MVA primary

substationMudhaibi 2019 Execution stage

Relieve the load from existing Al

Khadhra primary substation

10 SH 05/2012Construction of Samad 132/33 kV grid station 2x125

MVA with 33 kV outgoing feedersMudhaibi 2019 Execution stage


Mudhaibi grid station

11 SH 05/2012Construction of new Saih Al Nama substation 2x20

MVA.Mudhaibi 2020 Designing Stage


Mudhaibi primary station

12 SH 05/2013Construction of the proposed Bidayah 132/33 kV grid

station 2x125 MVA in with related 33 kV feedersBidayah 2020 Designing Stage


Mudhairib grid station

13 NSH 01/2017Construction of Ibra Flaje Primary 2x 20 MVA

substationIbra 2020 Designing Stage


Massroon primary station

14 SH 05/2012Construction of new Sinaw-C 3 x 20 MVA primary

substationMudhaibi 2020 Designing Stage


Sinaw and Sinaw-B primary

substations



20

18

-

2

02

0

Table 13: Sponsor Project in Al Dakhilyiah

Table 14: Sponsor Project in South Al Sharqyiah

No. Reference No. Project Name District Expected


1 CC/01/2015Upgrading ROP Acadmy substation from 1x6 MVA to 3x6

MVA with new 33 kV feeder from Nizwa Grid.Nizwa 2018 Commissioning Stage

To supply the requested load of

ROP Acadmy

No. Referance No. Project Name District Expected


1CC/27/2015 Construction of Aseelah IWP 2x6 MVA primary

substationJalan BB Ali 2018 Commissioning Stage


IWP for water project in Jalan

BB Ali area

2CC/08/2016 Construction of ROP Headquarter 3x6 MVA primary

substation with one dedciated 33kV feeder in Sur areaSur 2019 Designing Stage

To supply the requested load

from ROP for a Headquarter in

Sur area

3CC/05/2014 Construction of Sur ROP 3x6 MVA primary

substation in Sur areaSur 2019 Designing Stage


ROP buildings in Sur area

4CC/28/2015 Construction of Diar Ras Al Hadd 2x20 MVA primary

substation in Sur areaSur 2019 Designing Stage


Diar Ras Al Hadd in Sur area



20

18

-

2

02

0

Table 15: Sponsor Project in South Al Batinah

No. Offer No. Project Name District Expected


1 CC/22/2015

Construction of Suwaiq ROP 2x6 MVA substation to fed

New ROP project with new 33 kV feeder from Khadra

Grid and link from Marble Factory 33 kV feeders

Suwaiq 2018 Execution stageTo supply the requested load of

ROP Suwaiq

2 CC/12/2014South Al Batinah Logistics 1x6 MVA substation to feed

the Logistics area at Nakhal area.Nakhal 2018 Execution stage


South Al Batinah Logistics

3 CC/04/2015Constructing two 2x20MVA substations for Barka IWP

with two 33kV feeders from Hai Asem Grid Barka 2018 Commissioning Stage


Barka IWP

4 CC/10/2016Construct a new 3x6 MVA substation to supply the

sponsor project of ROP Wadi Al Mawel complex.Nakhal 2018 Execution stage


ROP Wadi Al Mawel

5 CC/4/2017Construction of Barka Water Pump Temp. 1x6 MVA

substationBarka 2018 Execution stage


Barka Water Pump

6 CC/4/2016Construction of Rustaq Sport Cmplex Temp. 1x6 MVA

substationRustaq 2018 Execution stage


Rustaq Sport Cmplex

7 CC/4/2017Construction of Barka Water Pump 2x20 MVA substation

with two 33 kV feeders from Hai Asem GridBarka 2019 Designing Stage


Barka Water Pump

8 CC/5/2017Construction of Al Hazam Water Pump 2x6 MVA

substation with 33 kV feeders from Muladah GridMusnah 2019 Designing Stage


Al Hazam Water Pump

9 CC/7/2016

Construct Sandan 3x6 MVA substation with two

dedicated 33kV feeders from Madinat Barka-A grid

station

Barka 2019 Designing StageTo supply the requested load of

Sandan project



20

18

-

2

02

0

Table 16: Sponsor Project in North Al Sharqyiah

No. Referance No. Project Name District Expected


1

CC/14/2014 Construction of Ibra ROP 2x6 MVA primary substation Ibra 2018 Commissioning StageTo supply the requested load of

ROP buildings in Ibra area

2

CC/22/2014 Construction of Al Zain Poultry Farm 1x6 MVA

primary substationMudahibi 2018 Commissioning Stage


Al Zain Poultry Farm in

Mudhaibi area



20

18

-

2

02

0

14. Assessment of 33 KV Technical Losses

For the assessment of the technical losses on MZEC’s 33 KV network, the results of the load flow

analysis for the years 2018-2020 i.e. (Summary of Total Generation, Loading & Demand) are used.

The total demand, the apparent losses and the percentage losses for the years 2018-2020 are

shown in Table 17 below.

Table 17 : MZEC’s Total Demand and 33 KV Network Losses 2018-2020

No. Year Governorate Total

Demand (MW)

Total Losses (MW)

Percentage Losses (%)

1 2018

Al Dakhliyah 669.10 17.14 2.56

North Sharqiyah 344.44 14.66 4.26

South Sharqiyah 425.43 9.67 2.27

South Batinah 1000.11 18.90 1.89

Total : 2439.08 60.36 2.47

2 2019

Al Dakhliyah 701.26 16.40 2.34



South Batinah 1084.10 19.55 1.80

Total : 2625.23 61.02 2.32

3 2020

Al Dakhliyah 777.40 17.13 2.20



South Batinah 1171.20 17.88 1.53

Total : 2857.35 58.99 2.06

15. Network Suitability for New Connections

Taking a glance at the Equipment Loadings shown Annexure 1-A-1, 1-A-2, 1-B-1, 1-B-2, 1-C-1, 1-

C-2,1-D-1 and 1-C-2, it is seen that the 33 kV network and its components will be partially relieved

by the reinforcements programs. Despite the fact that for simple new connections which are defined

in the approved connection statement as those connections with a distance of less than 1.5 kilometer

and with a connected load of 2.5 MW or less, MZEC will not stop any application because of network

capability. On the other hand, for complex connections, the situation is totally different. In many

locations the network requires investments at grid level either in terms of additional capacity or

availability of circuit breakers. Further constraints are also at primary substations and 33 kV feeders

driven by the considerable growth experienced especially at the coastal part of South Al Batinah

Governorate, Nizwa in Al Dakhilyiah Governorate and parts of Al Sharqyiah (South and North)

Governorates.

Having said that, it is worth mentioning that a lot of uncertainty accompanies complex customers’

applications in terms of load and time for connections. Many applications were received since last

year capability statement and the seriousness of some is questioned. An example to that, a new

industrial area in Sumail requires large loads within a timeframe of few years which might require

investment at transmission network. On the other hand, such investment requires commitment from

applicants as well as accuracy in their applications. MZEC in this regard proposes to establish a



20

18

-

2

02

0

mechanism to filter serious applicants from non-serious applicants. Once this mechanism is

approved and implemented, it will contribute significantly to plan for future investments.

The required reinforcements and the loadings of equipment shown in Annexure 1-A-1, 1-A-2, 1-B-1,

1-B-2, 1-C-1, 1-C-2, 1-D-1 and 1-C-2, give a clear picture of the anticipated constraints that may be

imposed on the 33 KV network. The load flow results for the years 2018, 2019 and 2020 are obtained

on the assumption that the current ongoing projects (CWIP) are completed on time and the planned

reinforcements are also delivered on time. Failure to finance these reinforcements or delay in timely

completion will impose further constraints on the network for the years 2018, 2019 and 2020.

16. Constraints

The required reinforcements and the loadings of equipment shown in in Annexure 1-A-1, 1-A-2, 1-

B-1, 1-B-2, 1-C-1, 1-C-2, 1-D-1 and 1-C-2 give a clear picture of the anticipated constraints that may

be imposed on the 33 KV network. The load flow results shown for the years 2018, 2019 and 2020

were obtained on the assumption that the current ongoing projects (CWIP) are expected to be

completed on time and the planned reinforcements are financed to bring them into operation. Failure

to finance these reinforcements or delay in timely completion will impose constraints on the network

for the three years.

distribution system capability statement - mzec.nama.om · distribution system capability statement...

Documents