NS194 Protection Requirements of Embedded Generators >30kW

December 2013

Amendments from: NSA1746 Jan 2014

SUMMARY

Network Standard NS194 outlines the requirements an Embedded Generator should fulfil when connecting to the Ausgrid’s network.

ISSUE

For issue to all Ausgrid and Accredited Service Providers’ staff involved with the connection of Embedded Generators to the network, and is for reference by field, technical and engineering staff.

Ausgrid maintains a copy of this and other Network Standards together with updates and amendments on www.ausgrid.com.au.

Where this standard is issued as a controlled document replacing an earlier edition, remove and destroy the superseded document.

DISCLAIMER

As Ausgrid’s standards are subject to ongoing review, the information contained in this document may be amended by Ausgrid at any time.

It is possible that conflict may exist between standard documents. In this event, the most recent standard shall prevail.

This document has been developed using information available from field and other sources and is suitable for most situations encountered in Ausgrid. Particular conditions, projects or localities may require special or different practices. It is the responsibility of the local manager, supervisor, assured quality contractor and the individuals involved to ensure that a safe system of work is employed and that statutory requirements are met.

Ausgrid disclaims any and all liability to any person or persons for any procedure, process or any other thing done or not done, as a result of this Standard.

Note that compliance with this Network Standard does not automatically satisfy the requirements of a Designer Safety Report. The designer must comply with the provisions of the WHS Regulation 2011 (NSW - Part 6.2 Duties of designer of structure and person who commissions construction work) which requires the designer to provide a written safety report to the person who commissioned the design. This report must be provided to Ausgrid in all instances, including where the design was commissioned by or on behalf of a person who proposes to connect premises to Ausgrid’s network, and will form part of the Designer Safety Report which must also be presented to Ausgrid. Further information is provided in Network Standard (NS) 212 Integrated Support Requirements for Ausgrid Network Assets.

INTERPRETATION

In the event that any user of this Standard considers that any of its provisions is uncertain, ambiguous or otherwise in need of interpretation, the user should request Ausgrid to clarify the provision. Ausgrid’s interpretation shall then apply as though it was included in the Standard, and is final and binding. No correspondence will be entered into with any person disputing the meaning of the provision published in the Standard or the accuracy of Ausgrid’s interpretation.

Network Standard NS194

Protection Requirements of Embedded Generators >30kW December 2013

CONTENTS

1 SCOPE ........................................................................................................................ 1

2 REFERENCES ............................................................................................................ 1

3 APPLICATION FOR CONNECTION............................................................................ 3

4 EARTHING .................................................................................................................. 3

5 PROTECTION REQUIREMENTS................................................................................ 4 5.1 Network and LoM Protection System Redundancy ......................................... 7 5.2 Neutral Voltage Displacement (NVD) .............................................................. 7 5.3 Network and LoM Circuit Breaker Fail ............................................................. 7 5.4 Over and Under Voltage Protection ................................................................. 8 5.5 Over and Under Frequency Protection ............................................................ 8 5.6 Parallel Operation and Check Synchronisation (CS)....................................... 8 5.7 Fault Levels and Ausgrid Scheduling............................................................... 9 5.8 Loss of Mains (LoM) /Anti-Islanding................................................................. 9 5.9 Intertrip Communications Link........................................................................ 10 5.10 Automatic Switching and Reclosing............................................................... 10 5.11 Generator Automatic Reconnection............................................................... 10 5.12 Relay and Tripping Supplies .......................................................................... 11 5.13 Sydney Triplex Network ................................................................................. 11 5.14 Connection arrangement examples ............................................................... 11 5.15 Relay Requirements....................................................................................... 11 5.16 Approval of Protection Schemes.................................................................... 12

6 COMMISSIONING AND AUSGRID WITNESS TESTING.......................................... 13

APPENDIX 1 – SAMPLE PROTECTION SCHEMES .......................................................... 14

APPENDIX 2 – AUSGRID APPROVED PROTECTION RELAYS ....................................... 18

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1 SCOPE

This document outlines the protection system requirements for connection of Embedded Generation of greater than 30kW* to the Ausgrid network.

It does not deal with the protection requirements for network connected micro size generators less than 30kW 3-phase or 10kW per phase or synchronised close transfer systems which should comply with AS 4777 -2002 and the 2007 Service and Installation Rules of NSW particularly Section 8, Alternative Sources of Low Voltage Supply.

For example, an installation which consists of 4 separate arrays of PV, each having a capacity of 10kW would be subject to the requirements of this Network Standard, as the total electrical output of the installation is 40kW.

*The size of generator is defined as the combined total electrical output of all generating units at the point of connection.

2 REFERENCES

Electrical construction works on Ausgrid’s low voltage and high voltage distribution systems must be carried out in accordance with Ausgrid’s Supply Connection and Network Standards and Australian Standards which include but are not limited to the following:

ES 1 Premises Connection Requirements

ES 3 Metering Installations

ES 11 Requirements for the Connection of Embedded Generators

ENOS Electricity Network Operating Standards

Policy for ASP/1 Premises Connection

Connection Policy – Connection Charges

NS116 Design Standards for Distribution Earthing

NS 194A Guidelines for Photovoltaic installations up to 200kW connected via inverters to the Ausgrid network

NS 194B Guidelines for synchronous and asynchronous machines connected to the Ausgrid network.

Generator Connection Agreement: General Conditions

The latest edition of the Service & Installation Rules of NSW

Ausgrid’s Electrical Safety Rules

Australian Standards such as:

AS/NZS 3000- Electrical Installations (Wiring Rules), 3010 – Electrical Installations – Generating Sets, 3017 – Testing Guidelines

AS/NZS 3008 - Electrical Installations – Selection of Cables

AS 4777-2005 - Grid Connection of Energy Systems via Inverters, Parts1, 2, 3

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AS5033: Installation of Photovoltaic Arrays AS 2467 – Maintenance of Electrical Switchgear

AS – 60038-2000 – Standard Voltages

AS/NZS 4853:2012- Electrical Hazards on metallic pipelines

AS/NZS 3835:2006 –Earth Potential Rise – Protection of telecommunications network users, personnel and plant. Part 1 – Code of Practice

AS6100.3.2: Electromagnetic Compatibility – Limits for Harmonic Current Emissions

AS/NZS 61000.3.6 – Electromagnetic Compatibility (EMC) –Limits – Assessment of emission limits for distorting loads in MV and HV power systems.

AS/NZS 61000.3.7 – Electromagnetic Compatibility (EMC) –Limits – Assessment of emission limits for fluctuating loads in MV and HV power systems

Other references:

ENA DOC 001-2008 National Electricity Network Safety Code

ENA EG-0:2012 – Power System Earthing Guide Pt:1 Management Principles

IEEE PSRC Intertie protection of consumer-owned sources of generation, 3MVA or less

IEEE 1547 IEEE Standard for interconnecting Distributed Resources with Electric Power Systems

BCSE Technical Guide for Connection of Renewable Generators to the local Electricity Network

IEC 61000-3-14 “Assessment of emission limits for the connection of disturbing installations to LV power system”

IEC 60255 Measuring Relays and Protection Equipment Requirements

ENA ENA Guideline for the preparation for connection of Embedded Generation within Distribution Networks – May 2011

Legislative and Electricity Market requirements:

NER National Electricity Rules, including Central despatch and Integration of Wind and Other Intermittent Generation Rule 2007.

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3 APPLICATION FOR CONNECTION

For procedure regarding the application for connection of generator greater than 30kW refer to ES-11 Requirements for Connection of Embedded Generators.

4 EARTHING

The customer is required to ensure that the generator installation has an earthing system that has been designed to limit any step, touch and transferred potentials to safe values using the principles detailed in “ENA EG-0:2012 – Power System Earthing Guide Pt1: Management Principles”. Equipment used to interface to the distribution network (e.g. step up transformer or circuit breaker) must comply with NS116 – Design Standards for Distribution Earthing.

Additionally the earthing system of the Generator must be designed to limit the voltages impressed onto surrounding utility infrastructure under earth fault conditions. For metallic pipelines the tolerable voltages are listed in AS/NZS 4853:2012 and for telecommunications assets the voltage limits are found in AS/NZS 3835:2006.

Generation schemes working in parallel with the distribution network in effect become an integral part of the electricity distribution network. Therefore neutral earthing arrangements for the private generators and any interconnection transformers must be designed to suit the requirements of both the distribution network and the customer’s generation installation and details provided to Ausgrid.

High Voltage Generators

The generator’s high voltage star point must be effectively isolated from earth (i.e. isolated or earthed via a high impedance) to avoid any earth fault contributions flowing into the Ausgrid system and to inhibit the flow of harmonic currents through the neutral. Each case will be discussed with the Customer on its merits.

Low Voltage Generators

Generators connected to the network via a delta/star transformer with the delta on the network side may have their neutral directly connected to earth (i.e. via an MEN link).

Effective isolation of this neutral may be required to inhibit the flow of harmonics through the neutral and the generator’s method to limit harmonics must be discussed and agreed to by Ausgrid. The use of 4-pole switching may be required if the generator can operate in standby mode.

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5 PROTECTION REQUIREMENTS

Protection systems for embedded generating units operating in parallel with the grid can be divided into the following two main categories as described below. This standard only covers the requirements for Network and Loss of Mains (LoM) protection systems for embedded generators and does not cover the requirements for short circuit protection systems in customer installations.

As required by NER Schedule 5.2.2, a “Generator must only apply settings to a control system or a protection system that are necessary to comply with performance requirements of schedule 5.2 if the settings have been approved in writing by the relevant Network Service Provider and, if the requirement is one that would involve AEMO under clause 5.3.4A(c) of the Rules, also by AEMO. A Generator must not allow its generating unit to supply electricity to the power system without such prior approval.”

Ausgrid will require all protection system schematics, relays and settings for the generator protection systems described within this document as listed in Tables 4.1 and 4.2 to insure the installation complies with this standard. All protection equipment must be tested and commissioned by a competent person to the agreed settings and a Certificate of Compliance issued to Ausgrid prior to connection to the Ausgrid network. The customer is to keep written records of all protection settings and test results. A copy is also required by Ausgrid.

Short Circuit protection (Not covered in this standard)

Systems installed to protect equipment (the generating units and the power system) against short-circuit faults.

The requirements for these systems in LV installations are not covered in this standard, they are covered in AS3000.

The requirements for these systems in HV installations will be determined on a case by case basis depending on the connection arrangement. Requirements for short circuit protection are covered elsewhere in Australian and Ausgrid Standards.

Protection dealing with normal short-circuit faults is required, as for any customer connection, but may need some special treatment to allow for multiple sources of active power onto the network. Even if the generator is not a source of short-circuit current, adequate short circuit protection is necessary as for any Customer installation.

Network and Loss of Mains (LoM) protection (Covered by this standard)

Systems installed to ensure the network is operating within the limits of its design and that uncontrolled ‘islands’ can not be formed between the generator and the local or interconnected network. This standard specifically covers the requirements for these types of protection schemes.

Protection shall be designed in accordance with the applicable regulations and

Ausgrid’s standards and network engineering guidelines, which require a main and back-up set of protection to detect all credible Islanding Conditions. The protection systems must include sufficient redundancy to ensure that the generator/s disconnect from the network with any single protection element out of service or if any single circuit breaker fails to operate. This will require a main and backup protection scheme.

The protection schemes required are dependent on the type of generating units and the point of connection to Ausgrid’s network. See Tables 5.1, 5.2 following.

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Table 5.1: Inverter-connected Generator Protection Requirements

Protection and Associated Reference

Reference Section

Low Voltage Connection Point (415V)

High Voltage Connection Point (11kV and above)

Common Requirements

AS4777 compliant inverters (Note 2, Note 3)

5.1 M M

Neutral Voltage Displacement 5.2 Refer Sect 5.2 M

Under voltage and Overvoltage 5.4 M M

Under frequency and Over frequency

5.5 M M

Ausgrid scheduling 5.7 Refer Sect 5.7 Refer Sect. 5.7

No Export Generator Requirements (Note 1)

Grid Reverse Power 5.8 M1 (P) M1 (P)

Grid Low Forward Power 5.8 M2 M2

Export Generator Requirements

Intertrip 5.8/9 M1 (P) M1 (P)

ROCOF and Vector Shift 5.8 M2 M2

Legend

M: Mandatory

M1, M2 Mandatory with alternative - select either ‘M1’ or ‘M2’ to suit the connection. Option marked with (P) is preferred.

Note 1: In circumstances where reverse power and low forward power are not suitable for use with No Export Generators, Intertrip or Vector Shift and ROCOF LoM protection, as per Export Generator Requirements, can be provided by agreement with Ausgrid.

Note 2: Inverters which are not AS4777 compliant will be required to be assessed on a case by case basis.

Note 3: The AS4777 Inverters provide the main Network and LoM protection, so the protection functions listed in Table 5.1 are the back-up protection requirements. Refer to Section 5.1.

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Table 5.2: Synchronous Machine and Asynchronous Machine Generator Protection Requirements

Protection and Associated Reference

Reference Section

Low Voltage Connection Point (415V)

High Voltage Connection Point (11kV and above)

Common Requirements

Neutral Voltage Displacement 5.2 Refer Sect 5.2 M

Circuit Breaker Fail 5.3 M M

Duplicate Under voltage and Overvoltage

5.4 M M

Duplicate Under frequency and Over frequency

5.5 M M

Synchronising* 5.6 M M

Ausgrid scheduling 5.7 Refer Sect 5.7 Refer Sect. 5.7

No Export Generator Requirements (Note 1)

Grid Reverse Power and Grid Low Forward Power

5.8 M1 (P) M1 (P)

Duplicate Grid reverse power 5.8 M2 M2

Export Generator Requirements

Intertrip 5.8/9 M1 (P) M1 (P)

Duplicate ROCOF and Vector Shift 5.8 M2 M2

Legend

M Mandatory

M1, M2 Mandatory with alternative - select either ‘M1’, ‘M2’ to suit the connection. Option marked with (P) is preferred by Ausgrid.

* Asynchronous machines do not require synchronising facilities.

Note 1: In circumstances where reverse power and low forward power are not suitable for use with No Export Generators, Intertrip, Vector shift and ROCOF LoM protection, as per the Export Generator Requirements, can be provided by agreement with Ausgrid.

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5.1 Network and LoM Protection System Redundancy Where noted as ‘Duplicate’, it is a requirement that the Network and LoM protection systems as listed in Table 5.2 are duplicated in the form of Main and Back-up such that any single failure of the protection system, including relays, circuit breakers, power supplies etc will not prevent intended operation of the protection system.

For Inverter connected generators

In a large array of PV, if all inverters are compliant with AS4777, then the on board systems in the AS4777 compliant Inverters would constitute the Main Protection for the Common Requirements and No Export or Export requirements. Therefore, the AS4777 compliant Inverters only require a single overall Back-up Protection, as per Table 5.1 to meet the requirements of this standard. See Example 1 in Appendix 1.

Synchronous and Asynchronous Generators

Duplicate (Main and Back-up) LoM Protection as per Table 5.2 will be required to be provided. See Example 2 in Appendix 1.

5.2 Neutral Voltage Displacement (NVD) Considering the earthing arrangements and the use of delta-star transformer windings throughout Ausgrid’s distribution network, detection of an 11kV (or other distribution voltage) network earth-fault on the delta-side of the transformer may be problematic for generator installations.

While the fault-current contribution from Ausgrid will be interrupted by the opening of appropriate circuit-breakers, there remains the possibility that a generator may still energise the faulted distribution network without fault current flowing (due to the loss of Ausgrid’s earth reference). As such, the generator must not remain connected to the system if this type of situation arises because of the safety and legal implications.

The most reliable detection technique for this situation is Neutral Voltage Displacement (NVD) using voltage transformers connected to the 11kV (or other distribution voltage) system. Particular attention is needed to ensure that the voltage transformers (VTs) are of the correct configuration/type for use with this form of protection.

The installation of NVD will be assessed and negotiated on the merits of the proposed generator connection point. For generators that have a low-voltage connection point, it is acknowledged that an 11kV VT connection point may not be readily available for the customer to provide NVD Protection. In such cases, the location and responsibility of the installing VTs will be negotiated during the assessment process. For example, Ausgrid may request NVD be installed and provide a VT supply to the customer to enable NVD to be implemented.

Settings for NVD are to be negotiated with Ausgrid on a case by case basis.

5.3 Network and LoM Circuit Breaker Fail The LoM and anti-islanding protection systems must make allowance for circuit breaker fail (CBF) scenarios in their design.

The form of CBF protection is subject to agreement with Ausgrid, but would normally require the Main LoM Protection and the Back-up LoM Protection to trip/open independent circuit breakers/contactors, or by a dedicated CBF protection scheme.

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For AS4777 Inverter connected generators

The Inverters themselves provide one of the required Circuit Breakers/Contactors. Therefore the back-up LoM protection, as per table 5.1, is only required to trip a single Circuit Breaker/Contactor.

For synchronous Generators

It is typical for the main LoM protection and the back-up LoM protection to trip/open independent Circuit Breakers/Contactors. Alternatively a dedicated CBF scheme can be provided.

5.4 Over and Under Voltage Protection Main and Back-up Over Voltage and Under Voltage protection must be provided. All settings are to be agreed upon by Ausgrid. In the case of Low Voltage AS4777 Inverter Connected Generators, the main protection is that within the Inverter.

Indicative maximum settings for the backup protection are:

LV Connected Over Voltage: 467V phase to phase (270V phase to neutral)

Maximum 2 second operation time

LV Connected Under Voltage: 346V phase to phase (200V phase to neutral)

Maximum 2 second operation time

NB: Main Over Voltage protection settings should be in accordance with the Service and Installation Rules of New South Wales August 2012, which requires an Over Voltage setting of 260V. In the case of AS4777 Inverter connected generators, 260V is the Over Voltage requirements of the Inverter protection.

All other main protection settings are to be at least as sensitive and at least as fast as the back-up protection settings.

5.5 Over and Under Frequency Protection Main and Back-up Over frequency and Under frequency protection must be provided. All settings are to be agreed upon by Ausgrid. In the case of AS4777 Inverter Connected Generators, the main protection is that within the Inverter.

Indicative maximum settings for the backup protection are:

Over Frequency: 52Hz

Maximum 2 second operation time

Under Frequency: 48Hz

Maximum 2 second operation time

Main protection settings are to be at least as sensitive and at least as fast as the back-up protection settings

5.6 Parallel Operation and Check Synchronisation (CS) It is of paramount importance that parallel operation does not present a hazard to Ausgrid staff, public or the customer utilising the generation plant. Consequently, it is necessary for a failure of supply or irregularity in any of the phases of the Ausgrid network to which the private generator is connected to result in the complete and automatic disconnection of the private generator from the Ausgrid network.

The generator cannot connect to Ausgrid’s network unless all phases of the network are energised in a healthy state. At the switching point to make the parallel connection between the generator and Ausgrid’s network either synchronisation, or zero voltage on the generator side of the connection point must be checked before

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allowing closure of the switching point to parallel the generator with Ausgrid’s network or energise the customers equipment from the switching point. This is of particular importance at any switching point which can be configured to provide automatic reconnection of the generator as per Section 5.11.

5.7 Fault Levels and Ausgrid Scheduling Since existing Ausgrid network and substations were designed and constructed without consideration for embedded generation, additional sources of supply will affect the fault-level on the Ausgrid network. As the penetration of embedded generation continues, a point may be reached where additional sources of supply will result in the fault-level being greater than the switchgear and equipment rating.

Ausgrid therefore reserves the right to inhibit the output of a generator to ensure that the system is not compromised under high-fault level or abnormal conditions. This may be provided via a control signal from Ausgrid such that the generating unit is either taken off-line (i.e. a ‘soft-trip’) or inhibited from starting up.

Upon assessment of the proposed connection, Ausgrid will advise the customer if any fault level exist whereby scheduling may be required as part of the installation.

5.8 Loss of Mains (LoM) /Anti-Islanding The generator must be disconnected whenever the local network is disconnected from the grid. Anti-islanding devices are required to operate quicker than 1 second less than the connected feeder automatic reclosing time to a maximum of 4 seconds (see Sect. 4.10).

There must be two independent LoM Protection schemes, i.e. duplicate schemes (or Main and Back-up schemes) as per Table 5.1 and 5.2. and Section 5.1

Non-exporting generators:

For generators which are not intended to export power to the Ausgrid network, Grid Low Forward Power (GLFP) and/or Grid Reverse Power (GRP) Protection is preferred, however alternate LoM Protection, as per Table 5.1 and 5.2, can be provided as agreed by Ausgrid. Settings and details of Grid Low Forward/Reverse Power Protection are to be negotiated with Ausgrid on case by case basis.

NOTE: Grid Reverse Power Protection is not the same as Generator Reverse Power Protection.

Exporting generators:

For generators that intend to export power to Ausgrid’s Network, it is preferred for intertripping to be implemented. Alternatively a combination of Vector Shift (VS) and ROCOF LoM protection can be provided as per Table 5.1 and 5.2.

All settings are to be agreed upon by Ausgrid.

Indicative maximum settings for the main and backup protection are:

Vector Shift: 8 degrees for strong city/urban networks, up to 12 degrees for weak rural networks

ROCOF: 1.0 Hz/sec 1 second definite time delay

(Main protection settings are to be at least as sensitive and at least as fast).

NOTE: Primary testing of the LoM Protection schemes will be required to confirm the adequacy of the VS and ROCOF settings chosen, this may result in alteration of settings to be more sensitive in some cases. See Section 5.

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Ausgrid will be required to approve all Loss of Mains/anti-islanding protection systems, including which protection trips which circuit breakers to ensure the CBF requirements of this standard have been met. When the sensitivity of LoM protection (as per Table 5.1 or 5.2) can not be demonstrated to be adequate, or where the LoM protection is inappropriate, another form of LoM will be required to be installed. Any LoM scheme shall be implemented on a three-phase basis to ensure adequate performance.

Regardless of the type of LoM installed, the generator proponent and customer must accept that LoM/anti-islanding protection may not be able to be set to discriminate with other protection systems on the Ausgrid network. Therefore the generator proponent and customer must accept that the generating units may trip for system disturbances and fault events both within and external to the local network that the generator is connected to. This is particularly relevant for Vector Shift and Rate of Change of Frequency (ROCOF) protection where experience has shown setting of these schemes to be difficult to avoid nuisance tripping while providing adequate protection.

It is recommended that proponents design protection and control systems where the main and backup LoM protection trips circuit breakers/contactors which only control the generator and do not control other loads within the system. Therefore, any nuisance tripping as described above will not cause a loss of supply to the customer, in particular to any critical loads.

5.9 Intertrip Communications Link If a communication link is installed between the embedded generator and Ausgrid to facilitate an intertrip or scheduling it must be continuously monitored for integrity. In the event that the communication link fails then the generator must be automatically disconnected from Ausgrid’s network until the link is restored. This provides a fail safe design which requires no back-up LoM type protection.

The provisions of the NER may require some diversity in communication depending upon the installation.

5.10 Automatic Switching and Reclosing The majority of Ausgrid feeders are programmed for automatic re-closing after a period of between 3 seconds and 10 seconds after the successful clearance of a feeder fault depending on the specific fault location.

Ausgrid Zone Substations are generally fitted with auto-closing to cover for loss of Zone Transformers and related plant with an automatic restoration time of between 5 and 10 seconds.

Failure of the customer’s equipment to disconnect prior to automatic switching may result in damage not only to Ausgrid’s equipment but also the generation equipment unless it is adequately protected.

5.11 Generator Automatic Reconnection Where the customer has proved automatic reconnection is safe and that generator state is monitored, then automatic reconnection to the network is permitted. The device controlling the automatic reconnection must be able to verify normal supply conditions on the grid for all connected phases (i.e. all three phases for a three phase connection) for a period of at least 1 minute prior to the device enabling an automatic reconnection.

Where there are multiple points of automatic reconnection in the installation, each point must independently be able to monitor and verify normal supply conditions on the grid for all connected phases for a total period of at least 1 minute before enabling automatic reconnection of the Generator to Ausgrid’s network.

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In some installations, as will be nominated by Ausgrid, a manual reset may be required and the generator will not be allowed to be automatically reconnected to the network. Ausgrid will negotiate the requirements of these proposals on a case by case basis with the proponent.

5.12 Relay and Tripping Supplies Unless the requirements outlined in points 1) and 2) below are met, the relay power supplies, tripping and circuitry associated with the Network and LoM protection systems must be fail safe. That is any failure of any part of the system must result in the generator being disconnected and unable to be re-connected to Ausgrid’s network.

Therefore, circuit breakers with shunt trips will not be acceptable. Where ac (or dc) supplies are proposed to be used, normally open contactors held in by healthy ac (or dc) volts or undervoltage release of circuit breakers on loss of ac (or dc) supply, relay fail and system fail will be required.

Alternate arrangements, usually only associated with HV connections, such as a DC system utilising shunt trip circuit breakers for the Network and LoM systems may be accepted with approval by Ausgrid, providing the following 2 points are met.

1) The customer has an approved Installation Safety Management Plan as per Ausgrid Premises Connection Requirements document ES1.

2) Requirements for the ongoing inspection, maintenance and testing of the Network and LoM protection systems are defined within the Generator Connection Agreement applicable to that site.

5.13 Sydney Triplex Network It should be noted that Sydney CBD Triplex network is different to other parts of the Ausgrid distribution area and, due to its complexity will impose different restrictions on the installation of embedded generation.

In particular, there are legacy devices installed at some CBD substations (network protectors) that may prohibit export. Particular attention will need to be paid to synchronisation as there are schemes that remotely initiate the opening and closing of low-voltage circuit-breakers.

5.14 Connection arrangement examples Examples to illustrate some indicative protection arrangements are provided in Appendix 1. There are a large number of possible combinations of generation type, size and connection voltage hence only a representative sample is illustrated. These examples are for information only, and details may be modified as required for specific site conditions.

5.15 Relay Requirements Where applied as per the requirements of this standard, the Network and LoM relays listed in Appendix 2 are approved for use by Ausgrid.

For Inverter connected generators and Synchronous/Asynchronous connected generators with a High Voltage Connection Point (11kV and above), at least one of the required duplicate Network and LoM relays must be compliant with the severity class (of IEC60255) corresponding to the part of the installation in which it is located.

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5.16 Approval of Protection Schemes The following protection drawings must be submitted to Ausgrid for approval:

(a) A 3 phase ac schematic diagram of protection and control systems

(b) A DC schematic diagram of all control and protection schemes and associated logic

(c) Details of primary and secondary interfaces to the network.

(d) Details of all protection and metering CTs and VTs and their connections.

(e) Details of Protection Relay and circuit breakers being proposed

Ausgrid will be required to approve all protection relay settings on the installation and to witness testing by the customer of LoM protection in additional to normal AS3000, AS2067 and NSW Service Rules equipment and protection testing by Ausgrid Installation Inspectors.

Input and outputs of LoM protection relays must be provided with suitable facilities (e.g. isolating links) to allow testing of the LoM relay to be undertaken without the need to disconnect and re-terminate wires. Failure to provide these facilities may cause delays and problems with LoM witness testing.

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6 COMMISSIONING AND AUSGRID WITNESS TESTING

Prior to the >30kW connection of the embedded generator to Ausgrid’s network, Ausgrid will inspect those parts of the generation plant that have a direct effect on the network. Where necessary, Ausgrid may require specific tests to be carried out on the generating plant to prove the integrity of the LoM anti-islanding protection schemes.

The generator proponent must develop in conjunction with Ausgrid to undertake primary testing of the LoM protection. Details of this plan will depend on the system arrangement and point of connection of the generator.

As per specific contract conditions, Ausgrid will require notice to be given be given to allow:

Ausgrid representation during commissioning and all tests that apply to Network and LoM anti-islanding protection

Access to commissioning test results, test plans, details of test methods and protection settings

Connection to network during commissioning tests

Ausgrid representation during Primary testing of Loss of Mains protection including Intertrips, ROCOF, VS and Reverse Power Protection

Testing under and over voltage, frequency etc, generation system protection.

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APPENDIX 1 – SAMPLE PROTECTION SCHEMES

The following are examples of typical connections which meet the requirements of this standard. These are examples only. The specific design will be a function of the customer network and may require different arrangements.

For clarity, only the LoM type protection systems as per this standard are shown. Short Circuit type protection is not shown.

Legend

NVD Neutral Voltage Displacement VS Vector Shift

UF Under Frequency RoCoF Rate of Change of Frequency

OF Over Frequency CS Check Synchronisation

UV Under Voltage GLFP Grid Low Forward Power

OV Over Voltage GRP Grid Reverse Power

Example 1: >30kW Export Inverter connected at 415V

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Example 2: >30kW Export Synchronous Machine connected at 11kV

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Example 3: > 30kW Export Inverter connected at 11kV

Example 4: > 30kW Export Synchronous Machine connected at LV

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Example 5: > 30kW No Export Synchronous Machine connected at 11kV

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APPENDIX 2 – AUSGRID APPROVED PROTECTION RELAYS

When applied as per the requirements of this standard, the following relays are pre-approved to provide protection functions as described in Section 5, Tables 5.1 and 5.2 for Low Voltage connected Generators. Customers may elect to use alternate relays. All relays used for the generator protection systems must be approved for use by Ausgrid.

NOTE: Refer to section 5.15 for IEC60255 compliance requirements for High Voltage connected generator Network and LoM relays.

Manufacturer Model Identifier

AREVA/Schneider P923*, P341

Woodward MFR11

Com Ap MainsPro

Table A2 Approved LoM relays for Low Voltage Connection

* Does not provide Vector Surge function, additional relay may be required.

Ausgrid.

This document must not be reproduced in whole or in part or converted to machine readable form or stored in a computer or imaging system without the written permission of Ausgrid.

Revision History

Initial issue:

Last issue:

This Issue:

29/08/2008

29/08/2008

01/12/2013

Document Control

Authorised By: Date: 01/12/2013

Terry Lampard, Manager – Standards & Communications

Document Number: NS194