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D e c e m b e r 2 0 1 1

Draft Network Code

“Requirements

for

All

Generators”

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

A EURELECTRIC DSO Position

Published with Support of GEODE & CEDEC



The Union of the Electricity Industry–EURELECTRIC is the sector association representing the common interests of

the electricity industry at pan‐European level, plus its affiliates and associates on several other continents.

In line with its mission, EURELECTRIC seeks to contribute to the competitiveness of the electricity industry, to

provide effective representation for the industry in public affairs, and to promote the role of electricity both in the

advancement of society and in helping provide solutions to the challenges of sustainable development.

EURELECTRIC’s formal opinions, policy positions and reports are formulated in Working Groups, composed of

experts from the electricity industry, supervised by five Committees. This “structure of expertise” ensures that

EURELECTRIC’s published documents are based on high‐quality input with up‐to‐date information.

For further information on EURELECTRIC activities, visit our website, which provides general information on the

association and on policy issues relevant to the electricity industry; latest news of our activities; EURELECTRIC

positions and statements; a publications catalogue listing EURELECTRIC reports; and information on our events and

conferences.

Dépôt légal: D/2011/12.105/56

EURELECTRIC pursues in all its activities the application of

the following sustainable development values:

Economic Development

Growth, added‐value, efficiency

Environmental Leadership

Commitment, innovation, pro‐activeness

Social Responsibility

Transparency, ethics, accountability



Draft Network Code “Requirement for All

Generators”

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

TF Grid Connection Codes

Jacques MERLEY (FR) Chair

Alberto CERRETTI (IT); Bruno GOUVERNEUR (BE); Tony HEARNE (IE); Riccardo LAMA (IT); Johan

LUNDQVIST (SE); Graeme VINCENT (GB); Siegfried WANZEK (DE)

Contact:

Pavla

MANDATOVA,

Advisor,

Networks

Unit‐

[email protected]



1

TABLE OF CONTENTS

Executive Summary ...............................................................................................................2 Introduction...........................................................................................................................3

1. What is a “cross‐border network issue”?..........................................................................4 2. Various types of generators, various roles in European power systems .........................6 3. Various types of generators, various ways to ensure compliance.................................10 4. An open and evolutionary process rather than a state of the art document.................11 5. In‐depth involvement of DSOs to further revision of the document..............................11



2

Executive Summary

In November 2011, ENTSO‐E released a new version of its working draft Network Code on

Connection Requirements Applicable to All Generators. EURELECTRIC welcomes improvement in the

new draft related to the no longer mandatory applicability of network code requirements to existing

plants. Nevertheless, EURELECTRIC DSOs feel the need to address their prevailing concerns about

the

scope

and

the

structure

of

the

working

draft

before

the

code

enters

the

public

consultation

planned by the end of January 2012.

The aim of this report is to present an alternative view on the rationale behind the draft. The

operation of DSO networks entails specific complexities, especially as DSO networks move from a

wholly demand‐dominated model to one where generation and demand have to be balanced to

some extent. The proposals hereby presented build on DSOs experience with network operation,

connection of an increasing number of generators at HV, MV and LV grids and development of the

related connection rules at national level.

The paper seeks to provide an explanation of the term ‘cross‐border network issue’. EURELECTRIC

DSOs believe that in order to comply with the goals of the Third Energy Package, to deal efficiently

with issues affecting cross‐border trade, the EU network code for grid connection of generators

should strictly and exclusively focus on issues that are directly cross‐border ones. The concept of

‘cross‐border network issue’ should be understood as the ensemble of effects related to

characteristics of the electric system, whether dynamic or static, where a local event or accident

can trigger a cross‐border system risk.

An explanation is given as to how the size and the characteristics of various types of generators

affect their role in the European power system with respect to various system variables. System

parameters listed in the ACER framework guideline are a relevant part of the EU network code but

for technical reasons not all of them have to be applied at the EU level to all sizes of generators.

Cross‐

border

impact

of

small

generators

connected

to

distribution

networks

is

limited

to

frequency management. Hence, substantial reduction of requirements for small generators and to

certain extent also medium size plants is proposed. Other issues should be kept in the framework

of technical standards and grid connection rules at national level, with due respect to the principles

of subsidiarity and proportionality. In this way, possible benefits of harmonisation with respect to

cross‐border issues could be maximised and difficulties with different local grid designs avoided.

The report also underlines that compliance of the smaller facilities should be ensured by

guarantees offered by manufacturers or vendors through type testing based on standards (with

engagement of independent certificators), complemented in some cases with testing and checking

before connection. Preferably, the process for testing and checking is to be defined according to

existing standards

and

national

rules.

Last but not least, emphasis is put on the in‐depth association of DSOs, as operators of networks

to which most of the new generators will be connected in coming years, due to the fact that even

for cross‐border issues across‐the‐board distribution grid design solutions are not always

available. There are numerous technical requirements for connection to distribution networks, as

well as associated commercial, legal and regulatory implications. In addition, the significant number

of connected customers calls for approaches susceptible to being efficiently applied in potentially

millions of individual cases. DSO expertise is essential in this respect.

EURELECTRIC DSOs, as members of the ‘DSO Expert Group’ (consisting of EURELECTRIC, CEDEC &

GEODE), therefore ask for close cooperation with TSOs in the drafting of this and the upcoming

codes in

order

to

ensure

a successful

outcome

of

the

process

in

due

time.



3

Introduction

As emerges from the Third Energy Package, network codes are meant to lay down European‐

wide binding rules for electricity wholesale markets, system operation and grid connection. As

requested by the Heads of State in the February 2011 European Council, the emphasis shall fall

on framework guidelines and network codes necessary to implement the target model of the

European electricity

market

by

2014.

ENTSO

‐E is

the

primarily

responsible

party

for

drafting

the

network codes, whilst ACER is assigned to provide framework.

ENTSO‐E recently released a new version of its working draft Network Code on Connection

Requirements Applicable to All Generators that is together with other foreseen ‘technical

network codes’ for grid connection and system operation considered essential to facilitate the

functioning of the internal electricity market. Since the previous version released in March 2011,

the document has been adjusted in accordance with the final ACER Framework Guidelines

issued by ACER on 20 July 2011. EURELECTRIC warmly welcomes the substantial change related

to the application of the network codes requirements to existing plants (‘retrofitting’ issue)

being no longer mandatory but conditional to a prior positive cost‐benefit analysis at national

level.

Nevertheless, EURELECTRIC DSOs as network operators would like to address their prevailing

concerns about the scope, the structure and the philosophy of the working draft before the

code enters the public consultation planned by the end of January 2012. Even though the share

of distributed generation in Europe is on the rise and that most of the new generators (both in

number and capacity) are due to be connected to distribution networks in the coming years, it

must be noticed that the overall structure of the requirements has been designed without prior

coordination with DSOs. Similarly, very few comments raised by DSO experts in the process

have been taken on board in the newly released version of the code.

Until

recently,

DSOs

have

distributed

power

on

a

top‐down

basis.

With

more

and

more

generation capacities connected to their grids, their role will increasingly move beyond their

traditional role of “building and connecting” towards “connecting and managing”1. In order to

manage the distribution system and to contribute to the stability of the transmission grid, DSOs

will play a different role, like supporting balancing of load and generation and in the smart grids

perspective, possibly influencing dispatching distributed generation or managing voltage

regulation, and if necessary, using ancillary services for generators connected to their grid.

Structure, protection and automation systems as well as operation of distribution networks

(especially at MV and LV level) are completely different from transmission networks. And unlike

transmission

networks,

which

are

relatively

similar

to

each

other,

distribution

networks

may

vary with respect to DSO and grid design. Hence, issues raised by distributed generation differ

from the ones related to generators connected to transmission. The number of these plants and

of customers/producers is also much higher, and the capabilities of the generating facility

operator are widely diverse, ranging from household tenants to industrial operators. For these

reasons, simply extending concepts used in transmission with large scale generation to

distribution networks is usually not the best solution.

The network code should thus cover only the necessary subset of requirements for distributed

generation. This paper aims at explaining the main points that from EURELECTRIC DSO perspective

should be considered by the responsible bodies in order to ensure the successful outcome of the

network code

development

process

in

due

time.

1 EURELECTRIC 10 Steps to Smart Grids, http://www.eurelectric.org/10StepsTosmartGrids/



4

1. What is a “cross‐border network issue”?

The interpretation of the term ‘cross‐border network issue’ is central in understanding the

objectives of the European network codes. ‘Cross‐border network issues and market integration

issues’ for which the network codes should be developed are not precisely defined by the

Regulation (EC) 714/2009. That leaves room for various interpretations of the term.

ENTSO‐E Proposal:

Considering that any two components in the electric system can potentially interact with each

other, ENTSO‐E interpretation includes not only any technical event on the interconnected

network, whether in distribution or transmission, but also any usage of this network that could

have technical or commercial consequences somewhere. According to this logic, “all the

requirements [included in the draft] have a system‐wide impact”.2 In addition, the current draft

calls for EU level harmonisation of technical standards in order to achieve cost efficiencies and

to facilitate markets for equipment.

EURELECTRIC DSOs Position:

The concept of cross‐border issue/effect should be strictly understood as a characteristic of a

network component, or connected apparatus, that allows a common mode action or reaction

to a network disturbance to propagate across borders to a significant fraction of the total

system, adversely and seriously affecting that fraction. In other words, cross‐border issues are

the ensemble of effects related to characteristics of the electric system, whether dynamic or

static, where a local event or accident triggers a cross‐border system risk.

The following

examples

attempt

to

clarify

this

principle.

Cross‐border issue: Frequency management

The frequency of the electrical system is the same for all users connected (in Europe, frequency is

typically maintained at 50 Hz) and the system can only function within a certain frequency range.

When generation exceeds consumption, power system frequency will increase and insufficient

generation to meet demand will result in falling frequency. Large frequency deviations could cause

cross‐border disturbances as the total amount of generation within the synchronous area, including

both large generators and distributed generation, would be potentially affected. This could result in

severe damage to generating equipment, disturbance of supply, etc. European requirements for all

types

of

generators

(including

those connected

at

distribution

level)

are

thus

needed

in

order

to

ensure the security of the whole system and continuity of supply.

Nevertheless, DSOs should be allowed to adapt the frequency range in which the generator

operates in the case when only distribution networks are affected. Possibility to increase

sensitivity of so‐called Interface Protection Relay (IPR) in case of faults on a MV feeder to avoid

island operation of a part of the network is a typical example.

2 See ENTSO‐E Pilot Network Code for Requirements for Grid Connection Applicable to All Generators FAQ, Answer

to FAQ no. 6.



5

Typically non cross‐border issue: Voltage management

Maintaining voltage stability is essential to keep the electric system in good order. Voltage

control is essential to keep the voltage inside the contractual range for customers. However, it is

a variable with a much smaller range of influence than frequency. Only very large generation

facilities directly connected to high voltage feeder can exert a notable effect across borders.

Voltage influence ‘fades’ across long distance feeders, and through different voltage network

levels.

In addition, there is no European‐wide voltage common mode. The criticality of a given facility

contribution to voltage stability is highly dependent on the local network conditions and local

balancing. And in most cases, it is subject to possible trade‐off with local network

reinforcements.

This implies that some requirements must be specified with a severity directly conditioned by

the local network situation and the significance (size and voltage connection) of the facility.

Therefore, it is wise to set voltage management requirements for large facilities connected to

high level voltage in the European network code. However, for smaller facilities it is sufficient to

request that requirements are set at national level while taking into account the diversity of

possible system situations in order to achieve maximum efficiency.

All in all, the EU network code for grid connection of generators should exclusively focus on

issues that are directly cross‐border ones and which could not be attained without regulation

at the EU level.

Other issues should be kept in the framework of technical standards and existing and well‐

functioning grid connection rules at national level, with due respect to the principles of

subsidiarity and proportionality. The political intention to be derived from the Third Package

legislation ‐to deal efficiently with issues affecting cross‐border trade‐, must be correctly

addressed in the network code.



6

2. Various types of generators, various roles in European power systems

ENTSO‐E Proposal:

ENTSO‐E classifies generators according to size and, as far as certain requirements are

concerned, according to their technological characteristics (synchronous, asynchronous modular

etc.)

and

intrinsic

capabilities.

Many of the proposed requirements deal in detail with the performance of generators who are

DSO customers and that often have limited impact beyond given distribution network and, in

most cases, no cross‐border impact.


EURELECTRIC DSOs agree that the achievement of the 2020 targets requires simple and

pragmatic process for connection of renewable generators to the system and lowering barriers

of entry to the business. However, considering the large amount of renewable power that will

be

connected

to

the

network,

TSOs

and

DSOs

all

over

Europe

must

be

able

to

foresee

their

behaviour in relation to their criticality for the system.

The principle of classification used by ENTSO‐E is excellent and necessary to fit the requirements

to capabilities inherent to some technologies and to keep them at an appropriate level of detail

and organisation. However, it should not be used to unnecessarily extend the requirements

beyond issues that are directly cross‐border.

Generator categories should be defined according to generator size considering the possible

role and impact of each category on the system. Size of the generation facility represents an

important criterion when related to various parameters/variables.

Our proposed

classification

as

outlined

below

is

thus

close

to

the

one

proposed

by

ENTSO

‐E,

or

even simpler. Considering that there is no need to regulate facilities that are hardly noticeable

from the network, we set a minimum capacity of 1kW for type A facilities. The capacity

threshold between type A and type B facilities in Continental Europe and Baltic synchronous

areas was extended to 1 MW because no strong argument in favour of an important difference

between synchronous areas was identified in our analysis.

Moreover, we take into account the revised understanding of the ‘cross‐border issue’ concept

with respect to each category.

Type A

Generators connected to low and medium voltage level with a facility capacity between 1kW and 1 MW.

Characteristics:

These generators are always connected at distribution level (exceptionally at transmission).

There are already millions of generators of this type connected in Europe. In many cases

there are also consumers on the same premises. The operator of the facility has no electro‐

technical background and is not even familiar with the idea and implications of being an

operator. Its facility is operated on the ‘connect‐and‐forget’ basis.



7

Cross‐border impact:

The cross border impact is only related to frequency management since this variable is by

nature not border‐bound. The requirements for these generators are based on the ‘add and

do not harm the system’ principle. Thus the only requirement pertinent at European level is

the capability of such facilities to support a wide frequency range in case of disturbance. All

other requirements

should

be

set

at

national

level.

Type B

Generators connected at medium voltage level with a facility capacity between 1 MW and 10 MW.

Characteristics:

They are mostly DSO customers. They are numerous (thousands to tens of thousands) and

the facility operator is aware of being an operator even though he is not necessarily an

electro‐technical specialist.

Cross‐border

impact:

Same as for type A.

For the moment, there are no important differences between requirements for types A and

B pertinent at European level.

Type C

Generators connected at medium to high voltage level with a facility capacity above 10 MW. Characteristics:

They

are

DSO

or

TSO

customers

depending

on

the

organization

of

the

national

electric

system. They are numerous (thousands) and the facility operator is aware of being an

operator and mostly holds electro‐technical expertise, but frequently relies on

manufacturers’ skills as regards the capabilities of its machines.


Their cross‐border impact is related to frequency management since this variable is by

nature not border‐bound. The requirements for these generators are based on the ‘do not

harm the system and offer limited support in case of disturbance’ principle. The

requirements pertinent at European level concern the capability of those facilities to

support

a

wide

frequency

range

and

to

offer

regulating

capacity

to

support

the

system frequency in case of disturbance.

Type D

Generators connected at high to very high voltage with potentially unlimited capacity. Characteristics:

They are TSO and sometimes DSO customers depending on the organization of the national

electric system. They are rather numerous (hundreds to thousands) and they represent

most of the generation capacity in the existing system. The facility operator holds electro‐

technical

expertise

and

often

exerts

a

strong

influence

on

the

initial

idea

of

the

facility

and

its capabilities. This category includes the offshore facilities regardless of their power.



8


Some of the most important facilities can exert an influence on system stability directly

across borders not only for frequency management but possibly also for other variables. The

requirements for these generators follow the ‘do not harm the system, offer extended

support for the defence of system integrity in case of disturbance and provide capacity to

restore the

system

after

large

scale

incident’

principle.

An

extended

set

of

requirements

is

probably pertinent at European level.

EURELECTRIC DSOs believe that this classification is fully in line with the ACER Framework

Guidelines that explicitly ask for definition of requirements for significant grid users with respect

to parameters listed in section 2.1. These system parameters should be part of the EU network

code but only for types of generators for which they are generally relevant with respect to

cross‐border impact. Table 1 outlines cross‐border impact of various system parameters in

relation to generation types.

For instance,

while

the

category

A

&

B

generators

cross

‐border

impact

(and

thus

significance)

is

only related to frequency management, other parameters that have cross‐border impact in

relation to large generators are not relevant at the EU level for types A & B and thus should not

be part of the network code. On the other hand, large generators (type D) can have an impact

on system stability also for other variables, such as voltage stability or inertia.

Table 1: Cross‐border impact of various system parameters in relation to generation types

Parameters listed in

the FG

Type A

LV/MV

(1kW –

1MW)

Type B

MV

(1MW‐10MW)

Type C

HV

>10MW

Type D

EHV

unlimited

Frequency

management

Yes

Limited

response &

automatic

disconnection

Yes

Limited

response &

automatic

disconnection

Yes

Extended

response &

automatic

disconnection

Yes

Extended response

with load

frequency control

Voltage & reactive

power management

No Cross‐

border Impact

No Cross‐

border

Impact

No Cross‐

border

Impact

Yes

Load ‐ frequency control No Cross‐

border

Impact

No Cross‐

border

impact

No Cross‐

border

impact

Yes

Short ‐circuit current No Cross‐

border impact

No Cross‐

border

impact

No Cross‐

border

impact

No Cross‐border

impact

Requirements for

protection devices &

settings

No Cross‐

border impact

No Cross‐

border

impact

No Cross‐

border

impact

No Cross‐border

impact

Fault ‐ride‐through

capability

No Cross‐

border Impact

No Cross‐

border

Impact

No Cross‐

border

Impact

Yes



9

Since they are important at the Relevant Network Operator level, other requirements for types

A, B & C such as voltage level variations, voltage wave shape (harmonics, flickers, short duration

interruption etc.) grounding, signal quality and fault‐ride‐through should rely on regulations that

are proven and efficient, mostly at national level and on the use of standards.

As the share of variable RES in distribution grids increases, DSOs will need more tools to manage

their

grids

from

distributed

generators.

However,

with

respect

to

type

A

&

B,

frequency

response represents the essential requirements needed at European level. Requirements for

other functions, and if necessary ancillary services, should be set with involvement of DSOs in

the national grid codes and regulations.

To sum up, connection rules for distribution grids do not need to be lifted up to the European

level, except when there is a direct cross‐border impact. Reviewing (rewriting, consultation,

publication) of existing (or, when necessary, under development) national or local regulations

that already accurately address the topics would have minimal positive impact on the internal

market and on quality of supply for customers, both users and producers. Furthermore, it would

create legal uncertainty and risks resulting from the necessity to align detailed European wide

rules

with

national

rules

which

must

necessarily

provide

all

details

for

safe

operation

of

the

system in day to day operation. As a result, the global quality of the system would be reduced

(higher costs, lower performances).

Therefore, EURELECTRIC DSOs propose:

• to significantly reduce the scope of requirements for smaller facilities (A&B) and

substantially for medium size (C);

• to limit European level requirements concerning capabilities to offer ancillary services

to equipments connected to high voltage level (D) especially for ancillary services not

related to

frequency.

With

no

prejudice

for

requirements

at

national

level.

In addition, requirements must be expressed functionally at connection point with the

relevant Network Operator and apply to generating facilities rather than to generating units.

The operator of the generation facility should be responsible for transposing the constraints

expressed at connection point to generation units.

Expressing requirements at unit level should be accepted only if really necessary, for instance in

the case when specific capabilities at the unit level are also needed in addition to those at the

connection point in order to ensure that the facility as a whole meets a given requirement, and

not as a tool to refine and increase the requirements.



10

3. Various types of generators, various ways to ensure compliance

Methods to test and monitor compliance of generation facilities also vary in relation to

generation type.

State of

the

Art:

For types A & B connected mostly to distribution grids, the primary responsibility for compliance

with requirements is on the generator side in most countries. Documentation including

verification of compliance is submitted by the generator to the Relevant Network Operator as a

part of the grid connection process. DSOs then can monitor compliance and participate in the

testing although they do not bear legal responsibility for accuracy of the compliance.

Testing by network operator and simulation is used mostly only for larger units connected to the

transmission grid and is inapplicable on distribution networks due to the number of generators.

ENTSO‐E Proposal:

The working draft lays down provisions for compliance testing and simulations of all types of

generators and the obligation for the relevant network operator to regularly assess the

compliance of a generating unit with the requirements under the network code throughout the

lifetime of the power generating facility.


Due to enormous number of connections at MV and LV level in many countries, it is impossible

for DSOs

to

perform

any

compliance

tests

with

the

exception

of

commissioning

ones.

In

order

to avoid costly and lengthy procedures in the case of smaller generation facilities, the current

best practices should be reflected. Generator capabilities should be assessed through type

tests, performed according to well defined testing procedures, in laboratories accredited by

EA (European Co‐operation for Accreditation) (EN 17025). Type tests shall be included in

product standards compliant with the requirements of the network code.

Specifically, we propose the following procedures with respect to different categories.

Type A

The compliance should be ensured by guarantees (e.g. certificates of compliance) given by

manufacturers or vendors through type testing based on standards. Type tests must be

performed in accredited laboratories, with reference to existing product standards or to

connection standards tests. For cases of need, DSOs should be given the option (not an

obligation) to monitor the compliance after connection.

Type B

The compliance should be ensured by guarantees offered by manufacturers through type

testing based on standards, like category A, possibly completed with testing and checking

before connection. The process for testing and checking is to be preferentially defined according

to existing standards and national grid codes and must be limited to main generation plant performances.



11

Type C

Verification of compliance shall rest on guarantees offered by manufacturers through type

testing and/or standards and national grid codes, usually with some testing before connection

and/or simulation. The process for testing and checking is to be preferentially defined according

to existing standards. If this is not possible, it should be defined at national level.

Type D

Verification of compliance shall rest on guarantees offered by manufacturers through type

testing and/or standards, plus testing and simulation before connection possibly with periodical

checks. The process for testing and checking is to be preferentially defined according to existing

standards and national grid codes.

The compliance & simulation chapters of the draft code should be adjusted to take into account

the necessity to rely on standards and/or qualification procedures.

4. An open and evolutionary process rather than a state of the art document

The current working draft describes very precisely the variables on which the requirements are

based or the value span for those variables and the way compliance testing and simulation is to

be carried out as outlined above.

EURELECTRIC DSOs position:

The proposed

document

might

be

outdated

before

it

is

enforced

since

it

addresses

a very

broad

area of performances, with a restricted knowledge of the constraints and possibilities of

distribution networks. Considering the rapidly evolving organisation of the European electric

system, the network codes must be formulated in a flexible way that sets principles for

functionalities, but is open to future developments and designed for smooth implementation at

national level.

EURELECTRIC DSOs thus recommend that

• the present document is limited to essential issues. Other issues are already very well

reflected in existing national regulation (or in regulation to be developed before the

network code

comes

into

force);

• the maintenance and amendment process should be clarified and at best explicitly

included in the code;

• any maintenance should fully respect solutions that had already been implemented as

long as they are in line with the needs.

5. In‐depth involvement of DSOs to further revision of the document

As outlined in section 1, frequency management is undoubtedly a cross‐border issue. Extending

the frequency range in which the generation facilities connected to distribution grids can

operate is

necessary

for

maintaining

frequency

stability.

However,

the

following

example

of

safe

operation rules demonstrates that no easy across the board standardised solutions for actual

settings of the small generation facilities that could be applied in all countries are in place yet.



12

Therefore, DSO expertise should be fully included in the ongoing development and drafting of

the network code.

EXAMPLE: Safe Operation Rules

Conflicts may

arise

from

incompatibility

of

work

safety

rules

and

adoption

of

functionalities

for

system security reasons. Disconnecting all power sources in case of an incident (or before

planned maintenance) is one of the first golden rules in prevention of electrical risk for persons

in network operations. This function is most of the time performed by protection devices

programmed to trip if some variables, like frequency, are out of set boundaries. With respect to

the high safety risks, obligations binding networks operators with very strong individual

responsibilities are laid down in various documents (i.e. national grid codes, labour legislation).

But from a system security point of view, as endorsed by the proposal, a simple and efficient

option is to ask for machines and protections to remain connected through a wider band of

frequency in order to prevent relatively small incidents from spreading into large scale ones.

While the

safety

rule

is

to

trip

in

case

of

any

incident,

the

decisive

factor

for

security

of

supply

is

to remain connected. However, proposed moderation of protection systems by weakening

frequency and voltage based protection settings could lead to an unacceptable increase of

electrical risk in distribution networks in some countries, depending on the adopted protection

strategy and type of generation. If implemented without due care, the requirements could

under certain circumstances (e.g. islanded operation) cause damage to generators and

consumer appliances.

Requirements with implications for protection settings at the grid connection point for the

generators connected to LV and MV networks may in some countries raise technical issues with

important

technical,

legal

or

financial

consequences

for

DSOs.

Abiding

the

wider

frequency

range requirements without any precaution could result in strong adverse effects on the quality

and operational safety to which DSOs are legally and financially committed in their day to day

operation.

EURELECTRIC DSOs position:

Although frequency requirements are needed to address cross‐border issues, potentially robust

adverse effects on functions, such as protections using frequency variation in their activation

routines, need to be taken into account. A suitable solution has to be found in order to enable

DSOs to

fulfil

their

requirements

to

ensure

the

quality

and

safety

of

networks

operation.

Therefore, it is essential that DSOs are fully included in the future development and drafting of

the network code so that the final draft is compatible with existing and future DSO practices for

both demand and generation.



Union of the Electricity Industry ‐ EURELECTRIC aisbl

Boulevard de l’Impératrice, 66 ‐ bte 2

B‐

1000 Brussels

•

Belgium

Tel: + 32 2 515 10 00 • Fax: + 32 2 515 10 10

VAT: BE 0462 679 112 • www.eurelectric.org

nc on generator connection dsopaper final3 2011 030 1073 01 e

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