SIST-TS CLC/TS 50549-1:2015

Requirements for the connection of generators above 16 A per phase - Part 1: Connection to the LV distribution system

The purpose of this Technical Specification is to provide technical guidance on the requirements for
generating plants which can be operated in parallel with a distribution network.
For practical reasons, this Technical Specification refers to the distribution system operator in case
settings have to be defined and/or provided, even when these settings are to be defined and/or
provided by another actor according to national and European legal framework.
NOTE 1 This includes European network codes and their national implementation, as well as further national
regulations.
NOTE 2 Further national requirements especially for the connection to the distribution network and the
operation of the generating plant can apply.
The requirements of this Technical Specification apply to all generating plants, electrical machinery
and electronic equipment, irrespective of the kind of primary energy source and irrespective of the
presence of loads in the producer’s network that meet all of the following conditions:
– converting any primary energy source into AC electricity;
– connected to a LV distribution network and rated at more than 16 A per phase;
– intended to operate in parallel with this distribution network under normal network operating
conditions.
NOTE 3 Generating plants rated up to and including 16 A per phase are covered by EN 50438.
NOTE 4 Generating plants connected to a MV distribution network fall into the scope of CLC/TS 50549-2.
Unless stated differently by the DSO generating plants connected to a medium voltage distribution
network with a maximum apparent power up to 100 kVA can comply with this Technical Specification
as alternative to the requirements of CLC/TS 50549-2. A different threshold may be defined by the
DSO.
This Technical Specification defines connection requirements.
This Technical Specification recognizes the existence of National Standards, Network Codes, and
specific technical requirements of the DSOs. These should be complied with.
Excluded from the scope are:
– the selection and evaluation of the point of connection;
– power system impact assessment;
– connection assessment;
– island operation of generating plants, both intentional and unintentional, where no part of the
distribution network is involved;
– active front ends of drives feeding energy back into the distribution network for short duration;
– requirements for the safety of personnel as they are already adequately covered by existing
European Standards.

Anforderungen für zum Parallelbetrieb mit einem Verteilnetz vorgesehene Erzeugungsanlagen – Teil 1: Anschluss an das Niederspannungsverteilnetz über 16 A je Phase

Diese Technische Spezifikation legt die technischen Anforderungen für den Anschluss von Erzeugungsan-lagen fest, die parallel mit einem öffentlichen Verteilungsnetz betrieben werden können. Diese Technischen Spezifikation soll als Referenz in einer Anschlussgenehmigung herangezogen werden, die zwischen einem VNB und einem Erzeuger getroffen wird. Die Anforderungen dieser Technischen Spezifikation beschränken sich auf den elektrischen Teil der Anlage, unabhängig von der verwendeten Primärenergiequelle. Diese Technischen Spezifikation gilt für alle dreiphasigen Erzeugungseinheiten, welche die folgenden Bedin-gungen – entweder als Einzelanlage oder als Gruppe von mehreren Anlagen mit einem gemeinsamen An-schlusspunkt – erfüllen: • Umwandlung einer beliebigen Primärenergie in Wechselstrom; • Bemessungsströme größer 16 A je Phase und Anschluss an ein Niederspannungsnetz; • Anlagen, die unter normalen Netzbetriebsbedingungen ständig parallel mit einem öffentlichen Ver-teilungs¬netz betrieben werden sollen; ANMERKUNG Erzeugungsanlagen bis 16 A je Phase werden durch die EN 50438 abgedeckt. Diese Technischen Spezifikation legt die Anschlussbedingungen und ein Verfahren für die Konformitäts¬prü-fung fest. Der Inselnetzbetrieb von Erzeugungsanlagen – beabsichtigt oder unbeabsichtigt – bei dem kein Teil des öffentlichen Verteilungsnetzes betroffen ist, liegt nicht im Anwendungsbereich dieser Technischen Spezifika-tion. Die Personensicherheit liegt nicht im Anwendungsbereich dieser Technischen Spezifikation. Diese Norm anerkennt die Existenz von nationalen Normen und Grid Codes: diese müssen eingehalten wer-den. Nur wenn keine nationalen Normen und Grid Codes vorhanden sind, sollen die Anforderungen dieser Technischen Spezifikation zur Anwendung kommen.

Prescriptions pour le raccordement de générateurs de plus de 16A par phase - Partie 1: Connexion au réseau de distribution BT

L'objet de la présente Spécification Technique est de fournir des instructions techniques pour le raccordement des centrales de production pouvant fonctionner en parallèle avec un réseau de distribution public. La présente Spécification Technique est destinée à être utilisée comme référence technique dans les contrats de raccordement entre les GRD et les producteurs d'électricité. Les exigences contenues dans la présente Spécification Technique s'appliquent uniquement aux machines et au matériel, quelle que soit la source d'énergie primaire. La présente Spécification Technique s'applique à toutes les unités de production triphasées qui satisfont à toutes les conditions qui suivent en tant qu'unité de production individuelle ou en tant que groupe d'unités de production ayant un point de raccordement commun: • convertissant toute source d'énergie primaire en électricité en courant alternatif; • est raccordé(e) au réseau BT et assigné(e) à plus de 16 A par phase; • est destiné(e) à fonctionner en parallèle avec un réseau de distribution public dans des conditions de fonctionnement normales. NOTE Les générateurs assignés à 16 A inclus par phase sont couverts par la norme EN 50438. La présente Spécification Technique définit les exigences applicables aux interconnexions ainsi qu'une procédure d'essai de conformité. Le fonctionnement en îlotage de centrales de production, qu'il soit intentionnel ou non, dans lequel aucune partie du système de distribution public n'est impliquée, est en dehors du domaine d'application de la présente Spécification Technique. La sécurité du personnel est en dehors du domaine d'application de la présente Spécification Technique. La présente Spécification Technique reconnaît l'existence de normes et de codes nationaux applicables aux réseaux: ceux-ci doivent être respectés. Il convient que les exigences de la présente Spécification Technique s'appliquent uniquement en l'absence de ces normes et codes nationaux.

Zahteve za priklop generatorjev za toke nad 16 A na fazo – 1. del: Priklop na nizkonapetostni distribucijski sistem

Namen te tehnične specifikacije je zagotoviti tehnična navodila o zahtevah za generatorje, ki jih je mogoče upravljati hkrati z razdelilnim omrežjem.
Zaradi praktičnih razlogov se ta tehnična specifikacija nanaša na upravljavca razdelilnega omrežja,
kadar je treba nastavitve opredeliti in/ali zagotoviti, tudi kadar mora te nastavitve opredeliti in/ali zagotoviti drug udeleženec v skladu z nacionalnim in evropskim pravnim okvirom.
OPOMBA 1: To zajema evropske omrežne kodekse in njihovo nacionalno izvajanje ter tudi dodatne nacionalne predpise.
OPOMBA 2: Uporabiti je mogoče dodatne nacionalne zahteve, zlasti za povezavo z razdelilnim omrežjem in delovanjem generatorja.
Zahteve iz tega tehničnega standarda se uporabljajo za vse generatorje, električne stroje in elektronsko opremo, ne glede na vrsto vira primarne energije in ne glede na prisotnost obremenitev v omrežju proizvajalca, ki izpolnjujejo naslednje pogoje:
– pretvarjanje katerega koli vira primarne energije v izmenični tok;
– povezava z nizkonapetnostnim razdelilnim omrežjem z nazivno vrednostjo več kot 16 A na fazo;
– namenjeni so za uporabo skupaj s tem razdelilnim omrežjem v običajnih pogojih delovanja
omrežja.
OPOMBA 3: Generatorji z nazivno vrednostjo do vključno 16 A na fazo so zajeti v standardu EN 50438.
OPOMBA 4: Generatorji, povezani s srednjenapetostnim omrežjem, so zajeti v področju uporabe standarda CLC/TS 50549-2.
Razen če upravljavec razdelilnega omrežja navede drugače, je mogoče, da so generatorji, povezani v srednjenapetostno razdelilno
omrežje z največjo navidezno močjo do 100 kVA, skladni s to tehnično specifikacijo kot alternativo zahtevam iz CLC/TS 50549-2. Upravljavec razdelilnega omrežja lahko opredeli drugačen prag.
Ta tehnična specifikacija določa zahteve za priključitev.
V tej tehnični specifikaciji se upošteva obstoj nacionalnih standardov, omrežnih kodeksov in
posebnih tehničnih zahtev upravljavcev razdelilnih omrežij. Te zahteve naj bi se upoštevale.
Ta standard ne zajema:
– izbire in ocene točke povezave;
– ocene učinka napajalnega sistema;
– ocene povezave;
– ločenega delovanja generatorjev, namernega in nenamernega, kadar ni vključen noben del
razdelilnega omrežja;
– aktivnih sprednjih delov pogonov, ki energijo za kratek čas usmerjajo nazaj v razdelilno omrežje;
– zahtev za varnost osebja, ker so že ustrezno zajete v veljavnih evropskih standardih.

General Information

• Status: Withdrawn
• Public Enquiry End Date: 17-Jun-2010
• Publication Date: 15-Mar-2015
• Withdrawal Date: 24-Jan-2022
• ICS: 29.160.20 - Generators
• ICS: 29.240.01 - Power transmission and distribution networks in general
• Technical Committee: NTF - Electricity energy supply systems
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 24-Jan-2022
• Due Date: 16-Feb-2022
• Completion Date: 25-Jan-2022
• Ref Project: CLC/TS 50549-1:2015 - Requirements for generating plants to be connected in parallel with distribution networks - Part 1: Connection to a LV distribution network above 16 A

RELATIONS

• Replaced By: SIST EN 50549-1:2019 - Requirements for generating plants to be connected in parallel with distribution networks - Part 1: Connection to a LV distribution network - Generating plants up to and including Type B
• Effective Date: 01-Apr-2019

Standards Content (sample)

SLOVENSKI STANDARD
SIST-TS CLC/TS 50549-1:2015
01-april-2015
Zahteve za priklop generatorjev za toke nad 16 A na fazo – 1. del: Priklop na
nizkonapetostni distribucijski sistem
Requirements for the connection of generators above 16 A per phase - Part 1:
Connection to the LV distribution system

Prescriptions pour le raccordement de générateurs de plus de 16A par phase - Partie 1:

Connexion au réseau de distribution BT
Ta slovenski standard je istoveten z: CLC/TS 50549-1:2015
ICS:
29.160.20 Generatorji Generators
29.240.01 2PUHåMD]DSUHQRVLQ Power transmission and
GLVWULEXFLMRHOHNWULþQHHQHUJLMH distribution networks in
QDVSORãQR general
SIST-TS CLC/TS 50549-1:2015 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CLC/TS 50549-1:2015
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SIST-TS CLC/TS 50549-1:2015
TECHNICAL SPECIFICATION CLC/TS 50549-1
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
January 2015
ICS 29.160.20
English Version
Requirements for generating plants to be connected in parallel
with distribution networks - Part 1: Connection to a LV
distribution network above 16 A

Prescriptions relatives au raccordement de générateurs de Anforderungen für den Anschluss von

plus de 16A par phase - Partie 1: Connexion au réseau de Stromerzeugungsanlagen über 16 A je Phase - Teil 1:

distribution BT Anschluss an das Mittelspannungsverteilungsnetz
This Technical Specification was approved by CENELEC on 2014-09-15.

CENELEC members are required to announce the existence of this TS in the same way as for an EN and to make the TS available promptly

at national level in an appropriate form. It is permissible to keep conflicting national standards in force.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. CLC/TS 50549-1:2015 E
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Contents Page

Foreword...................................................................................................................................................3

1 Scope ................................................................................................................................................4

2 Normative references ........................................................................................................................4

3 Terms and definitions ........................................................................................................................5

4 Requirements on generating plants ............................................................................................... 13

4.1 General ................................................................................................................................ 13

4.2 Connection scheme ............................................................................................................. 14

4.3 Choice of switchgear ............................................................................................................ 14

4.4 Normal operating range ....................................................................................................... 15

4.5 Immunity to disturbances ..................................................................................................... 17

4.6 Active response to frequency deviation ............................................................................... 19

4.7 Power response to voltage variations and voltage changes ............................................... 20

4.8 EMC and power quality ........................................................................................................ 25

4.9 Interface protection .............................................................................................................. 25

4.10 Connection and starting to generate electrical power .......................................................... 30

4.11 Active power reduction on set point ..................................................................................... 31

4.12 Requirements regarding single fault tolerance of interface protection system and

interface switch .................................................................................................................... 31

5 Conformance test procedure .......................................................................................................... 31

Annex A (informative) Interconnection requirements .......................................................................... 32

A.1 General ........................................................................................................................................... 32

A.2 Network integration ........................................................................................................................ 32

A.3 Clusters of single-phase generating units ...................................................................................... 33

Annex B (informative) Loss of Mains and overall power system security ............................................ 34

Annex C (informative) Examples of protection strategies .................................................................... 35

C.1 Introduction ..................................................................................................................................... 35

C.2 Example strategy 1 ......................................................................................................................... 36

C.3 Example strategy 2 ......................................................................................................................... 40

Annex D (normative) Abbreviations ...................................................................................................... 42

Bibliography ........................................................................................................................................... 43

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Foreword

This document (CLC/TS 50549-1:2015) has been prepared by CLC/TC 8X "System aspects of

electrical energy supply".

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such

patent rights.

This Technical Specification relates to both future European Network Codes and current technical

market needs. Its purpose is to give detailed description of functions to be implemented in products.

This Technical Specification is also intended to serve as a technical reference for the definition of

national requirements where European Network Codes requirements allow flexible implementation.

The stated requirements are solely technical requirements; economic issues regarding, e.g. the

bearing of cost are not in the scope of this document.

CLC/TC 8X plans future standardization work in order to ensure the compatibility of this Technical

Specification with the evolution of the legal framework.
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1 Scope

The purpose of this Technical Specification is to provide technical guidance on the requirements for

generating plants which can be operated in parallel with a distribution network.

For practical reasons, this Technical Specification refers to the distribution system operator in case

settings have to be defined and/or provided, even when these settings are to be defined and/or

provided by another actor according to national and European legal framework.

NOTE 1 This includes European network codes and their national implementation, as well as further national

regulations.

NOTE 2 Further national requirements especially for the connection to the distribution network and the

operation of the generating plant can apply.

The requirements of this Technical Specification apply to all generating plants, electrical machinery

and electronic equipment, irrespective of the kind of primary energy source and irrespective of the

presence of loads in the producer’s network that meet all of the following conditions:

– converting any primary energy source into AC electricity;
– connected to a LV distribution network and rated at more than 16 A per phase;

– intended to operate in parallel with this distribution network under normal network operating

conditions.

NOTE 3 Generating plants rated up to and including 16 A per phase are covered by EN 50438.

NOTE 4 Generating plants connected to a MV distribution network fall into the scope of CLC/TS 50549-2.

Unless stated differently by the DSO generating plants connected to a medium voltage distribution

network with a maximum apparent power up to 100 kVA can comply with this Technical Specification

as alternative to the requirements of CLC/TS 50549-2. A different threshold may be defined by the

DSO.
This Technical Specification defines connection requirements.

This Technical Specification recognizes the existence of National Standards, Network Codes, and

specific technical requirements of the DSOs. These should be complied with.
Excluded from the scope are:
– the selection and evaluation of the point of connection;
– power system impact assessment;
– connection assessment;

– island operation of generating plants, both intentional and unintentional, where no part of the

distribution network is involved;

– active front ends of drives feeding energy back into the distribution network for short duration;

– requirements for the safety of personnel as they are already adequately covered by existing

European Standards.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

EN 60255-127, Measuring relays and protection equipment  Part 127: Functional requirements for

over/under voltage protection (IEC 60255-127)

EN 61000-4-30, Electromagnetic compatibility (EMC)  Part 4-30: Testing and measurement

techniques  Power quality measurement methods (IEC 61000-4-30)
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 Part 1: Fundamental principles, assessment of
HD 60364-1, Low-voltage electrical installations
general characteristics, definitions (IEC 60364-1)

HD 60364-5-551, Low-voltage electrical installations  Part 5-55: Selection and erection of electrical

equipment  Other equipment  Clause 551: Low-voltage generating sets (IEC 60364-5-551)

IEC 60050, International Electrotechnical Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050 and the following

apply.
3.1
active factor

for a two-terminal element or a two-terminal circuit under sinusoidal conditions, ratio of the active

power to the apparent power

Note 1 to entry: In a three phase system, this is referring to the positive sequence component of the

fundamental.

Note 2 to entry: The active factor is equal to the cosine of the displacement angle.

[SOURCE: IEV 131-11-48, modified]
3.2
basic insulation
insulation of hazardous-live-parts which provides basic protection

Note 1 to entry: This concept does not apply to insulation used exclusively for functional purposes.

[SOURCE: IEV 195-06-06]
3.3
basic protection
protection against electric shock under fault-free conditions
[SOURCE: IEV 195-06-01]
3.4
cogeneration
combined heat and power (CHP)

combined generation of electricity and heat by an energy conversion system and the concurrent use of

the electric and thermal energy from the conversion system
3.5
converter connected generating technology

technology where a generating unit is connected to a distribution grid through a converter including

doubly fed induction machine based technology (DFIG)
3.6
design active power

maximum AC active power output at an active factor of 0,9 or the active factor specified by the DSO

for a certain generating plant or generating technology
3.7
directly coupled generating technology

technology where a generating unit is connected to a distribution grid without any converter

3.8
disconnection

separation of the active parts of the main circuit of the generating plant or unit from the network with

mechanical contacts providing at least the equivalent of basic insulation
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Note 1 to entry: Passive components like filters, auxiliary power supply to the generating unit and sense lines

can remain connected.

Note 2 to entry: For the design of basic insulation all voltage sources should be considered.

3.9
displacement angle

under sinusoidal conditions, phase difference between the voltage applied to a linear two-terminal

element or two-terminal circuit and the electric current in the element or circuit

Note 1 to entry: In a three phase system, this is referring to the positive sequence component of the

fundamental.
Note 2 to entry: The cosine of the displacement angle is the active factor.
3.10
distribution network

electrical network, including closed distribution networks, for the distribution of electrical power from

and to third parties connected to it, to and from a transmission or another distribution network, for

which a DSO is responsible
3.11
distribution system operator
DSO

natural or legal person responsible for the distribution of electrical power to the public and for

operating, ensuring the maintenance of and, if necessary, developing the distribution network in a

given area

Note 1 to entry: In some countries, the distribution network operator (DNO) fulfils the role of the DSO.

3.12
downstream

direction in which the active power would flow if no generating units, connected to the distribution

network, were running
3.13
droop

ratio of the per-unit change in frequency (Δf)/f (where f is the nominal frequency) to the per-unit

n n

change in power (ΔP)/ P (where P is the reference power at the instance when the frequency

ref ref
reaches a frequency threshold):
s= - (Δf/f ) / (ΔP/P )
n ref
[SOURCE: EV 603-04-08]
3.14
fundamental components of a three-phase system
3.14.1
phasor

representation of a sinusoidal integral quantity by a complex quantity whose argument is equal to the

initial phase and whose modulus is equal to the root-mean-square value

Note 1 to entry: For a quantity a(t) = A √2 cos(ωt +Ө ) the phasor is A exp jӨ .

0 0

Note 2 to entry: The similar representation with the modulus equal to the amplitude is called "amplitude phasor".

Note 3 to entry: A phasor can also be represented graphically.
[SOURCE: IEV 131-11-26, modified]
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3.14.2
positive sequence component of the fundamental

for a three-phase system with phases L1, L2 and L3, the symmetrical sinusoidal three-phase set of

voltages or currents having frequency equal to the fundamental frequency and which is defined by the

following complex mathematical expression:
X = (X + aX + a X )
1 L1 L2 L3
j2π/3

where a = e is the 120 degree operator, and X , X and X are the complex expressions of the

L1 L2 L3

fundamental frequency phase quantities concerned, that is, current or voltage phasors

Note 1 to entry: In a balanced harmonic-free system, only positive sequence component of the fundamental

π π
jθ j(θ+4 /3) j(θ+2 /3)

exists. For example, if phase voltage phasors are symmetrical U = Ue , U = Ue and U = Ue then

L1 L2 L3
π π π π
jθ j2 /3 j(θ+4 /3) j4 /3 j(θ+2 /3) jθ jθ jθ jθ
U = (Ue + e Ue + e Ue )/3 = (Ue + Ue + Ue )/3 = Ue .
[SOURCE: IEV 448-11-27]
3.14.3
negative sequence component of the fundamental

for a three-phase system with phases L1, L2 and L3, the symmetrical sinusoidal three-phase set of

voltages or currents having frequency equal to the fundamental frequency and which is defined by the

following complex mathematical expression:
X = (X + a X + aX )
2 L1 L2 L3
j2π/3

where a = e is the 120° operator, and X , X and X are the complex expressions of the

L1 L2 L3

fundamental frequency phase quantities concerned, that is, current or voltage phasors

Note 1 to entry: Negative sequence voltage or current components may be significant only when the voltages or

currents, respectively, are unbalanced. For example, if phase voltage phasors are symmetrical U = Ue , U =

L1 L2
π π π π π
j(θ+4 /3) j(θ+2 /3) jθ j4 /3 j(θ+4 /3) j2 /3
Ue and U = Ue then the negative sequence component U = (Ue + e Ue + e
L3 2
π π π
j(θ+2 /3) jθ j2 /3 j4 /3
Ue )/3 = Ue (1 + e + e )/3 = 0.
[SOURCE: IEV 448-11-28]
3.14.4
zero sequence component of the fundamental

for a three-phase system with phases L1, L2 and L3, the in-phase sinusoidal voltage or current

component having the fundamental frequency and equal amplitude in each of the phases and which is

defined by the following complex mathematical expression:
X = (X +X +X )
0 L1 L2 L3

where X , X and X are the complex expressions of the fundamental frequency phase quantities

L1 L2 L3
concerned, that is, current or voltage phasors
[SOURCE: IEV 448-11-29]
3.15
generating plant

sum of generating units connected at one point of connection, including auxiliaries and all connection

equipment

Note 1 to entry: This definition is intended to be used for verification of compliance to the technical requirements

of this standard. It may be different to the legal definition of a plant.
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3.16
generating plant controller

intelligence which ensures the fulfillment of performance requirements at the point of connection

(POC) towards a generating plant, usually by utilizing external measurement signals from the POC to

generate reference to a sub structure e.g. the generating units
3.17
generating unit

smallest set of installations which can generate electrical energy running independently and which can

feed this energy into a distribution network

Note 1 to entry: For example, a combined cycle gas turbine (CCGT) or an organic rankine cycle (ORC) after a

combustion engine is considered as a single generating unit.

Note 2 to entry: If a generating unit is a combination of technologies leading to different requirements, this has to

be settled case by case.

Note 3 to entry: A storage device operating in electricity generation mode and AC connected to the distribution

network is considered to be a generating unit.
3.18
interface protection relay

combination of different protection relay functions which opens the interface switch of a generating unit

and prevents its closure, whichever is appropriate in case of:
• a fault on the distribution network (with reference to POC voltage level);
• an islanding situation;

• the presence of voltage and frequency values outside the corresponding regulation values

3.19
interface protection system
a protection system that acts on the interface switch
3.20 Interface protection system timing
3.20.1
energizing quantity

energizing quantity by which the protection function is activated when it is applied under specified

conditions
Note 1 to entry: See also Figure 1.
[SOURCE: IEV 442-05-58, modified]
3.20.2
start time

duration of the time interval between the instant when the energizing quantity of the measuring relay in

reset condition is changed, under specified conditions, and the instant when the start signal asserts

Note 1 to entry: See also Figure 1.
[SOURCE: (EN 60255-151, modified]
3.20.3
time delay setting
intentional delay that might be adjustable by the user
Note 1 to entry: See also Figure 1.
3.20.4
operate time

duration of the time interval between the instant when the energizing quantity of a measuring relay in

reset condition is changed, under specified conditions, and the instant when the relay operates

Note 1 to entry: See also Figure 1.
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Note 2 to entry: Operate time is start time plus time delay setting.
[SOURCE: IEV 447-05-05, modified]
3.20.5
disconnection time

sum of operate time of the protection system and the opening time of the interface switch

Note 1 to entry: See also Figure 1 where the CB opening time indicates the opening time.

3.20.6
reset time

duration of the time interval between the instant when the energizing quantity of a measuring relay in

operate condition is changed, under specified conditions, and the instant when the relay resets

Note 1 to entry: See also Figure 1.
[SOURCE: IEV 447-05-06 modified]
3.20.7
disengaging time

duration of the time interval between the instant a specified change is made in the value of the input

energizing quantity which will cause the relay to disengage and instant it disengages

Note 1 to entry: See also Figure 1.
[SOURCE: IEV 447-05-10]
Figure 1  Main times defining the interface protection performance
3.21
islanding

situation where a section of the distribution network, containing generation, becomes physically

disconnected from the rest of distribution network and one or more generating units maintain a supply

of electrical energy to the isolated section of the distribution network
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3.22
low voltage (LV) distribution network

electric distribution network with a voltage whose nominal r.m.s. value is U ≤ 1 kV

3.23
maximum active power
max

maximum AC active power output that the generating unit or the sum of all the generating units in a

generating plant is designed to achieve under normal operating conditions

Note 1 to entry: This maximum power is defined by a measurement with 10 min averaging.

3.24
maximum apparent power
max

maximum AC apparent power output that the generating unit or the sum of all the generating units in a

generating plant is designed to achieve under normal operating conditions

Note 1 to entry: This maximum power is defined by a measurement with 10 min averaging.

3.25
momentary active power
the actual AC active power output at a certain instant
3.26
nominal frequency
frequency used to designate and identify equipment or a power system

Note 1 to entry: For the purpose of this standard, the nominal frequency f is 50 Hz.

[SOURCE: IEV 151-16-09, modified]
3.27
nominal voltage

voltage by which a supply network is designated or identified and to which certain operating

characteristics are referred
3.28
observation time

time during which all the voltage and the frequency values are observed to be within a specified range

prior to a generating plant connection to the distribution network or start to generate electric power

3.29
operation in parallel with the distribution network

situation where the generating plant is connected to a distribution network and operating

3.30
point of connection
POC

reference point on the electric power system where the user’s electrical facility is connected

Note 1 to entry: For the purpose of this standard, the electric power system is the distribution network.

[SOURCE: IEV 617-04-01]
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3.31
power factor

under periodic conditions, ratio of the absolute value of the active power P to the apparent power S:

|𝑃|
𝜆 =

Note 1 to entry: Under sinusoidal conditions, the power factor is the absolute value of the active factor.

[SOURCE: IEV 131-11-46]
3.32
power system stability

the capability of a power system to regain a steady state, characterized by the synchronous operation

of the generating plants after a disturbance
[SOURCE: IEV 603-03-01]
3.33
primary energy source
non-electric energy source supplying an electric generating unit

Note 1 to entry: Examples of primary energy sources include natural gas, wind and solar energy. These sources

can be utilized, e.g. by gas turbines, wind turbines and photovoltaic cells.
3.34
producer

party who already has or is planning to connect an electricity generating plant to a distribution network

3.35
producer’s network

electrical installations downstream from the point of connection owned/operated by the producer for

internal distribution of electricity
3.36
protection relay

measuring relay which detects faults or other abnormal conditions in a power system or of a power

equipment

Note 1 to entry: A protection relay is a component part of a protection system.

Note 2 to entry: An interface protection relay is a protection relay acting on the interface switch.

[SOURCE: IEV 447-01-14]
3.37
protection system

an arrangement of one or more protection equipments, and other devices intended to perform one or

more specified protection functions

Note 1 to entry: A protection system includes one or more protection equipments, instrument transformer(s),

wiring, tripping circuit(s), auxiliary supply(s) and, where provided, communication system(s). Depending upon the

principle(s) of the protection system, it may include one end or all ends of the protected section and, possibly,

automatic reclosing equipment.
Note 2 to entry: The circuit-breaker(s) are excluded.
[SOURCE: IEV 448-11-03]
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3.38
rated current

maximum continuous AC output current which a generating unit or generating plant is designed to

achieve under normal operating conditions
[SOURCE: 415-04-03, modified]
3.39
reference voltage

value specified as the base on which residual voltage, thresholds and other values are expressed in

per unit or percentage terms

Note 1 to entry: For the purpose of this standard, the reference voltage is the nominal voltage or the declared

voltage of the distribution network.
[SOURCE: EN 50160, 3.18, modified]
3.40
single fault tolerance

built-in capability of a system to provide continued correct execution of its function in the presence of a

single fault
[SOURCE: IEV 394-33-13, modified]
3.41
switch
device for changing the electric connections among its terminals
[SOURCE: IEV 151-12-22]
Figure 2  Electricity generating plant connected to a distribution network
(schematic view of switches)
3.41.1
main switch

switch installed as close as possible to the point of connection, for protection against internal faults

and disconnection of the whole plant from the distribution network
Note 1 to entry: See also Figure 2.
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3.41.2
interface switch

switch (circuit breaker, switch or contactor) installed in the producer’s network, for separating the

part(s) of the producer’s network containing at least one generation unit from the distribution network

Note 1 to entry: See also Figure 2.

Note 2 to entry: In some situations, the interface switch may be used to enable island operation of part of the

producer’s network, if technically feasible.
3.41.3
generating unit switch

switch installed electrically close to the terminals of each generating unit of the generating plant, for

protection and disconnection of that generating unit
Note 1 to entry: See also Figure 2.
3.42
temporary operation in parallel with the distribution network

conditions in which the generating plant is connected to a distribution network, during defined short

periods, to maintain the continuity of the supply voltage and to facilitate testing

3.43
transmission system operator
TSO

natural or legal person responsible for operating, ensuring the maintenance of and, if necessary,

developing the transmission system in a given area and, where applicable, its interconnections with

other power systems, and for ensuring the long-term ability of the power system to meet reasonable

demands for the transmission of electricity
3.44
voltage control system

automatic control system of a generating unit or generating plant which counteracts network voltage

changes, for instance but not only, by adjusting reactive power output accordingly

3.45
...