SIST-TS CLC/TS 50549-2:2015

SLOVENSKI STANDARD
SIST-TS CLC/TS 50549-2:2015
01-april-2015
Zahteve za priklop generatorjev za toke nad 16 A na fazo - 2. del: Priklop na
srednjenapetostni distribucijski sistem
Requirements for the connection of generators above 16 A per phase - Part 2:
Connection to the MV distribution system
Prescriptions relatives au raccordement de générateurs de plus de 16A par phase -
Partie 2: Connexion au réseau de distribution MT
Ta slovenski standard je istoveten z: CLC/TS 50549-2:2015
ICS:
29.160.20 Generatorji Generators
29.240.01 2PUHåMD]DSUHQRVLQ Power transmission and
GLVWULEXFLMRHOHNWULþQHHQHUJLMH distribution networks in
QDVSORãQR general
SIST-TS CLC/TS 50549-2:2015 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CLC/TS 50549-2:2015

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SIST-TS CLC/TS 50549-2:2015

TECHNICAL SPECIFICATION CLC/TS 50549-2

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 2: Connection to a MV
distribution network
Prescriptions relatives au raccordement de générateurs de Anforderungen für den Anschluss von
plus de 16A par phase - Partie 2: Connexion au réseau de Stromerzeugungsanlagen über 16 A je Phase - Teil 2:
distribution MT 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 50549-2:2015 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 . 15
4.1 General . 15
4.2 Connection scheme . 16
4.3 Choice of switchgear . 16
4.4 Normal operating range . 16
4.5 Immunity to disturbances . 18
4.6 Active response to frequency deviation . 21
4.7 Power response to voltage variations and voltage changes . 23
4.8 EMC and power quality . 29
4.9 Interface protection . 30
4.10 Connection and starting to generate electrical power . 35
4.11 Active power reduction on set point . 36
4.12 Remote information exchange . 37
5 Conformance test procedure . 37
Annex A (informative)  Interconnection requirements . 38
Annex B (informative) Remote information exchange . 40
Annex C (informative) Frequency stabilizing services . 46
C.1 General . 46
C.2 Frequency sensitive mode . 46
C.3 Power system stabilization . 47
C.4 Synthetic inertia . 47
Annex D (informative) Loss of Mains and overall power system security . 48
Annex E (informative) Examples of protection strategies . 49
E.1 Introduction . 49
E.1.1 General . 49
E.2 Example strategy 1 . 50
E.3 Example strategy 2 . 54
Annex F (normative) Abbreviations . 56
Bibliography . 57

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Foreword
This document (CLC/TS 50549-2:2015) 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 MV distribution network;
– intended to operate in parallel with this distribution network under normal network operating
conditions.
NOTE 3 Generating plants connected to a LV distribution network fall into the scope of EN 50438 (up to 16 A)
and CLC/TS 50549-1 (above 16 A).
Unless stated differently by the DSO, a generating plant with a maximum apparent power up to 100
kVA can, as alternative to the requirements of this Technical Specification, comply with
CLC/TS 50549-1. 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 60044-2, Instrument transformers  Part 2: Inductive voltage transformers (IEC 60044-2)
EN 60044-7, Instrument transformers  Part 7: Electronic voltage transformers (IEC 60044-7)

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 Part 127: Functional requirements for
EN 60255-127, Measuring relays and protection equipment
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)
EN 61869-3, Instrument transformers  Part 3: Additional requirements for inductive voltage
transformers (IEC 61869-3)
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 131-11-49, modified]
3.2
available active power
P
A
maximum AC active power available from the prime mover subject to the availability and magnitude of
the primary energy source at the relevant time
Note 1 to entry:  The maximum active power considers all constraints regarding e.g. the primary energy source or
the availability of a heat sink for CHP.
3.3
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]
3.4
basic protection
protection against electric shock under fault-free conditions
[SOURCE: IEV 195-06-01]
3.5
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
3.6
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)

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3.7
declared supply voltage
U
c
supply voltage U agreed by the power system operator and the network user
c
Note 1 to entry:  Generally declared supply voltage U is the nominal voltage U but it may be different according
c n
to the agreement between the power system operator and the network user.
[SOURCE: EN 50160]
3.8
design active power
P
D
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
3.9
directly coupled generating technology
technology where a generating unit is connected to a distribution grid without any converter
Note 1 to entry:  Soft starters are not considered as converter in this definition.
3.10
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
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.
3.11
displacement angle
φ
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.
[SOURCE IEV 131-11-48 MOD]
3.12
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
3.13
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.
3.14
downstream
direction in which the active power would flow if no generating units, connected to the distribution
network, were running

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3.15
droop
the 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: IEV 603-04-08]
3.16
voltage dead band
amplitude of the voltage step ΔU within which a specific behaviour is not required
3.17
fundamental components of a three-phase system
3.17.1
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, MOD]
3.17.2
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:
1
2
X = (X +aX +a X )
1 L1 L2 L3
3
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
jθ j(θ+4 /3) j(θ+2 /3)
π π
exists. For example, if phase voltage phasors are symmetrical U = Ue , U = Ue and U = Ue then
L1 L2 L3
jθ j2π/3 j(θ+4π/3) j4π/3 j(θ+2π/3) jθ jθ jθ jθ
U = (Ue + e Ue + e Ue )/3 = (Ue + Ue + Ue )/3 = Ue
1
[SOURCE: IEV 448-11-27].
3.17.3
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:
1
2
X = (X +a X +aX )
2 L1 L2 L3
3
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:  Negative sequence voltage or current components may be significant only when the voltages or
jθ
currents, respectively, are unbalanced. For example, if phase voltage phasors are symmetrical U = Ue , U =
L1 L2

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j(θ+4 /3) j(θ+2 /3) jθ j4 /3 j(θ+4 /3) j2 /3 j(θ+2 /3)
π π π π π π
Ue and U = Ue then the negative sequence component U = (Ue + e Ue + e Ue )/3
L3 2
jθ j2 /3 j4 /3
π π
= Ue (1 + e + e )/3 = 0.
[SOURCE: IEV 448-11-28]
3.17.4
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:
1
X = (X +X +X )
0 L1 L2 L3
3
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]
3.18
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.
3.19
generating plant controller
functional controller 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
3.20
generating plant class threshold
power threshold to be defined by the DSO to discriminate between class I and class II generating
plants
Note 1 to entry:  This threshold is intended to allow for an easier connection process for smaller plants. Class I
generating plants may only be evaluated on generating unit level.
Note 2 to entry:  This threshold can be defined generally or case by case for specific generating plants.
3.21
generating plant of class I
generating plant with maximum power equal or below the generating plant class threshold
3.22
generating plant of class II
generating plant with maximum power above the generating plant class threshold
3.23
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.

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3.24
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
3.25
interface protection system
protection system that acts on the interface switch
3.26 Interface protection system timing
3.26.1
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]
3.26.2
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]
3.26.3
time delay setting
intentional delay that might be adjustable by the user
Note 1 to entry:  See also Figure 1.
3.26.4
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.
Note 2 to entry:  Operate time is start time plus time delay setting.
[SOURCE: IEV 447-05-05, modified]
3.26.5
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.
3.26.6
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]

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3.26.7
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
3.27
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
3.28
maximum active power
P
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.
3.29
maximum apparent power
S
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.

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3.30
medium voltage (MV) distribution network
electric distribution network with a voltage whose nominal r.m.s. value is 1 kV < U ≤ 36 kV
n
Note 1 to entry:  Because of existing network structures, the upper boundary of MV can be different in some
countries.
3.31
momentary active power
P
M
actual AC active power output at a certain instant
3.32
nominal frequency
f
n
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.
n
[SOURCE: IEV 151-16-09, modified]
3.33
nominal voltage
U
n
voltage by which a supply network is designated or identified and to which certain operating
characteristics are referred
3.34
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.
3.35
operation in parallel with the distribution network
situation where the generating plant is connected to a distribution network and operating
3.36
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 Technical Specification, the electric power system is the distribution
network.
[SOURCE: IEV 617-04-01 MOD]
3.37
power factor
under periodic conditions, ratio of the absolute value of the active power P to the apparent power S:

| |
𝑃
𝜆 =
𝑆
Note 1 to entry:  Under sinusoidal conditions, the power factor is the absolute value of the active factor.
[SOURCE: IEV 131-11-46]
3.38
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]

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3.39
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.
3.40
producer
party who already has or is planning to connect an electricity generating plant to a distribution network
3.41
producer’s network
electrical installations downstream from the point of connection owned/operated by the producer for
internal distribution of electricity
3.42
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]
3.43
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]
3.44
rated current
maximum continuous AC output current which a generating unit or generating plant is designed to
achieve under normal operating conditions
[SOURCE: IEV 415-04-03, modified]
3.45
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]
3.46
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]

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3.47
...