Grid Code Requirements for Wind EnergyFacilities Connected to Distribution or Transmission System in South Africa- Version 5_ 4

7/30/2019 Grid Code Requirements for Wind EnergyFacilities Connected to Distribution or Transmission System in South Afric

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GRID CODE REQUIREMENTS FOR WINDGRID CODE REQUIREMENTS FOR WINDGRID CODE REQUIREMENTS FOR WINDGRID CODE REQUIREMENTS FOR WINDENERGY FACILITIESENERGY FACILITIESENERGY FACILITIESENERGY FACILITIES CONNECTED TOCONNECTED TOCONNECTED TOCONNECTED TODISTRIBUTIONDISTRIBUTIONDISTRIBUTIONDISTRIBUTION OROROROR TRANSMISSIONTRANSMISSIONTRANSMISSIONTRANSMISSION

SYSTEMSSYSTEMSSYSTEMSSYSTEMS IN SOUTH AFRICAIN SOUTH AFRICAIN SOUTH AFRICAIN SOUTH AFRICA

Version 5.4July 2012


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Grid Code Requirements for Connecting WEFsin South Africa Rev. 5.4 July 2012

Issued by:

The RSA Grid Code SecretariatAttention: Mr. Target Mchunu / Mr. Bernard MagoroEskom Transmission DivisionP.O Box 103, Germiston 1400

Tell: +27 (0)11 871 3076 / 2774Fax: +27 (0)86 663 8418Email: [email protected] or [email protected]


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Content Page

1. Objective ................................................................................................. 4

2. Scope ....................................................................................................... 4

3. Definitions and Abbreviations ............................................................... 4

4. WEFConnection Requirements at the POC......................................... 7

4.1 Tolerance of Frequency and Voltage Deviations .................................... 74.1.1 Normal operating conditions .............................................................................. 74.1.2 Abnormal operating conditions .......................................................................... 9

4.2 Power Quality .......................................................................................... 124.3 Control and Monitoring functions .......................................................... 12

4.3.1 Frequency response control ............................................................................ 134.3.2 Reactive power and voltage control functions ................................................. 15

4.4 Reactive power control requirements ................................................... 184.5 Active Power Curtailment ....................................................................... 21

4.6 Ramp Rates ............................................................................................. 21

5. Provision of Data and Electrical Dynamic Simulation Models.......... 21

6. Signals, Communications & Control................................................... 23

6.1 Signals from the WEF to SO ................................................................... 236.1.1 Signals List #1 ................................................................................................. 236.1.2 Signals List #2 ................................................................................................. 246.1.3 Signals List #3 ................................................................................................. 246.1.4 Signals List #4 ................................................................................................. 246.1.5 Signals List #5 ................................................................................................. 24

6.2 Update Rates ........................................................................................... 256.3 Control Signals Sent from SO to the WEF ............................................. 25

6.3.3 Connection Point Circuit Breaker Trip facility .................................................. 25

6.4 MW Forecast ............................................................................................ 266.5 Data Communications Specifications ................................................... 26

7. Protection facilities ............................................................................... 26

8. Compliance Monitoring ........................................................................ 27

9. Reporting ............................................................................................... 27

APPENDIX A WEF COMPLIANCE TESTING ........................................... 28


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1. Objective

(1) The primary objective of this document is to specify grid connection conditions for wind

energy facilities (WEFs) connected to or seeking connection to the South African electricity

transmission system (TS) or the distribution system(DS). It sets out rules and obligations to

which participantsmust comply in order to connect WEFsto the TSor the DS.

(2) This document shall be used together with other applicable sections of the Grid Codeand

the Distribution Codeas compliance criteria applicable to WEFsin South Africa.

(3) WEFgeneratorsshall demonstrate compliance to the requirements of this document and

any other applicable codes or standard approved by NERSA before being allowed to connect

to the DSor the TSand operate commercially.

2. Scope

(1) The requirements in this document are applicable to a WEF connected or seeking

connection to the DS or TS in South Africa as well as the respective DS and TS network

service providers (NSPs).

(2) Any replacement of and/or major modification to an existing WEFshall also be required todemonstrate compliance to these requirement before commercial operation.

(3) Matters relating to wind energy procurement and applicable tariffs are excluded from this

document.

3. Definitions and Abbreviations

(1) Unless otherwise indicated, words and terminology in this document shall have the same

meaning as those in the RSA Grid Codeand Distribution Code. The following definitions and

abbreviations are used in this document.

Available Active Power

The amount of Active Power (MegaWatts) that the WEFcould produce based on current wind

conditions.

Curtailed Active Power


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The amount of Active Power that the WEF is permitted to generate by the SO or other

Network Operator subject to network or system constrains.

Distribution System (DS)

As defined in the RSA Grid Code, Preamble section

Droop

The ratio of the per unit steady state change in speed, or in frequency to the per unit steady

state change in power output.

Generator


High voltage (HV)

The set of nominal voltage levels greater than 33 KV and up to and including 220 kV.

High voltage ride through (HVRT)

Capability of the WEF to stay connected to the network following voltage peaks caused by

switching or disturbances on any or all phases in the TSor DS.

Low voltage (LV)

Nominal voltage levels from 0 up to 1 kV. [SANS 1019]

Low voltage ride through (LVRT)

Capability of the WEF to stay connected to the network following voltage dips caused by a

short-circuit or disturbances on any or all phases in the TSor DS.

Maximum Export Capacity (MEC)

The contracted highest active power (in MW), measured at the POC, which the WEF is

licensed to supply in accordance with the WEFgeneratorsconnection agreement.

Medium voltage (MV)

The set of nominal voltage levels greater than 1 kV and up to and including 33 kV.

Active Power Curtailment

The reduction of Active Power output from WEFin response to an instruction from the SO or

another Network Operator

MW Curtailment Set-point


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The limit set by the SOor another Network Operator for the amount of Active Power that the

WEF is permitted to generate. This instruction may be issued manual or automatically via a

tele-control facility.

National Energy Regulator of South Africa (NERSA)The legal entity established in terms of the National Energy Regulator Act, 2004 (Act 40 of

2004), as amended.

National Transmission Company (NTC)


Network Service Provider (NSP)

A legal entity that is licensed, by the NERSA to own, operate and maintain a network on the

TSor the DS

Point of Common Coupling (PCC)


Point of Connection (POC)


Power Quality

Characteristics of the electricity at a given point on an electrical system, evaluated against a

set of reference technical parameters. These characteristics include:

voltage quality, i.e. voltage regulation (magnitude), voltage harmonics, voltage flicker,

voltage unbalance;

voltage events, i.e. voltage dips, voltage swells, voltage transients;

(supply) interruptions;

frequency of supply.

System Operator (SO)


Transmission System (TS)


Voltage Quality

Subset of power quality referring to steady-state voltage quality, i.e. voltage regulation

(magnitude), voltage harmonics, voltage flicker, voltage unbalance. The current drawn from or

injected into the POC is the driving factor for voltage quality deviations.


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Wind Energy Facility (WEF)

A single wind turbine connected to the distribution or transmission system or a group of

several wind turbines with associated equipment with common connection(s) to the

distribution or transmission system.

WEF generator

The legal entity that establishes the WEFand requests a grid connection.

4. WEFConnection Requirements at the POC

(1) All wind turbine units within the WEFshall comply with the requirements of IEC Technical

Specification Series, TS 61400. However, provisions of this document and the RSA Grid

Codeand Distribution Codeshall take precedence whenever there is a conflict.

(2) The requirements outlined in this code are to be considered as minimum design

requirements.

4.1 Tolerance of Frequency and Voltage Deviations

(1) A WEF shall be able to withstand frequency and voltage deviations at the POC under

normal and abnormal operating conditions while reducing the active power as little as

possible.

(2) Normal operating conditions and abnormal operating conditions are described in section

4.1.1 and section 4.1.2, respectively.

4.1.1 Normal operating conditions

(1) The WEFshall be designed to be capable of operating within the voltage range of 10%

around the nominal voltage at the POC. The actual operating voltage differs from location to

location, and this shall be decided by the network service provider (NSP) in consultation with

affected customers(including the WEF generator), and implemented by the WEFgenerator.

(2) The WEFshall be designed to operate within the network frequency range of 47.00 Hz to

52.00 Hz, subject to clause (3) below.


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(3) The WEF, when in operation, shall be capable of operation for specific periods as a

function of system frequency in accordance with Figure 1 and Figure 2 below.

Figure 1: Minimum frequency operating range of a WEF (Cumulative over the life of the WEF)

Figure 2: Minimum frequency operating range of a WEF (during a system frequency disturbance)

(4) The WEFshall remain connected to the DSor TSduring rate of change of frequency of

values up to and including 0,5 Hz per second, provided the network frequency is still within

the continuous frequency characteristic.

46

47

48

49

50

51

52

0.1 1 10 100 1000

Duration of the incident, Seconds

200ms

Continuous

operating range

(49.0 Hz to 51.0 Hz)

60

Frequency,

Hz

64

MINIMUM OPERATING RANGE FOR WEFs

46

47

48

49

50

51

52

53

0.001 0.01 0.1 1 10 100 1000 10000

Time (Minutes)

200ms

ContinuousOperating range(49.0 Hz to 51.0Hz)

80min

SystemFrequency[Hz]

MINIMUM OPERATING RANGE FOR WEFsNominal[50 Hz]

H2

H1

L1

L2

L3

L4


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(5) Automatic connection of a WEF can at the earliest take place three seconds after the

voltage has come to lie within the normal operating voltage range and the frequency lies

within 47.00 and 52.00 Hz. The setting of the frequency limits is determined by the SOand

the NSPupon commissioning.

4.1.2 Abnormal operating conditions

(1) The WEFshall be designed to withstand voltage drops and peaks, as shown in Figure 3,

and supply and absorb reactive current as shown in Figure 4 without disconnecting or

reducing its output.

(2) The WEF shall be able to withstand voltage drops down to 0% of the voltage at the POC

over a period of minimum 0.150 s (line-to-line voltages for the 50 Hz component) without

disconnecting, as shown in Figure 3.

(3) At the POC a WEF shall be able to withstand voltage peaks up to 120% of nominal

voltage at the POC over a minimum period of 2seconds (line-to-line voltages for the 50 Hz

component) without disconnecting, as shown in Figure 3.

(4) Figure 3 shall apply to all types of faults (symmetrical as well as asymmetrical) and the

bold line shall represent the minimum voltage of all the phases.

Figure 3: Fault Ride Through Capability for the WEF

(5) The following requirements shall be complied with in the event of symmetrical as well as

asymmetrical faults, i.e. the requirements shall apply in case of faults in one, two or three

phases:


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Area A (Figure 3 and 4): The WEFshall stay connected to the network and uphold

normal production.

Area B (Figure 3 and 4): The WEFshall stay connected to the network. The WEF

shall provide maximum voltage support by supplying a controlled amount of reactive

current so as to ensure that the WEFhelps to stabilise the voltage, see Figure 4.

Area C (Figure 3): Disconnecting the WEFis allowed.

Area C (Figure 4): Once the voltage at the POC is below 20%, the WEF shall

continue to supply reactive current within its technical design limitations so as to

ensure that the WEFhelps to stabilise the voltage. Disconnection is only allowed after

the conditions of figure 3 have been fulfilled.

Area D (Figure 3 and 4): The WEFshall stay connected to the network. The WEF

shall provide maximum voltage support by absorbing a controlled amount of reactive

current so as to ensure that the WEFhelps to stabilise the voltage within the design

capability offered by the WEF, see Figure 4.

(6) If the voltage U reverts to area A during a fault sequence, subsequent voltage drops shall

be regarded as a new fault situation. If several successive fault sequences occur within area

B and evolve into area C, disconnection is allowed.

(7) In connection with symmetrical faults in area B, the WEF shall have a control function

capable of controlling the reactive current injection, according to Figure 4.


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AreaD

AreaA

Figure 4: Requirements for Reactive Power Support, IQ, during voltage drops or surges at the

POC

(8) Control shall follow Figure 4 so that the reactive current injection follows the control

characteristic with a tolerance of 20% after 100 milliseconds.

(9) The supply of reactive power has first priority in area B, while the supply of active powerhas second priority.

(10) If possible, active power shall be maintained during voltage drops, but a reduction in

active power within the WEF'sdesign specifications is acceptable.


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4.2 Power Quality

(1) An assessment of the impact of the WEF on power quality shall be done by the NSP

concerning the following disturbances at the POC:

voltage fluctuations:

a. rapid voltage changes

b. flicker

high-frequency currents and voltages:

a. harmonics

b. inter-harmonics

c. disturbances greater than 2 kHz.

unbalanced currents and voltages:

a. deviation in magnitude between three phases

b. deviation in angle separation from 120

between three phases. WEFwill generally follow the supply network frequency:

a. Any attempt by the WEFto change the supply frequency may result in severe

distortion of the voltage at the POC, PCCand other points in the network.

(2) Voltage regulation impact shall be monitored at the POC.

(3) Voltage and current quality distortion levels emitted by the WEF at the POC shall not

exceed the apportioned levels as supplied by the relevant distribution or transmission NSP.

(4) The calculation of these emission levels shall be based on internationally recognised and

acceptable practice (e.g. relevant parts of IEC 61000-series) and / or local industry practice

(as described in NRS 048-4). The allocation methodology shall be fair and transparent.

(5) The WEFgenerator shall ensure that the WEFis designed, configured and implemented

in such a way that the specified emission limit values are not exceeded.

(6) The maximum allowable voltage change at the POC after a switching operation

(compensation devices) by the WEFshall not be greater than 2%.

4.3 Control and Monitoring functions

(1) This section describes the design capability requirement of the WEF. The actual

operating mode and settings of the WEFshall be agreed between the WEF generatorand the

SO, NSPand / or the local network operator.

(2) All control functions mentioned in the following sections refer to the POC.


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(3) It shall be possible to activate/deactivate all the control functions and set them using

external signals, as described in section 6. The actual settings shall be agreed with the NSP

before the WEFcan be connected to the TSand DS.

(4) After a WEFhas been disconnected due to a fault in the TSand DS, the WEFshall beautomatically connected after three seconds after the voltage and the frequency have settled

within the limits stated in section 4.1. A WEF which has been disconnected by an external

signal prior to a fault occurring in the TSor DSshall not be connected until the external signal

has been eliminated, and the voltage and the frequency have once again come to lie within

the normal operational conditions limits stated in section 4.1.

4.3.1 Frequency response control

(1) The WEF shall remain connected to the DS or TS and all wind turbines shall remain

connected during rate of change of frequency of values up to and including 0,5 Hz per

second, provided the network frequency is still within the continuous frequency characteristic.

(2) The WEF shall include a Frequency Response System. The Frequency Response

Systemshall provide the response as illustrated in figure 5 below.

(3) The Frequency Response Systemshall be designed to be capable of regulating power

output as displayed in the Power-Frequency Response Curve.

Figure 5: Power-Frequency Control Curve


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(4) A frequencydead-band setting (B-C) capable of being set between 0 and 500mHz shall

be provided with each WEF. The actual setting to be implemented by the WEFshall be as

specified by the SOor in the RSAGrid Code.

(5) Under continuous operation frequency range as shown in figure 1, the WEF shall becapable of operating continuously at a power output level of 95% available active powerand

above. The actual operating point shall be agreed with the SO.

(6) If the frequency rises to a level above 50.15Hz, then the WEFshall act to ramp down the

WEFs active power output. The response rate of each available online WEF shall be a

minimum of 1% of WEFrated capacity per second (MW/second).

(7) When the frequency is below the normal range and is recovering back towards the

normal range, the Frequency Response System shall act to ramp down the WEF Active

Power output in accordance with the Frequency/Active Power characteristic defined by the

line A-B.

(8) Once the frequency rises to a level above point C, the Frequency Response System

shall act to ramp down the WEF Active Power output in accordance with the

Frequency/Active Power characteristic defined by the line C-D-E.

(9) Points A, B, C, D and E shall depend on a combination of the frequency, Active

Power and MW curtailment set-point settings. These settings may be different for each WEF

depending on system conditions and WEF location. These settings are defined in Table 2,

and expected to change according to system requirements.

Table 2: Frequency and % Available Active Power Settings for the Points A, B, C, D and E

Point Frequency Wind Energy Facility Power output

(% of available active power)

A FA PA

B FB Minimum of : PB orMW Curtailment set-point

(Converted to a % of Available active Power)

C FC Minimum of : PC or

MW Curtailment set-point


D FD Minimum of : PD or

MW Curtailment set-point


E FE PE = 0%


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(10) Settings for each of FA, FB, FC, FD, FE, PA, PB, PC, PD and PE shall be specified by

the SO. WEF shall be responsible for implementing the appropriate settings during

commissioning. Alterations to the MW Curtailment Set-pointshall be sent in real-time by the

SOand these alterations shall be implemented by the WEFwithin one minute of receipt of theappropriate signal or instruction from the SO(operational limits and feedback response to the

signal will be provided).

(11) Alterations to the WEF Active Poweroutput, triggered by frequency changes outside the

dead-band, shall be achieved by proportionately altering the Active Power output of all

available wind turbines as opposed to switching individual WEF on or off, in so far as

possible.

(12) No time delay other that those necessarily inherent in the design of the Frequency

Response System shall be introduced. The response rate of each available online wind

turbine shall be a minimum of 1% of wind turbine rated capacity per second (MW/second).

The frequency Response System shall continuously monitor the frequency in order to

continuously determine the WEF appropriate Active Power output by taking account of the

WEF Available Active Powerand Curtailed Active Power.

(13) If the frequency rises to a level above the line D-E, as defined by the Power-Frequency

Response Curve, SO recognises that WEFs may cease to generate. Any WEF which has

ceased generation shall be brought back on load provided both the frequency and voltage are

back to normal operating conditions for longer than 3 seconds.

(14) After a failure in the local network where the WEFexists, the WEFshall be returned to

service as soon as the conditions allow. Where manual reset of the WEF is required by the

WEFgenerator, this shall be achieved without undue delay.

(15) The SOshall give the WEF generator a minimum of 2 weeks written notice if changes to

any of the curves parameters (i.e. FA, FB, FC, FD, FE, PA, PB, PC, PD or PE) are required.

The WEF generator shall confirm in writing to the SO that requested changes have been

implemented within two weeks of receiving the SOsrequest.

4.3.2 Reactive power and voltage control functions

(1) A WEFshall be equipped with reactive power control functions capable of controlling the

reactive power supplied by a WEFat the POCas well as a voltage control function capable of

controlling the voltage at the POCvia orders using setpoints and gradients.


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(2) The WEF shall be equipped with the following reactive power and voltage control

functions. These functions are mutually exclusive, which means that only one of the three

functions can be activated at a time.

Q-control

Power Factorcontrol

Voltage-control

(3) The applied parameter settings for reactive power and voltage control functions shall be

determined before commissioning by the NSP in collaboration with the SO. Each of the

control functions shall be described in the following sub-sections.

4.3.2.1 Q - Control

(1) Q control is a control function controlling the reactive power independently of the active

power and the voltage at the POC. This control function is illustrated on Figure 6 as a vertical

line.

(2) If the Q control setpoint is to be changed, such change shall be commenced within two

seconds and completed not later than 30 seconds after receipt of an order to change the

setpoint. The accuracy of the control performed and of the setpoint shall not deviate by more

than 2% of the setpoint value or by 0.5% of the rated power, depending on which yields the

highest tolerance.

(3) A WEFshall be able to receive a Q setpoint with an accuracy of 1 kvar.

4.3.2.2 Power Factor Control

(1) Power factor control is a control function controlling the reactive power proportionally to

the active power at the POC, which is illustrated on Figure 6 by a line with a constant

gradient. The gradient of the line is known as the power factor.

(2) The WEFshall be able to receive a power factor setpoint with an accuracy of 0.001 kvar.


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Figure 6: Reactive Power control for WEF

(3) If the power factor setpoint is to be changed, such change shall be commenced within

two seconds and completed not later than 30 seconds after receipt of an order to change the



highest tolerance.

4.3.2.3 Voltage control

(1) Voltage control is a control function with primary aim of regulating the voltage at the

voltage reference point by controlling the reactive power imported or exported from the WEF.

Voltage control shall have a setting range within minimum to maximum limits, as indicated in

Figure 7.

(2) If the voltage setpoint is to be changed, such change shall be commenced within two

seconds and completed not later than 10 seconds after receipt of an order to change the



highest tolerance.

(3) The WEFshall be able to receive a setpoint with an accuracy of 0.1 kV.

(4) It shall be possible to set the droop in such a way that each individual voltage controller

is able to perform control autonomously. The individual WEF shall be able to perform the


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control within its dynamic range and voltage limit with the droop configured. In this context,

droop is the voltage change (p.u.) caused by a change in reactive power (p.u.).

(5) When the voltage control has reached the WEF's dynamic design limits, the control

function shall await possible overall control from the tap changer or other voltage controlfunctions.

(6) Overall voltage coordination is handled by the NSPin collaboration with the SO.

Figure 7: Voltage control for WEF

4.4 Reactive power control requirements

4.4.1 WEFsof MECless than 20MW

(1) The WEFwith MECless than 20MW shall be designed and operated to supply constant

reactive power output (in Mvar) equivalent to not less than 0.975 lagging and 0.975 leading

calculated at rated active power output (MW), available at the POC under all operating

conditions. Power factor readings shall refer to the POC. This reactive power shall be

available from minimum generation of 20% to full rated active power output.

(2) Figure 8 and Figure 9 illustrate requirement for a WEFwith MECless than 20MW. Point

A is equivalent (in MVar) to 5% rated MW output. Point B is equivalent (in MVar) to 5% rated

MW output.


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+

Figure 8: Reactive power requirement for WEFwith MECless than 20MW

Figure 9 Requirements for voltage control range for WEF with MEC less than 20MW

4.4.2 WEFs of MEC equal or greater than 20MW

(1) The WEF with MEC equal to or greater than 20MW shall be designed to achieve a

constant reactive power limit (in Mvar) of not less than 0.95 lagging and 0.95 leading

calculated at rated MW output, available at the POC under all operating conditions. This

reactive power shall be available from minimum generation of 20% to full rated active power

output.


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(2) Figure 9 and Figure 10 illustrate reactive power and voltage control capability

requirement of a WEF with MEC equal to or greater than 20MW. Point A is equivalent (in

MVar) to -5% rated MW output. Point B is equivalent (in MVar) to 5% rated MW output.

- 0,228- 0,330- 0,410 0,228 0,330 0,410

+

- 0,480

Figure 9: Reactive power requirement for WEFwith MECequal to or greater than 20MW


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Figure 10 Requirements for voltage control range for WEF with MEC equal to or greaterthan 20MW

(3) No WEF wind turbine will consume (import) reactive power from the network in

excess of Q/Pmax > 0.05 for more than 5 seconds in order for it to start up

4.5 Active Power Curtailment

(1) For system security reasons it may also be necessary for the SO or another network

operator to curtail the WEFactive power output.

(2) The WEFshall be capable of:

operating the WEFat a reduced level if active power has been curtailed by the SOfor

system security reasons.

receiving a telemetered MWCurtailment set-point sent from the SO and/or another

network operator. If another operator is implementing power curtailment, this shall be

in agreement with all the parties involved.

4.6 Ramp Rates

(1) The WEFcontrol system shall be capable of controlling the ramp rate of its active poweroutput with a maximum MW per minute ramp rate set by SO.

(2) These ramp rate settings shall be applicable for all ranges of operation including positive

ramp rate during start up, positive ramp rate only during normal operation and negative ramp

rate during controlled shut down. They shall not apply to frequency regulation.

5. Provision of Data and Electrical Dynamic Simulation

Models

(1) The SO and NSPs require suitable and accurate dynamic models, in the template

specified by the requesting party, in order to assess reliably the impact of the WEFproposed

installation on the dynamic performance and security and stability of the power system.

(2) The required dynamic models must operate under EMT simulation to replicate the

performance of the WEF facility or individual turbines for analysis of the following network

aspects:

a. WEFimpact on network voltage stability


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Third stage (after commissioning and optimisation of the WEF)

(a) During this stage, the WEFis compelled to provide information on:

(i) A validated WEF electrical dynamic simulation model using commissioning

test data and measurements

(ii) Test measurement data in the format agreed between the WEFand the NSP

or SO, as applicable.

(4) The dynamic modelling data shall be provided preferably in DigSilent Power Factory

latest format, or any such other format as may be agreed between the WEF and the NSPor

SO, as applicable.

(5) In addition, the WEFshall provide the SOwith operational data as prescribed in section 6.

6. Signals, Communications & Control

6.1 Signals from the WEF to SO

(1) Signals from the WEF to the SOor another network operator shall be broken up into a

number of logical groups. There are different requirements for WEFdepending on the WEFs

maximum sent out capacity or functionality.

(2) The following groups shall apply:

(a)Signals List #1 - applies to all WEFs.

In addition, the WEFshall be required to provide certain signals from Signals Lists 2, 3, 4

and 5. These lists relate to:

(b)Signals List #2 - Wind Energy facility Availability Estimate;

(c)Signals List #3 - Wind Energy facility MW Curtailment Data;

(d)Signals List #4 - Frequency Response System Settings;

(e)Signals List #5 - Wind Energy facility Meteorological Data.

6.1.1 Signals List #1

(1) The WEF generator shall make the following signals available at a NSP designated

communication gatewayfacilitylocated at the WEFsite:

Available MegaWatt sent-out (MW) at the POC

Available Active Power Estimate (MW) at the POC


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Available Reactive Power Import/Export (+/-Mvar) at the POC

On/off status indications for all Reactive Power devices exceeding 5 Mvar;

Ramp rate of the entire WEF


(1) WEF shall make available the following signals at a NSP designated communication

gateway facilitylocated at the WEFsite:

Available MW and forecast MW for the next 6 hours updated hourly on the hour.


(1) The WEF shall make the following signals available at a designated communication


WEFMWCurtailment facility status indication (ON/OFF) as a double bit point.

WEFMWCurtailment Set-point value (MW- feedback) as a double bit point.


(1) The WEFshall make the following signals available at a NSPdesignated communication


Frequency Response Systemmode status indication (ON/OFF) as a double bit point


(1) WEF shall make the following signals available at a NSP designated communication


Wind speed (within 75% of the hub height) measured signal in meters/second;

Wind direction within 75% of the hub height measured signal in degrees from true

north (0-359);

Air temperature- measured signal in degrees centigrade (-20 to 50);

Air pressure- measured signal in millibar (800 to 1400).

(2) The meteorological data signals shall be provided by a dedicated Meteorological Mast

located at the WEFsite or, where possible and preferable to do so, data from a means of the

same or better accuracy. For WEFwhere the wind turbines are widely dispersed over a large

geographical area and rather different weather patterns are expected for different sections of

the WEF, the meteorological data shall be provided from a number of individual

Meteorological Masts, or where possible and preferable to do so, data from a source of the


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same or better reliability for groups of wind turbines. It is expected that wind turbines within an

individual group shall demonstrate a high degree of correlation in Active Power output at any

given time. The actual signals required shall be specified by the SO.

6.2 Update Rates

(1) Signals shall be updated at the following rates:

Analog Signals at a rate of 2 seconds

Digital Signals at the rate of 1 second.

6.3 Control Signals Sent from SO to the WEF

(1) The control signals described below shall be sent from SO to the WEF. The WEFshall

be capable of receiving these signals and acting accordingly.

6.3.1 MWCurtailment Set-point

(1) A telemetered MW Curtailment set-point shall be sent from the SO and/or another

network operator. If another operator is implementing power curtailment, this shall be in

agreement with all the parties involved.

(2) Feedback from the MW Curtailment set-point shall be updated within 2 seconds of

reception of the new value.

6.3.2 Ramp Rates

(1) A telemetered Ramp rate shall be sent to the WEF from the SO and/or another network

operator. If another operator is implementing power curtailment, this shall be in agreement

with all the parties involved.

(2) Feedback from the MW Curtailment set-point shall be updated within 2 seconds of

reception of the new value.

6.3.3 Connection Point Circuit Breaker Trip facility

(1) A facility shall be provided by the NSPto facilitate the disconnection of the WEF. It shall

be possible for SO or another network operator to send a trip signal to the circuit breaker at

the HVside of WEFPOC


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6.4 MW Forecast

(1) MW forecasts shall be provided by WEF generator. These forecasts shall be provided at

10:00 a.m. on a daily basis for the following 48 hours for each 1 hour time-period, by means

of an electronic interface in accordance with the reasonable requirements of SOs data

system.

6.5 Data Communications Specifications

(1) The WEFshall have an external communication gateway facility that can communicate

with a minimum of three simultaneous SCADA Masters, independently from what is done

inside the WEF.

(2) The location of the communication gateway facility shall be agreed between affected

participants in the connection agreement.

(3) The necessary communications links, communications protocol and the requirement for

analogue or digital signals shall be specified by the SOas appropriate before a connection

agreement is signed between the WEFgenerator and the NSP.

(4) Active Power Curtailment, Frequency Response or Voltage Regulation facilities at the

WEFwill be tested once a month. It is essential that facilities exist to allow the testing of the

functionality without tripping the actual equipment.

(5) Where signals or indications required to be provided by the WEFbecome unavailable or

do not comply with applicable standards due to failure of the WEF equipment or any other

reason under the control of the WEF, the WEFgenerator shall restore or correct the signals

and/or indications within 24 hours.

7. Protection facilities

(1) Protection functions shall be available to protect the WEFand to ensure a stable TSand

DS.

(2) The WEF generatoris responsible for ensuring that a WEFis dimensioned and equipped

with the necessary protection functions so that the WEF is protected against damage due to

faults and incidents in the TSand DS.


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(3) The NSPor the SO is entitled to request that the set values for protection functions be

changed following commissioning if it is deemed to be of importance to the operation of the

TSand DS. However, such change shall not result in the WEFbeing exposed to impacts from

the TSand DSlying outside of the design requirements specified in section 4.1.2.

(4) The NSPshall state the highest and lowest short-circuit current that can be expected at

the POC as well as any other information about the TS and DS as may be necessary to

define the WEF'sprotection functions.

8. Compliance Monitoring

(1) The WEFshall be required, prior to commercial operation, to demonstrate to the SOand

the relevant NSP full compliance to all requirements of this code and related sections in the

Distribution Codeand the Grid Code.

(2) While in operation the WEF generator shall report any material deviation from the

requirement of this code to the SOand the local network operator within 2 days after being

aware of such deviation.

9. Reporting

(1) The WEF operator shall maintain records of and provide to the NERSA on a monthly

basis in electronic spreadsheet format the following:

Non-renewable/supplementary fuel used by the power plant as outlined under

Supplementary Fuel Specification schedule of the power purchase agreement (PPA)

during the month.

Day ahead forecast hourly availability, sent out energy, gross energy and wind speed.

Actual hourly availability sent out energy, gross energy and wind speed.

Direct monthly emissions per unit of electricity generated by the WEF(tCO2/kWh).

Any curtailed energy during the month.


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APPENDIX A WEF COMPLIANCE TESTING

1. INTRODUCTION

This section specifies the preferred connection process WEFs should follow to achieve

Commercial Operation (CO). CO is required to allow WEF to synchronise and export

power onto the TS or DS. In addition the document describes in greater detail technical

studies and testing which demonstrate compliance with the Connection Conditions

section of the Grid Code.

1.1 Ongoing monitoring of a units performance

WEF generators shall monitor each of their WEF during normal service to confirm

ongoing compliance with the applicable parts of this code. Any material deviations

detected must be reported to the relevant NSP and/ or System Operator within five

working days.

WEF generatorsshall keep records relating to the compliance by each of their WEFwith

each section of this code applicable to that WEF, setting out such information as the

System Operatoror NSP reasonably requires for assessing power system performance

(including actual WEFperformance during abnormal conditions).

1.2 Scheduling of Grid Code compliance testing

Contact details are to be exchanged between the designated contacts from Transmission

or Distribution and the WEF generator prior to the scheduling of Grid Code compliance

testing. These designated contacts will be the primary points of contact between the IPP

and Transmission or Distribution throughout the Grid Code compliance process, from

scheduling of testing to the carrying out of testing, unless otherwise indicated by either

party.

When the WEF generator is satisfied that the WEF is fully compliant with the Grid Code

with the exception of any exemptions or derogations approved by NERSA, a request

should be sent to SO and the relevant Transmission Network Service Provider (TNSP) or

Distributor to schedule a date for Grid Code compliance testing of the WEF. This should

be sent no later than three weeks prior to the proposed date of the test.

Along with the test request, the following information should be provided by the WEF

generator:


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1) Overall single line diagram of the WEF

2) Technical data including reactive power capability curve for the WEF

3) Directions to the WEF

4) Site map for the WEF5) Contact details of appropriate personnel on site (if different from designated WEF

generator contact)

SO and the relevant TNSP or Distributor will consult with the relevant parties to ensure

that the personnel required for testing will be available on the date requested. However, if

the necessary personnel are not available on the date requested by the WEF generator,

parties shall agree on the most appropriate date which is convenient to all. A testing start

time is to be agreed with the SO and the relevant TNSP or Distributor one week prior to

the scheduled day of testing.

Verification of the wind conditions a week prior to, and a day prior to the scheduled date

of Grid Code compliance testing is required to be carried out by the WEF generator and

communicated to the SO and the relevant TNSP or Distributor. Insufficient wind

conditions may lead to the cancellations of testing up to 1 day prior to testing. Note that at

any time prior to, or during Grid Code compliance testing, the SO and the relevant TNSP

or Distributor reserve the right to cancel or postpone testing for system security reasons.

1.3 Day of Grid Code Compliance Testing:The relevant TNSP or Distributor representative shall witness testing on site, unless

otherwise agreed. The TNSP or Distributor representative shall liaise with the SO, in

particular the National Control operators and personnel on site to coordinate testing.

Results of the tests consisting of data and graphs should be provided by the WEF

generator test coordinator to the SO and the relevant TNSP or Distributor representative

in both hard copy and electronic file format.

In addition, the WEF generator is required to prepare a report for tests on the WEF which

shall include all tests carried out and the data results collected during testing, along with

the raw data from which the data results were extracted. A copy of the WEF generators

report shall be made available to SO at which point SO will assess compliance in a timely

manner.


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1.4 Format of Data

WEF generators are requested to submit all data in standard formats for incorporation

into SOs information management system and forward to the relevant TS/ DS.

Unless otherwise agreed submissions should be in the following file formats.

1) Specifications, Agreements and Technical Reports in PDF format

2) Signed Documents in scanned PDF format.

3) Test result data points in XLS format (e.g. Excel )

4) Performance Charts/Plots PDF and/or XLS format.

5) Drawings in PDF format.

6) Simulation Models in the form of transfer function block diagrams (using PDF)

Where documents and diagrams are provided as supporting information, they should be

legible and should include all relevant data assumptions (for example generator base,

p.u., percentage values etc).

Where testing and monitoring results are provided they should be legible, appropriately

sized, scaled and labelled.

1.5 Available Signals

The WEF should ensure that the following signals are available and are terminated at a

single location for the purpose of connecting TS/ DSs and the WEFs own recording

equipment.

1) Total MW

2) Total MVAr

3) Point of connection line-line Voltage (kV)

4) System frequency (Hz)

5) Injected signal (Hz / Volts as appropriate) or test logic signal

6) Available power (MW)

7) Power source speed (e.g. wind speed m/s)

8) Power source direction (degrees)

9) WEF site voltage (kV)

10) Any other signals as agreed between the WEF and NSP/ SO.

As a minimum, signals 1-4 should be available as dc voltages for NSP/ SO to monitor on

site. In some cases the remaining signals may only be available from the WEF control

systems as a download once the testing has been completed. NSP/SO will agree to this

provided the full test results can be provided within 5 working days to SO with all data at


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the appropriate resolution depending on the type of test. This solution should not

unreasonably add a significant delay between tests or impede the volume of testing which

can take place on the day.


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2. COMPLIANCE TEST

2.1 TEST 1: Reactive Capability

WEF Compliance Testing / Monitoring

Title of Test: Reactive Capability Test Number: 1

Description & Purpose of Test:

The WEF shall demonstrate its technical capability to operate to the limits of the

applicable reactive power capability curves as indicated in section 4.4 of the wind grid

code. The test shall be undertaken for both leading (consumption) and lagging

(production) reactive power to the WEF. This test should be undertaken at different levels

of active power to confirm that the range is within the capability characteristic at the given

level of power. The test should be undertaken at the Voltage slope setting of 4%. The grid

voltage set-point should be under the control of SO or the relevant Network Operator.

Verification of reactive power capability can be achieved by operation of the Power Park

Module at following load points for the specified durations.

Test 1.1) Operation in excess of 50% Rated MW and maximum lagging reactive power for 60

minutes.

Test 1.2) Operation in excess of 50% Rated MW and maximum leading reactive power for 60

minutes.

Test 1.3) Operation at 20% Rated MW and maximum leading reactive power for 5 minutes.

Test 1.4) Operation at 20% Rated MW and maximum lagging reactive power for 5 minutes.

Test 1.5) Operation at less than 20% Rated MW and unity power factor for 5 minutes This testonly applies to systems which do not offer voltage control below 20% of rated power.

Results Required:

As a minimum the following data for each test must be recorded and submitted to NSP/

SO with the appropriate resolution specified by relevant NSP or SO.

MW - Active power at the applicable measurement point.

MVAr - Reactive power at the applicable measurement point.

System Voltage at POC.

Test Assessment

The test results will be assessed against:

Section 4.4 of the Wind Grid Code

Criteria of Assessment

The tests will be regarded as supporting compliance if:

The reactive power required in each test is achieved within a tolerance of 5%.

The tests will record and verify the performance chart of the overall WEF submitted to

NSP or SO.


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2.2 TEST 2: Voltage Control


Title of Test: Voltage Control Test Number: 2

Description & Purpose of Test:The WEF shall demonstrate the technical capability to regulate the grid voltage at the

connection point to a value set by SO or relevant Network Operator. Such regulation shall

be within the capability of the WEF to regulate the voltage at this point taking account of

the short circuit level at the connection point, regulation of the grid connected transformer,

the voltage slope (droop) applied to the WEF and the reactive capability of the WEF.

Results Required:





Voltage at controlled busbar, usually the POC.

Power System Stabilizer (if fitted) Internal PSS Control Signal

Intermittent Power Resource (e.g. wind speed)

Power Available

Other signals relevant to the control action of the voltage controller as specified

by NSP or SO.

Test Assessment


Section 4.3.2.3 of the Wind Grid Code



An appropriate proportion of the full reactive capability of the WEF is delivered

within 1 second.

The change in reactive output commences within 0.2s of the application of thestep injection

Any oscillations settle, to within 5% of the change in steady state reactive power

within 2 seconds of the application of the step injection.

The final steady state reactive value according to the slope characteristic is

achieved within 5 seconds of the step application.

Adjustable slope characteristic, 2 to 7%. NB The slope is calculated in terms of

rated Power Factor, for example a 4% droop should result in a 4% change in

volts when moving from unity PF to 0.95 exporting or importing.


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2.3 TEST 3: Frequency response performance


Title of Test: Frequency response performance Test Number: 3


The WEF shall demonstrate the technical capability to continuously modulate active

power to contribute to frequency control; validate the frequency controller model

submitted to NSP or SO, assess dead-band, incremental droop, steady state/dynamic

stability of the frequency controller and demonstrate the robustness of the control system. Where a WEF (or a number of WEFs) has been Type Registered for frequency controller

response performance, a reduced set of compliance tests may apply provided NSP/ SO

deems the data held in the Type Register to be appropriate. In this case only the following

confirmatory tests need be completed;

1) A +0.8Hz ramp over 30 seconds with the WEF in Limited Frequency Sensitive Mode from

maximum available power

2) A +0.5Hz ramp over 10 seconds with the WEF in Frequency Sensitive Mode from a

sufficient de-load point to allow unconstrained operation

3) A -0.5Hz ramp over 10 seconds with the WEF in Frequency Sensitive Mode from a

sufficient de-load point to allow unconstrained operation

If these tests do not correspond to the performance demonstrated in the data held in the

Type Register then a full set of compliance tests will have to be conducted as outlined byNSP/ SO.

Results Required:




Injected signal


Voltage at controlled busbar, usually the POC.

Power System Stabilizer (if fitted) Internal PSS Control Signal

Intermittent Power Resource (e.g. wind speed)

Power Available

Other signals relevant to the control action of the voltage controller as specified

by NSP or SO.

Test Assessment



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The reactive power required in each test is achieved within a tolerance of 5%.

The tests will record and verify the performance chart of the overall WEF submitted to

NSP or SO.


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2.4 TEST 4: VOLTAGE AND CURRENT EMISSIONS TEST


Title of Test: Voltage and Current emission test Test Number: 4

Description & Purpose of Test:The purpose of this test is to confirm the ability of the WEF to operate within the limits

specified by the TNSP or the relevant Distributor. This test shall take place while other

grid code compliance tests are being undertaken which are within the normal operating

parameters of the WEF. Such measurements shall be undertaken at both WEF voltage

and at grid voltage and will be referred to collectively as power quality tests.

Results Required:

voltage fluctuations:

a. rapid voltage changes

b. flicker

high-frequency currents and voltages:

a. harmonics

b. inter-harmonics

c. disturbances greater than 2 kHz.

Test Assessment




The test results will be regarded as supporting compliance if:

The emissions are within limits allocated by the TNSP or the relevant Distributor.


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2.5 TEST 5: Fault Ride Through, fault Contribution and Power Recovery


Title of Test: Fault Ride Through, Fault

Contribution and Power Recovery

Test Number: 5


NSP/ SO requires verification by using a simulation model that the WEF has the capability

to ride through faults on the TS or DS within limits stated in section 4.1.3 and 4.1.4.

Results Required:

WEF Model Validation study

Test Assessment

The simulation results will be assessed against:

Section 4.1.3 and 4.1.4 of the Wind Grid Code


The simulation regarded as supporting compliance if:

WEF stays connected to TS/ DS within the limits stated in 4.1.3.

WEF prioritises the supply of reactive power over the supply of active power.

WEF maintains the active power within the design limits stated

WEF cuts off the grid connection when the limits stated are exceeded