Introduction South African Renewable Energy Grid Code Version 2.8

Requirements Test procedures

Conclusion

Gas Collector Wells in

Landfill Site

Landfill Gas Pump

& Flare StationLandfill Gas Engine and

Electricity Generator

Step-up

Transformer

Switchgear &

Control Room

Generation of Landfill Gas

(CH4, CO2)

Destruction of

Methane (CH4)

Generation of

Electricity

Supply to Municipal

Electricity Grid

GE Jenbacher

It accordance to the Electricity Regulation Act (Act 4, 2006), it is mandatory forall Renewable Power Plants (RPP) connecting on the Eskom/Municipalitytransmission or distribution grid to comply with the requirements of the SouthAfrican Renewable Energy Grid Code (SAREGC).

However the requirements and testing methods of the SAREGC Version 2.8 isnot well understood by many.

This presentation willserve to discuss therequirements from theSAREGC Version 2.8and possible methodsto conduct grid codecompliance testing forRPP in South Africa.

Photovoltaic Plants

Concentrated Solar Power plants

Wind power plants

Small hydro power plants

Biomass power plants

Biogas power plants

Landfill gas power plants

Category Minimum

Size kVA)

Maximum

Size (kVA)

Type

A1 0 13.8 LV connected

A2 13.8 100 LV connected

A3 100 1000 LV connected

B 0 20000 MV connected

C >20000 MV/HV

connected

Grid Code Category

classification of

Renewable Power

Plants

REIPPPP: Round 1 – 4 Projects

The RPP needs to

remain connected in

Area A, B and D

The RPP may

disconnect in Area C

The RPP must withstand

voltage drops to zero for

150 milliseconds

For voltages up to

120%, the RPP needs

to remain connected

Reactive Power Support during Voltage Drops and Peaks

The RPP needs to absorb

reactive power once the

voltage exceeds 110%

Area A, RPP not required

to absorb or supply Q

The RPP needs to

absorb maximum

reactive power

The RPP needs to

inject maximum

reactive power once

the voltage reduce

below 50%

The RPP must withstand voltage drops to zero for

150 milliseconds

V = 0 Volts

Maximum Q

Minimum P

VRTC for Category B and RPP

Control Function Category B Category C

Frequency Control - ˣAbsolute Production Constraint ˣ ˣDelta Production Constraint - ˣPower Gradient Constraint ˣ ˣReactive Power (Q) Control ˣ ˣPower Factor Control ˣ ˣVoltage Control ˣ ˣ

Frequency Response Requirement from Category C RPP

Over FrequencyUnder Frequency

Frequency Response Requirement from Category C RPP

Formulae for the

calculation of

Droop

Droop is defined

as a percentage

of the frequency

change required

for an RPP to

move from no-

load to rated

Power or from

rated power to

no-load

Frequency Response

Requirement from Category C

RPP

Over Frequency Event

– Supply > Demand,

RPP needs to reduce

output power following

the selected Droop 2

setting for increase in

frequency

Under Frequency Event – Demand > Supply,

RPP needs to Supply PDelta as per selected

Droop 1 for reduction in frequency

Grid Code Compliance Testing for Under Frequency Response

Plant supplying

PDelta in an under

frequency situation

Deactivation

of PDelta

49 Hz

48 Hz

49.5 Hz

50 Hz 49.85 Hz 50 HzSet Point 1

Set Point 2 Set Point 3

Set Point 4

Set Point 5

Enable PDelta

FREQ SET POINT 0: 50 Hz

f SET POINT 1: 49.85 Hz

f SET POINT 2: 49.5 Hz

f SET POINT 3: 49 Hz

f SET POINT 4: 48 Hz

f SET POINT 5: 50 Hz

Set Point 0

Reactive Power

Capability Testing at

PAvailable which is ≥

20% of PMax

QMax Cat B: Q/PN = 0.228

QMax Cat C: Q/PN = 0.33QMin Cat C: Q/PN = - 0.33

QMin Cat B: Q/PN = - 0.228

Reactive Power Capability

Testing at PAvailable and

P = 20% PMax

Un

UMax

UMin

TEST @ U = 1 PU

Q SET POINT 1: 0 MVAr

Q SET POINT 2: QMAX

Q SET POINT 3: 0 MVAr

Q SET POINT 4: QMIN

Q SET POINT 5: 0 MVAr

TEST @ U = UMax

Q SET POINT 1: 0 MVAr

Q SET POINT 2: QMin

Q SET POINT 3: 0 MVAr

TEST @ U = UMin

Q SET POINT 1: 0 MVAr

Q SET POINT 2: QMax

Q SET POINT 3: 0 MVAr

Category B RPP

[-0.228 ≤(Q/PMax)≤0.228] at U = 1PU

Category C RPP

[-0.33 ≤(Q/PMax)≤0.33] at U = 1PU

Set Point 5

Q = 0 MVAr

Set Point 3

Q = 0 MVAr

Set Point 2

Q = QMax

Over Excited

Set Point 1

Q = 0 MVAr

Set Point 4

Q = QMin

Under Excited

U = 1 PU

SET POINT 1: Q = 0 MVAr

SET POINT 2: Q = QMax (Over Excited)

SET POINT 3: Q = 0 MVAr

SET POINT 4: Q = QMin (Under Excited)

SET POINT 5: Q = 0 MVAr

PF = 1 (Unity)

PF = 0.975 (Cat B)

or 0.95 (Cat A) PF = 0.975 (Cat B) or

0.95 (Cat C)Over excited - Leading

Under excited - Lagging

TEST @ P = PAvailable

& P = 20% PMax

PF SET POINT 1: UNITY

PF SET POINT 2: PF MAX

PF SET POINT 3: UNITY

PF SET POINT 4: PF MIN

PF SET POINT 5: UNITY

1 2345

Set Point 1

PF = Unity

Set Point 3

PF = Unity

Set Point 5

PF = Unity

Set Point 4

PF = -0.95

Under Excited

Set Point 2

PF = 0.95

Over Excited

Power Factor Control

Function Testing

Test at P = PAvailable and

P = 20% PMax

PF SET POINT 1: UNITY

PF SET POINT 2: 0.95

PF SET POINT 3: UNITY

PF SET POINT 4: -0.95

PF SET POINT 5: UNITY

Power

Gradient

Constraint

Power Gradient

Constraint

Delta Production

Constraint

Absolute

Production

Constraint

Absolute Production Constraint

An Absolute Production Constraint Function is used to constrain the

output active power from the RPP to a predefined power MW limit at

the POC.

This is typically used to protect the network against overloading.

Absolute

Production

Constraint

Available

Active

Power

PReference

80% PReference

40% PReference

20% PReference

10% PReference

30% PReference

50% PReference

80% PReference

0% PReference

1

2

3

4

5

6

7

8

Testing of the RPP Active Power Constraint Function

Select PReference

SET POINT 1: 80% PRef

SET POINT 2: 40% PRef

SET POINT 3: 20% PRef

SET POINT 4: 10% PRef

SET POINT 5: 30% PRef

SET POINT 6: 50% PRef

SET POINT 7: 80% PRef

SET POINT 8: 0% PRef

SET POINT 9: PReference

100% PReferencePAvailable

9

A Delta Production Constraint function is used to constrain the

active power from the RPP to a required constant value in

proportion to the possible active power.

It is typically used to establish a control reserve for frequency

control during under frequency conditions.

PDelta

0.00

5.00

10.00

15.00

20.00

25.00

30.00

02:2

1:57

PM

02:2

2:16

PM

02:2

2:35

PM

02:2

2:54

PM

02:2

3:13

PM

02:2

3:32

PM

02:2

3:51

PM

02:2

4:10

PM

02:2

4:29

PM

02:2

4:48

PM

02:2

5:07

PM

02:2

5:26

PM

02:2

5:45

PM

02:2

6:04

PM

02:2

6:23

PM

02:2

6:42

PM

02:2

7:01

PM

02:2

7:20

PM

02:2

7:39

PM

02:2

7:58

PM

02:2

8:17

PM

02:2

8:36

PM

02:2

8:55

PM

02:2

9:14

PM

02:2

9:33

PM

02:2

9:52

PM

02:3

0:11

PM

02:3

0:30

PM

02:3

0:49

PM

02:3

1:08

PM

02:3

1:27

PM

02:3

1:46

PM

02:3

2:05

PM

02:3

2:24

PM

02:3

2:43

PM

02:3

3:02

PM

Pow

er (M

W)

Wind Farm Test Results - Delta Production Constraint @ 10%

Actual Power (MW) Available active power

PDelta Setting (%) 10 second average

PDelta set at 10% PAvailable

Activate PDelta Deactivate PDelta

A Power Gradient Constraint Function is used to limit the RPP

maximum ramp rates by which the active power can be changed in

the event of changes in primary renewable energy supply or the set

points for the RPP.

A Power Gradient Constraint is typically used for reasons of system

operation to prevent changes in active power from impacting the

stability of the network.

Test 1

Select PReference

Set Ramp Rate:

(0.4 ˣ PReference/minute)

Set Point 1: PRef to 20% PRef

Set Point 2: 20% PRef to PRef

Test 2

Set Ramp Rate:

(0.2 ˣ PReference/minute)

Set Point 1: PRef to 20% PRef

Set Point 2: 20% PRef to Pref

PAvailable

PReference

20% of PReference

PReferencePReference

20% of PReference

Ramp Rate

0.4 × Preference/min

Ramp Rate

0.2 × Preference/min

2 Minutes 4 Minutes

Set Ramp Rate:

(0.4 ˣ PReference/minute)

Test 1: PRef to 20% PRef

Test 2: 20% PRef to PRef

Set Ramp Rate:

(0.2 ˣ PReference/minute)

Test 1: PRef to 20% PRef

Test 2: 20% PRef to PRef

2 Minutes4 Minutes

Power Quality is required to be monitored at the POC and the following

parameters shall be monitored:

a) Rapid Voltage Change

b) Flicker

c) Harmonics

d) Unbalance voltage and current

The PQ limits given by the NSP to the IPP are apportioned values

which takes the PQ limits given in NRS 048 and apportioned to the

upstream contribution together with current and future customer’s

contribution limits.

Power Quality testing is done utilising a Power Systems Simulation

Package.

Actual Site Measurements taken over a period of time.

Based on results, the IPP may need to install Harmonic Filtering

Equipment.

Example of Signals brought back via SCADA

There are many opportunities for renewable energy generation in

South Africa with supporting programs such as the REIPPPP.

Compliance to the South African Renewable Energy Grid Code is

mandatory and all RPPs must comply with the code at the point of

connection onto the utility grid

The SAREGC Version 2.8 is currently undergoing further changes to

include more detailed protection requirements, power quality

requirements and amendments to the requirements from certain

types of RPP technology.

This paper provides a simple introduction to utilities and developers

on the SAREGC requirements and provide some practical testing

methods that can be employed to prove grid code compliance of

RPPs.

Comments & Questions???