Manapouri 220kV Voltage ControlRowan Sinton

MERIDIAN ENERGY LIMITED 2

3) Working with

Transpower:vs.

Bus

Voltage

Generator

Voltagevs.2) Voltage control:

MVAr

Dispatch

Continuous

Voltage

Controlvs.1) AVR mode:

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Can you do both?

MVAr

Dispatch

Continuous

Voltage

Controlvs.

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AVR

Actual

Voltage

220 kV bus

GSU

Voltage

Setpoint

Non-infinite bus

MVArNo OLTC

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AVR

Actual

Voltage

GSU

Voltage

Setpoint

10 MVAr

220 kV bus

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AVR

“Superimposed”

MVAr control

MVAr

Setpoint

SCADA

220 kV Bus

GSU

Actual

VoltageVoltage

Setpoint

Actual

MVAr

MERIDIAN ENERGY LIMITED 7

AVR

“Superimposed”

MVAr control

MVAr

Setpoint

SCADA

220 kV Bus

GSU

Actual

VoltageVoltage

Setpoint

Actual

MVAr

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Superimposed MVAr mode – done badly

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How long to stay in “superimposed MVAr mode”?

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Yes you can (and must) do both, but:

• Be careful with superimposed MVAr control

• Loosen your definition of “continuous voltage control”

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• Is the dispatched voltage at the generator terminals or bus voltage (GIP)?

• Does the dispatch have to be continuously met?

• Should all asset owners already be able to do this?

Bus

Voltage

Generator

Voltagevs.

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220kV Bus Voltage Control Mode

AVR

Bus

Control

Bus Voltage

Setpoint

220 kV Bus

GSU

Actual

Generator

Voltage

Generator

Voltage

Setpoint

SCADAActual

Bus Voltage

MERIDIAN ENERGY LIMITED 13

Bus voltage control – done well

\\PISERVER\ANALOG:MAN_SS.FB_VCTRL_MAN

225.93

Volts

\\PISERVER\ANALOG:MAN_SS.STN3_KV

225.93

kV

MAN SS Volt Ctrl MAN Setpoint FB MAN SS 220kV Station Voltage

8:30 8:00 7:00 6:30

4/12/2017 9:00:00 a.m.Plot-0

220

221

222

223

224

225

226

227

228

229

230

MERIDIAN ENERGY LIMITED 14

Bus

Voltage

Control

Generator

Voltage

Controlvs.2)

• Is the dispatched voltage at the generator terminals or bus voltage (GIP)?Presumably bus voltage

• Does the dispatch have to be continuously met?Presumably yes

• Should all asset owners already be able to do this?Requires the asset owner to implement a bespoke control system

MERIDIAN ENERGY LIMITED 15

Working with Transpower after theMAN bus voltage “out of control” event

• Transpower approached Meridian on an engineering level first

• There was no formal breech…

• … but threats were made

• Meridian provided all available information – no secrets

• Transpower provided prompt and useful guidance

• Transpower followed up to ensure all actions were closed

MERIDIAN ENERGY LIMITED 16