Upgrade of New Zealand HVDC Pole III s

IEEE Power Engineering Society General Meeting 2014 Washington DC, USA

1

Topics to be covered

• New Zealand HVDC Inter-Island Link – System overview

• Site Specific Conditions – Seismic Design Requirements

• Design Coordination between Existing and New Plant • New Control Functions

2

System Overview • Customer: Transpower NZ • Transmission Asset Owner and System

Operator in New Zealand • Bipole with land- and shore electrodes

• Pole 1 (1965) Mercury Arc Valves

• Pole 2 (1992) Thyristor Valves • 40 km Submarine Cable • 570 km Overhead Line • 220 kV AC / 110 kV AC

3

Benmore

Haywards

Benmore

Haywards

Historical Perspective** 4

Pole 1 – Mercury Arc Valves (1965)

Pole 2 – Thyristors (1992)

** New Zealand Inter Island HVDC Pole 3 Project CIGRE SCB4 Colloquium 2011, Brisbane, Australia 19-21 October 2011. Peter Griffiths, Transpower

HVDC link Until 2013 (Pole1 & Pole2)

5

BENMORE220 kV

HAYWARDS220 kV

Cable 6

Cable 4

Pole 2 (existing thyristor

Converters 700 MW)

535 km DC line section – South

Island

35 km DC line section

North Island

40 km Cook Strait Cables

+ 270 kV

- 350 kV

Cable 5

HAYWARDS110 kV

C7BENMORE

16 kV

Ground (Earth/Sea) Return Current mode

F479.3 Mvar

79.3 Mvar

F3

F3

F4

106.3 Mvar

106.3 Mvar

C1

60 Mvar

T1

C4C335 Mvar

each

T5

C2 60 Mvar

T2

40 MvarR5

40 Mvar

R1

F2

50.5 Mvar

50.5 Mvar

F1

F247.5 Mvar

47.5 MvarC8

C9

C10Pole 1 assets

Pole 2 assets

VG3

VG4

P1B

VG2

VG1

P1A

F1

HVDC Pole 3 Project - Design 6

BENMORE220 kV

HAYWARDS220 kV

Pole 2 ( existing thyristorConverters 700 MW)

535 km DC line section – South

Island

40 km Cook Strait Cables

35 km DC line section

North Island40 km Cook Strait

Cables

+ 350 kV

- 350 kV

Pole 3(new thyristor

converters 700 MW)

HAYWARDS110 kV

C7

C8

C9

C10

BENMORE16 kV

F3

F4

79.3 Mvar

79.3 Mvar

Stages 1&2

Existing

Stage 3

F3

F4

106. 3 Mvar

106. 3 Mvar

C7-C1065 Mvar

each

Cable 6

Cable 4

Cable 5

Cable 7

4 0 Mvar

C1

60 Mvar

T1

C4C335 Mvar

each

T5

C2 60 Mvar

T2

R5

4 0 Mvar

R1

Reactive Power Supplyto Pole 3 at Haywards

Reactive Power Supplyto Pole 3 at Benmore

New 220kV Reactive Plant

Stages 1&2

New 220kV Reactive Plant

Stage 3

New 220kV Reactive Plant

And SVS Stages 1&2

New 220kV Reactive Plant

Stage 3

16 Mvar

16 MvarF8

F7

Seismic Design Aspect

• Both Converter Stations must have High Level of Seismic Resilience, particularly Haywards which is located only a few hundred meters from an active geological fault line

• Structural diversity between the new Pole 3 and the existing Pole 2 in an attempt to avoid common mode failures

• Seismic isolation of the converter building housing the thyristor valves, converter transformers and control / auxiliary system

•

7

Converter Building Seismic Isolation

8

Reactor & Bushing 9

• Reactor isolation • Shake table test

Design Coordination between Existing and New Plant

• Arrester arrangement including all existing arresters – V-I characteristics – Protective levels of the new surge arresters

• Existing Pole 1 DC filters, built identical to Pole 2 DC filters • Various components installed at the DC neutral bus need to

be replaced by components with higher rating

10

Reactive Power Control 11

AC Filters

• Overall filter design will ensure that the new AC filters do not cause undue loading of the existing filters during operation

• Wider AC frequency range (+/-2 Hz) • Triple-tuned AC filters TT11/13/24 have been

designed considering • 3rd harmonic filters (ST LO3) will be installed at

Benmore taking potential resonances of pre-existing low order harmonics into account

12

Stability, Modulation and Frequency Control*

• Supplementary Modulation Controls and Runbacks are implemented in the HVDC Control System – Weak AC grid – Increased power transfer capability

• DC current modulation to damp voltage swing • Frequency controls • Fast run backs • Round power mode *1400 MW New Zealand HVDC Upgrade: Introducing Power Modulation Controls and Round Power Mode Simon P. Teeuwsen, Geoffrey Love, Richard Sherry, Power and Energy Society General Meeting (PES), 2013 IEEE

13

Special Controls

Frequency Stabilization Control

14

Time Domain Simulation Results 15

Special Controls (Contd…)

Spinning Reserve Sharing

16

Time Domain Simulation Results 17

Special Controls (Contd…) Frequency Keeping Control

18

Constant Frequency Control

Round Power Mode 19

PDC

Pref

Bipole PowerPole 2 PowerPole 3 PowerPmin POLE = 35MW

Mon

opol

e Tr

ansi

tion

Leve

l

RP

Tra

nsiti

on L

evel

Pmin RP

Pmin RP

+Pm

in B

P

-Pm

in B

P

Mon

opol

e Tr

ansi

tion

Leve

l

Round Power Operation

Monopolar Operation P3

Bipolar Operation

Monopolar Operation P2

Bipolar Operation

RP

Tra

nsiti

on L

evel

Time Domain Simulation Results 20

Thank you

Siemens Energy Inc, USA

21