grid forming offshore wind turbines towards power system ......offshore ac network start-up options...

© PROMOTioN – Progress on Meshed HVDC Offshore Transmission Networks This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 691714.

Grid Forming Offshore Wind Turbines towards Power System Black Start

Ömer Göksu, DTU Wind Energy 31 October 2018, Wind Energy Denmark 2018, Hedensted


PROMOTioN WP3 ◦ WTG – Converter Interaction WP3 Partners

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PROMOTioN WP3 ◦ WTG – Converter Interaction Grid Forming Wind Turbines – for Diode Rectifier HVDC connection

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GearBox

Generator

WT transformer

WPP transformer

WT transformer

ACDC AC

DC

HVDC transformer

VSC - HVDC Offshore HVDC

Onshore

Onshore AC Grid

WT Control

Offshore Voltage & Frequency

ACDC

ACDC

GearBox

Generator

ACDC

ACDC

WT Control

Active & Reactive Power

Active & Reactive Power

Grid following wind turbines

GearBox

Generator

WT transformer

WT transformer

ACDC AC

DC

Diode Rectifier Unit HVDC Onshore

Onshore AC Grid

WT Control

ACDC

ACDC

GearBox

Generator

ACDC

ACDC

WT Control

Active & Reactive PowerVoltage & Frequency Control

Grid forming wind turbines

Active & Reactive PowerVoltage & Frequency Control

Grid forming wind turbines control - dq current control based

- droop based - voltage/angle control based - GPS synchronization based

- master/slave based


PROMOTioN WP3 ◦ WTG – Converter Interaction Offshore AC Grid Start-up Options - DRU

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VSC-MMC

VSC-MMConshore

HVDC link

VSC-MMConshore

DRUs

Onshore AC Grid

Umbilical AC Cable Nearby VSC-HVDC (or AC)

HVDC link

VSC-MMConshore

DRUs

Energy Storage

Local Energy Storage (e.g. battery, diesel)

HVDC link

VSC-MMConshore

DRUs

es

es

es

Black-startable wind turbines


PROMOTioN WP3 ◦ WTG – Converter Interaction Offshore AC Network Start-up Options - VSC

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HVDC offshore terminal

VSC-MMC

HVDC link

VSC-MMConshore

In case of normal conditions Energization from onshore

Energy Source

In case of offshore grid outage Offshore Energy Source (e.g. diesel generator)

ESES

ES

ES

In case of offshore grid outage or collection system failure Black-startable wind turbines


PROMOTioN WP3 ◦ WTG – Converter Interaction Black Start by Offshore Wind Turbines

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Step 1 Self-start of

Wind Turbine

Step 2 Self-Energization of Wind Power Plant

Step 3 Contribution to Grid

Restoration

Objective: To avoid issues of non-operating wind turbines; - Moisture - Icing - Vibrations - Deformation

Objective: To energize WPP and substations (AC and HVDC) auxilary w/o any external supply

Objective: To provide black start for the onshore power system

- Wind turbines will start w/o grid voltage

- Wind turbines will supply themselves using wind (houseload operation)

WPP will operate similar to the conventional black start units

WPP will energize up to the onshore PoC


PROMOTioN WP3 ◦ WTG – Converter Interaction Generic Self-Energization Sequence

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Gearbox

Synchronous Generator

Filter

Rotor-side VSC

(RSC)

Grid-side VSC

(GSC)

WT-DC WT Transformer

Battery energy storage system

(BESS)

UPS

Self-start

Self-

sust

ain

Chopper

FilterArray cable

DG

Auxiliaries+

Controller

Type 4Variable-speedWind Turbine

(WT)


Gearbox


Filter

Rotor-side VSC

(RSC)

Grid-side VSC

(GSC)


Array cables


(BESS)

UPS

WPP Transformer

OWPP substation

Export cable

WTStrings

Self-start

Self-

sust

ain

Para

llel

oper

atio

n

Chopper

FilterArray cable

DG

Auxiliaries+

Controller


(WT)

DG

Offshore Wind Power Plant

(OWPP)Diesel generator

backup


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Gearbox


Filter

Rotor-side VSC

(RSC)

Grid-side VSC

(GSC)


Array cables


(BESS)

UPS

WPP Transformer

OWPP substation

Export cable

WTStrings

WPP2

WPP1

ONshore converter transformer

PCC

Onshore AC gridONshore-VSC

(Inverter)

OFFshore ONshore

Self-start

Offshore HVDC substation

OFFshore converter transformer

HVDC Cable link

OFFshore-VSC(Rectifier)

Onshore HVDC substationBackup

Self-

sust

ain

Para

llel

oper

atio

n

Off

shor

e G

rid-

form

ing

& C

IO

Chopper

FilterArray cable

DG

Auxiliaries+

Controller


(WT)

DG

DGBackup

Filter Filter

Offshore Wind Power Plant

(OWPP)Diesel generator

backup


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PROMOTioN WP3 ◦ WTG – Converter Interaction Supply of Auxiliaries and Step Load Changes Wind turbine rotor side response

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WT house-load (aux) 3-5% 20% step P load

Impact on loads to be investigated!

Torque


PROMOTioN WP3 ◦ WTG – Converter Interaction

Ongoing: Black start simulation test on part of DK2

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Outside PROMOTioN Energinet performs Black Start field test with Skagerrak 4 (SK4) HVDC interconnector WP3 Performs Black Start Simulation Test with Offshore WPP To energize: • 3 buses • Overheadline & underground cable • Shunt reactor & transformer • Step MW++ load

• Load changes • Frequency & voltage setpoint changes • Load disconnection

SK4

[https://ens.dk/sites/ens.dk/files/Statistik/el_produktion_og_transmission_2017_300dpi.pdf]

31-10-2018


PROMOTioN WP3 ◦ WTG – Converter Interaction

Any Questions?

12 Brussels 11.10.2018

grid forming offshore wind turbines towards power system ......offshore ac network start-up options...

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