Multivendor HVDC links supplying O&G installationsPerspectives and challenges

EC Workshop: Horizon 2050 power system and the role of HVDC technologies in a highly decentralised RES generation

Brussels, 4th February 2020

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Troll A world’s first offshore HVDC installation

• 2 * 45 MW, ± 60kV DC, HVDC Light

• 2 * 50 MW, ± 80kV DC, HVDC Light

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• Park size: 3 x 1200 MW

• WTG size: 12 MW ~ 100 off per project

• HVDC export to shore

• 3 x HVDC converters

Dogger Bank windfarm, largest European VSC -HVDC link

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Largest North Sea AC grid, with multivendor HVDC links(J oha n Sverdrup HVDC links will supply the Utsira offshore grid)

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First multivendor pa ra lle l connected HVDC systems

Challenges: • Stable operation of the interconnected

power system• Avoid negative interaction phenomena

between the 2 HVDC systems

North Sea ≈200km off the coast of Norway• HVDC Pha se 1 - 10 0 MW• HVDC Pha se 2 – 20 0 MW• Different HVDC vendors • Different HVDC technologies• 110 kV subsea AC distribution network

Norway

North Sea DC ±80 kV

AC 300 kV

AC 110 kV

PHASE 1 HVDC

AC 33 kV

Harmonic Filter

Kårstø

DC ±80 kV

AC 300 kV

PHASE 2 HVDC

Haugsneset

Harmonic Filter

PHASE 1 HVDCPHASE 2 HVDC

AC 11 kV

Johan Sverdrup PH1Johan Sverdrup PH2

AC 11 kV

Gina Krog

Edvard Grieg

AC 11 kV

Ivar Aasen

AC 110 kV

AC 110 kV

AC 33 kVAC 11 kV

AC 11 kV

Essential generator

AC 110 kV

Sle ipner

The J oha n Sverdrup project will be the first a pplica tion of two HVDC links from diffe rent ma nufa cturers supplying a n isla nded offshore AC power system in grid forming opera tion

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Phenomena of inte rest with focus on inte ra ction

Impa ct of:• offshore

genera tion (volta ge a nd frequency control)

Impa ct of: Converter controls Ha rmonic intera ctions Converter protections

Impa ct of: Loa d cha ra cteristics

to volta ge sta bility Energiza tion of

tra nsformers a nd ca bles

Loa d re jection

Impa ct of: Loa d sha ring Synchronisa tion Decoupling

Impa ct of: Offshore fa ult Onshore fa ult

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Cha llenges with J oha n Sverdrup HVDC links

• HVDC ma nufa cturers supplied the EMT bla ck-boxed converte r models for the 3rd pa rty studies• RTE-Interna tiona l is performing the pa ra lle l opera tion studies (offline studies & real time studies with the HVDC C&P replicas)• Cha llenges with verifica tion, a ccess or tuning of the control pa ra meters to resolve the inte ra ction issues

• No direct communica tion between the HVDC ma nufa ctures, due to competition a nd regula tory policies in EU• Limited excha nge of technica l informa tion is only possible through 3rd pa rties• Long a nd pa inful processes for implementa tion a nd testing of new converter control stra tegies through 3rd pa rty

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HVDC vendor A

HVDC vendor B

3rd. pa rty

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Cha llenges with the multivendor, multite rmina l HVDC configura tions• Due to confidentia lity a nd inte llectua l property right (IPR) issues, HVDC ma nufa ctures only sha re bla ck-boxed

models of the ir systems with limited a ccess to EMT model pa ra meters• No Pa rty ha s the full picture of the system:

• HVDC ma nufa cturers receive simula tion results but ca nnot reproduce the intera ctions• The 3rd Pa rty (RTEi) does not ha ve a ccess to the interna l deta ils of C&P systems to a na lyse intera ctions

• Some intera ction studies require understa nding of the inte rna l converte r control stra tegies, (simula tion results depend on the EMT model a ccura cy)

• Sma ll-signa l sta bility a nd sta te -spa ce a na lysis to de termine the converte rs control inte ra ctions ca nnot be performed with bla ck-boxed EMT models

• Difficult to a na lyse a nd tune the non-a ccessible model pa ra meters in ca se of inte ra ction phenomena

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HVDC1

HVDC2

HVDC1

HVDC2

Results obta ined with generic modelsto illustra te a dverse inte ra ctions

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HVDC2 SIEMENS REPLICA

HVDC1 ABB REPLICA

PDCS/PMS KM REPLICA

SyncRela ya nd RTDS

OPERATOR WORKSTATIONS

Ma in a dva nta ges:Vendors ha ve full a ccess to their C&P system in pa ra lle l opera tion Softwa re upda tes ca n be ea sily testedExa ct copy of C&P ha rdwa reRea l C&P softwa re

Real time lab facility to de - risk JS parallel operation

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Proposa l for open source converte r controls

Accessible

Converter C

ontrols &Param

etersP, Q

, F, V

CIGRE guide 60 4Open and accessible external control

Closed internal control

Higher-levelconverter control

Output current control

Arm - balancing control

Modulation and submodule balancing

Gate signals

Circulating currentSum capacitor

voltages

Submodule capacitor voltages

Output currentreference

Output voltage reference

Insertion indices

Circulating currentSum capacitor

Voltage

Active power

Reactive power

Frequency

Proposa l for open source outer converte r control

It should be noted tha t the protections ha ve a lso a ma jor impa ct, but not included in the proposa l.

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MTDC converte r control colla bora tion, recommenda tions from Best Pa ths

Closed internal control

Open-Source external control

Source : ISGT Europe 2019, A Proposal for Open-Source HVDC Control

• The control system ca n be split into dispa tch, sta tion, upper- leve l, a nd lower- leve l control.

• An open implementa tion of the high-leve l dispa tch a nd sta tion controls a t the system leve l ca n be performed in a common ma ster controlle r.

• Best Pa ths, multivendor experiment highlighted tha t the use of such a ma ster controlle r enha nces inte ropera bility.

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Fina l rema rks

• Once upon a time Europe ha d the lea ding position in the development of VSC-HVDC technologies• China ha s ta ken a lea ding position for multivendor multitermina l HVDC projects, due to open a nd close colla bora tion

between the ma nufa ctures, consulta nts a nd a ca demia• Colla bora tion a nd combined efforts between Europea n HVDC ma nufa ctures should be encoura ged by the EC policies

a nd regula tion, in order to overcome the obsta cles with development of multivendor, multitermina l DC systems in Europe

The European power system is in transition with large integration of converter dominated power generation, FACTS

and HVDC links. This transition pose challenges to the stable operation of the power system. Stability analysis to

avoid adverse interaction phenomena between the grid components and converters require better understanding

of the internal strategies of converter controls. New methods, tools and close collaboration between vendors,

academia and consultants are required to ensure the successful transition.

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Slide Number 1Troll A world’s first offshore HVDC installationSlide Number 3 Largest North Sea AC grid, with multivendor HVDC links�(Johan Sverdrup HVDC links will supply the Utsira offshore grid)First multivendor parallel connected HVDC systemsPhenomena of interest with focus on interactionChallenges with Johan Sverdrup HVDC links Challenges with the multivendor, multiterminal HVDC configurationsSlide Number 9Proposal for open source converter controlsMTDC converter control collaboration, recommendations from Best PathsFinal remarksSlide Number 13