black start from vsc hvdc and its impact on ac ......2020/02/13 · projects coordination of ac...

© 2019 Electric Power Research Institute, Inc. All rights reserved.w w w . e p r i . c o m1

Black Start from VSC HVDC and its

impact on AC Protection Coordination

13th February 2020

Webcast

Oluwole Daniel Adeuyi &

Benjamin Marshall

The National HVDC Centre.

http://www.epri.com/


❑ The National HVDC Centre is an Ofgem funded

simulation and training facility available to support all

GB HVDC schemes.

The National HVDC Centre is part of Scottish & Southern Electricity Networks and is f unded through the Electricity Network Innov ation Competition as the Multi-Terminal Test Env ironment (MTTE) Project. Scottish and Southern

Electricity Networks is a trading name of Scottish Hy dro Electric Transmission plc, Registered in Scotland No. SC213461, hav ing its Registered Off ice at Inv eralmond House, 200 Dunkeld Road, Perth, PH1 3AQ; and is a member of

the SSE Group www.ssen.co.uk

part of

together with

Caithness Moray Shetland

HVDC Replicas Control Hardware

PROMOTioN IEDs

Protection Relays

❑ Using state-of-the-art simulators combined with

specialist capabilities, we model and resolve

potential issues in real-time before they impact

delivery of HVDC projects or the Grid Network.

The National HVDC Centre


http://www.ssen.co.uk/

http://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiF3vntw6nVAhXEUlAKHb3KCZgQjRwIBw&url=http://www.elp.com/articles/2016/07/judge-wants-national-grid-to-keep-power-on-for-sick-disabled.html&psig=AFQjCNGVkKSF2hcKDD7GCtA39g2w8F6Exw&ust=1501247219412142

Page: 3

Change in GB Electricity Generation Mix

Source: Ofgem Data Portal – Wholesale Energy Market Indicator

❑ GB Electricity Generation Mix by quarter & fuel source [2006 – 2019]

The transition to a net zero economy is driving changes in the GB electricity system.

https://www.ofgem.gov.uk/data-portal/wholesale-market-indicators#thumbchart-c6009892667643726-n98510

Page: 4

Consequence of Change in GB Generation Mix

❑ 17GW conventional synchronous

generation capacity replaced by

31GW low-carbon non-synchronous

technologies from 2012 to 2018.

❑ Conventional coal & gas power

stations typically can Black Start

(re-start) the grid in the unlikely

event of shutdown.

❑ However, declining levels of

conventional generation could

increase risk of system operation,

and Black Start restoration. Source: Image. Unknown Author is licensed under CC BY-SA ; Chart: based on National Grid ESO Future Energy Scenarios

2012 2018

https://creativecommons.org/licenses/by-sa/3.0/

Page: 5

Current HVDC in GB7 HVDC Links - Totalling: 8 GW

2

3

1

4

Future HVDC in GB Up to 34 HVDC Links - Totalling: 45.45 GW

Source: National Grid Interconnector Register 01 08 2019

2018

6

7

5

2019

9

12

13

15

8

17

16

21

20

14

18

22

24

25

31

32

33

34

19

29

35

2026

10

11

23

26

27

28

30

2027+

Interconnectors:1) Cross Channel (IFA)2) Moyle3) Bri tNed4) EWIC

New Interconnector:5) Nemo

New Embedded Links:6) Caithness – Moray7) Western Link

New Island Links8) Shetland9) Western Isles

New Interconnectors12) ElecLink13) NSL14) Aquind15) Viking16) GreenLink17) NorthConnect18) IFA219) Fablink20) NeuConnect21) Gridlink

New Offshore Wind Connections31) Dogger Bank32) Norfolk Vanguard34) Sofia

New Embedded Links10) Eastern Link 211) Eastern Link 1

Additional Interconnectors26) Aminth27) Atlantic Super Connection28) Continental Link

Development of HVDC Connections in GB

❑ In 2019, the Scottish Government commissioned The National HVDC Centre to investigate how HVDC cancontribute to GB Black Start and restoration.

Page: 6

HVDC as part of Black Start and System Restoration

Stage 1. Review and Instruct

Stage 3. Establish Power IslandsStage 4. Create Skeletal Network

Stage 2. Start-up & Re-energize

Network

The Main Black Start Stages are:

❑ Review& Instruct

❑ Start-up & re-energise

❑ Establish Power Islands

❑Create Skeletal Network

Source: Illustration adapted from 2018 National Grid Product Roadmap - Restoration

Page: 7

Analysis of HVDC Capability across Black Start Requirements

Technical Requirements VSC LCC VSC LCC VSC (a) (b)

1. Time for HVDC to Start-up & energize part

of the network (≤ 2 hours)

Can create

AC voltage

Requires strong AC grid or sync.

compensation

During complete shutdown embedded links cannot part icipate in early stages of Black Start,

but they can contribute to later stages of restorat ion as part of the t ransmission system.

Limited by wind availability or local generation and requires an established AC network for self-start.

2. Serv ice Availability (≥90%) of Each Year > 95% > 95% Offshore >90%; and onshore >95%

3. Voltage Control Capability Available Similar to 1 Requires strong AC voltage for energizing offshore converter and HVDC circuit .

4. Frequency Control Capability I f controller is

implemented

Similar to 1 May require de-loaded operation of wind farm or battery energy storage system.

5. Supply Black Start Serv ice ≥10h Applicable Possible if other

conditions are metRequires up to 5% of rated capacity for self-start

6. Supply Auxiliary Units ≥72h Battery & diesel generation

availableBack-up battery and diesel generation available

7. Block Loading Size (≥ 20 MW) Fast active power control capability

Possible if 1 is

availablePossible if all above requirements are met

8. Reactive Power Capability (≥ 100 MVAr

Leading)

Available Requires reactive

compensationPossible if requirements for back-energizat ion of offshore converter and HVDC circuit are met.

9. Sequential Start-ups (≥ 3 attempts) Has self-start

capability

Possible if other

conditions are metPossible if st rong AC voltage is established at terminals

▪ Interconnections

GB Grid Other AC grid

▪ Embedded LinksGB Grid

▪ Offshore Wind

LinksGB Grid

Offshore Wind Farm

▪ Island LinksGB Grid

Western Isles

Island

(a)

(b)

GB GridShetland

Island

❑ VSC Interconnection is

suitable for GB Black Startand system restoration

Page: 8

Case Study of Scotland and North East England

❑ 3 existing HVDC schemes in Scotland and North-East England (Moyle, Western Link & Caithness-Moray);

❑ 4 future links are planned (NSL, NorthConnect, Eastern Links, Shetland & Western Isles); and

❑ VSC-HVDC interconnectors & links capacity can meet the required Black Start capability, if appropriate controls are implemented.

The Centre’s study on use of HVDC to restore Scotland & North-East England identifies that:

Page: 9

Specific Recommendations

❑ Early specification and design of HVDC Black Start controls;

❑ Combined testing of HVDC-led restoration with AC protection

coordination, field demonstration & control room operator training;

❑ Use of synchronous compensators to enhance HVDC Black Start

capability; and

❑ Review of definitions for Black Start technical requirements.

In consultation with industry stakeholders, the Centre’s study conclusions are linked to:

Full report and summary article available at:

o https://www.hvdccentre.com/wp-content/uploads/2019/12/HVDC-BS-001-041219-v2.0.pdf

o https://networks.online/gphsn/analysis/1001865/alternative-route-black-start

https://www.hvdccentre.com/wp-content/uploads/2019/12/HVDC-BS-001-041219-v2.0.pdf

https://networks.online/gphsn/analysis/1001865/alternative-route-black-start

Page: 10

Research Programme

Current Innovation Projects

Coordination of AC network protection during HVDC energization

Stability assessment and mitigation converter interactions

Improving Grid Code for HVDC schemes

Completed Innovation Projects

Developing Open-Source Converter Models

Stability assessment for co-located converters

Design of DC/DC Converter

2020 Innovation Projects

Complementing HVDC with synchronous condensers/ ancillary equipment

Investigation of Power Oscillation Damping Controls

Assessment of AC protection performance with HVDC

Future Potential NIC Project

Composite Testing of Transmission Solutions

Engagement

Collaboration

Research

http://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiF3vntw6nVAhXEUlAKHb3KCZgQjRwIBw&url=http://www.elp.com/articles/2016/07/judge-wants-national-grid-to-keep-power-on-for-sick-disabled.html&psig=AFQjCNGVkKSF2hcKDD7GCtA39g2w8F6Exw&ust=1501247219412142

© 2020 Electric Power Research Institute, Inc. All rights reserved.w w w . e pr i .c o m

Jonathan Ruddy, Sean Mc GuinnessEPRI Europe DAC, Dublin, Ireland

Coordination of AC network protection settings during

grid energization from HVDC schemes

Final Project Public Webinar

13th Feb 2020


https://www.linkedin.com/company/epri

https://www.facebook.com/EPRI/

https://twitter.com/EPRINews


Electric Power Research Institute

▪ Founded in 1972 as an independent, non-profit center for public interest energy and environmental research

▪ European office opened in Dublin in 2013

▪ Collaborative resource for the electricity

sector

▪ 450+ participating companies in more than 40

countries

Independent

Collaborative

Nonprofit



Motivation – Restoration Studies

New Challenges Uniqueness

▪ Necessary capability - must have

but hope to never have to deploy

▪ Rare events, (Extreme Weather,

etc.) - Hands-on experience may

be lacking

▪ Reliance on capturing all impacts

in simulation

▪ New generation mix with wind and

solar on transmission and

distribution networks

▪ Retirement of synchronous

plants and replacement with

inverter based resources

▪ Lower inertia & fault level

Need to develop new restoration paths, blackstart resources and expertise to evolve to changing grid conditions

New Resources

▪ New blackstart resources like

DER possible but HVDC has

capacity to be most effective

▪ VSC HVDC Interconnectors have

inherent controllability & specific

modes for blackstart

New Challenges Uniqueness New ResourcesNew Challenges Uniqueness



The project case study

▪ Black start priority: connect black start unit to generation ASAP to grow power islands.

▪ Power islands expanded towards generation picking up demand along path

▪ Case illustrates generic MMC HVDC link at Blyth 400 kV (where NSL will connect) energizing a path to Cruachan pumped hydro station

▪ Detailed path modeled in DIgSILENT EMT using model provided by SPEN

▪ All detailed vendor specific protection relays modeled along restoration path



Project steps

▪ Review algorithms of protection relays on the network

▪ Use PowerFactory simulations to perform restoration studies– Grid restoration from VSC HVDC with/without

faults– Transformer energization

– Cold load pickup– Controlled and uncontrolled resynchronization of

HVDC island grid to another blackstart island or other grid.

▪ Hardware testing of specific relays in HVDC Centre Lab– Study relay response to specific, triggered events



HVDC Voltage/Frequency control mode

▪ Norwegian station maintains DC link voltage

▪ Blyth HVDC station in Island control mode - Grid forming

▪ Imposes system angle and frequency from reference on AC network via AC voltage controller

▪ Once synchronous grid established and islands connected HVDC can return to grid following mode



• Network starts from dead

• Each line, transformer switched in one by one

• During restoration planning, each switching step studied for issues such as transient overvoltages, voltage-regulation, harmonic resonance, protection coordination

Traditional System

Restoration

• Can be used with VDC HVDC and (with modifications) synchronous generators

• Circuit breakers operated to isolate an area of the network with the blackstart unit

• No load or other generators connected to the area except blackstart unit

• Voltage ramped slowly from 0pu to 1pu

• For synchronous generators ramping time-frame is tens of minutes

• For VSC-HVDC ramping time-frame is seconds to minutes

Soft Energisation



Hard Energisation (traditional method)

▪ Traditional switching – set HVDC voltage to nominal & switch in each component

▪ Each switching action creates inrush currents and voltage fluctuations that the HVDC must control, damp, and ride-through

▪ Undamped resonance condition may occur if insufficient load is available early on in restoration to assist damping

▪ Resonant frequencies vary from circuit to circuit

▪ Options to mitigate:– Damping controls on HVDC

– Pick up load

– Soft Start HVDC VSC HVDC



Soft Start HVDC method

▪ Full blackstart path energized via soft start

▪ HVDC as only source

▪ Soft start ramp minimisestransients and inrush currents

▪ ~1400 MVA HVDC has plenty of capacity left to begin: – connecting more central

Scotland 400 kV, 275 kV network

– connecting load

– Synchronizing to pumped hydro and rest of grid VSC

HVDC

u = 1.02puu = 0.95 pu

P = 0.5 MW

Q = -212 Mvar



Protection Implications



What are the protection issues?

Issues to consider with inverter-dominated grids?

Some obvious issues:

• Lower short circuit level – protection sensitivity

• Much less negative sequence current – impact on impedance calculation

• Insensitivity of output power to frequency changes

Some less obvious issues:

• Fast-acting inverter controls – relay signal processing response to faster phase angle and frequency fluctuations

• What does an unstable inverter output look like?

• Relay ability to track rapidly-varying inputs



Scope of Protection Research

Document protection algorithm dynamic response

Create manufacturer-specific relay models on restoration path

Assess protection coordination and sensitivity on restoration path

Study protection response to disturbances using EMT simulations

Perform hardware-in-the-loop testing using RTDS and relays

Identify potential issues and potential mitigation methods



▪ Aim: Perform quick assessment of relay signal processing to determine if there are any obvious risks

▪ Review signal processing adopted in static and microprocessor relays

Task 1:Protection Technology

Task 2:Grid Models

Task 3: Grid Studies

Task 4:Hardware Testing

Task 5:Knowledge Transfer




Task 2:Grid Models




Examining:

• Frequency Measurement Range

• Digital Filtering

• Frequency Measurement method

• Memory voltage

• Transformer inrush detection

• Power swing detection method




Task 2:Grid Models




Dynamic

response of relay

should be

established

Impact of dc

offset, inrush,

inverter instability




Task 2:Grid Models



Task 5:Tech Transfer

Parameter Relay 1 Relay 2 Relay 3

Frequency Measurement Range

45-65 Hz 20-65 Hz 40-60 Hz

Digital filter type 48 sample/cycle, 16-bit A/D converter with anti-aliasing filter. Low-pass filter used with Fourier signal processingFrequency-tracking used with phasor calculation

64 samples/cycle with FIR filter (currents) and “special” digital filter for voltagesSingle-cycle Fast Fourier Transform used to calculated phasors

DFT. Sampling rate not documented

Frequency measurement method and measurement window

1-cycle, 24 sample DFT used for phasor estimationRecursive Fourier algorithm to detect changes in

phase angle and hence frequency calculation

Estimates period from two consecutive zero-crossings after FIR. The period is used after several security conditions are met, such as true RMS

signal must be above 6% nominal for a certain time. If security conditions are not met, the last valid measurement is used for a specific time after which it reverts to nominal system frequency.

Filters and repeated measurements used to ensure that the frequency measurement is free from harmonic and phase jumps influences.

Memory Voltage Used if positive sequence voltage falls below 80% and then for a user-configurable time-span.Then actual voltage is used if it is above 10% of

rated voltage or will “assume forward fault”/”assume reverse fault” if configured

Used if positive sequence voltage falls below 80%. Used until timer expires (range 5-25 cycles), thenuses measured voltage if above 10%

Uses positive sequence voltage from previous 2-20 cycles. Last valid directional decision is retained until voltage has returned.

Incorporates measured frequency into directional calculation.

Transformer Inrush Detection Method

2nd harmonic current exceed 25% of 50Hz currentFull cross-blocking of all phase-loops and impedance zones

2nd harmonic current exceed 15% of 50 Hz currentFull cross-blocking of all phase-loops and impedance zones

2nd harmonic current exceed 15% of 50 Hz currentFull cross-blocking of all phase-loops and impedance zones

Power swing detection method

If positive sequence impedance trajectory takes longer than 5ms to pass outer to inner impedance zone blinders.

If positive sequence impedance trajectory takes a user-defined time between 0.0 seconds and 65.535 seconds to pass outer to inner impedance zone blinders.

Proprietary method based on



PowerFactory Relay Models:

• Vendor-specific relays

models used

• Captures digitalisation and

sampling: sampling rate, DFT

Above: Block diagram of GE D60 Relay model in PowerFactory showing CT and VT inputs, input processing, impedance calculation, trip logic and output commands

Input Blocks

Signal Processing

Function Blocks Logic Blocks


Task 2:Grid Models




Protection Grid



Hard Energization

▪ Inrush current magnitude limited by HVDC controller

▪ In some cases inrush current excited resonance around 7th harmonic

▪ Connecting load increased damping and mitigated resonances

▪ Other options:– Pre-insertion resistors in series with circuit breaker

– Use of air-break disconnectors when switching-out transformer

– Reducing system voltage before energizing

– Adjusting on-load tap before energization

– Injecting DC to de-magnetise the core


Task 2:Grid Models




400 kV Voltage and Current – Resonance Case

400 kV Voltage and Current – Stable Case



Soft Energization

▪ Voltage ramped over 1 second

▪ No load or wind farms inside energised area

▪ Inrush current negligible, so no observed risk of protection maloperation

Key Protection Concerns:

Undervoltage protectionUnder-impedance starter elementsSwitch-on-to-fault elements


Task 2:Grid Models






Soft Energisation with Fault: Three phase fault on 400 kV line ~200km from HVDC

▪ HVDC configured to soft-energise by ramping to 1pu voltage over 2 seconds

▪ Fault current increases from 0 to 400A (unit protection minimum operating current)

▪ Unit protection trips at t=168ms

▪ Sudden voltage recovery after breaker opens excites inrush and a resonance


Task 2:Grid Models






Resynchronization with Neighbouring Grid

▪ Neighbouring grid is high inertia

▪ Considered synchronization near and far away from HVDC

▪ With and without synchronous generators

▪ Tested different phase angle differences: 0, +/-15, +/-45

▪ Case with HVDC+synchronous generator less stable than HVDC-only

▪ Angular stability an issue due to distance from sync-point to generator and phase diff.

▪ Having load connected near generator prior to re-synch improves stability.


Task 2:Grid Models






▪Hardware in the loop testing

▪Relays and relay models configured using as-built data

▪Disturbances simulated in RTDS

▪Compare hardware and models:

– Voltage, current, phase angle

– Relay tripping elements/times

– Relay transient measurements


Task 2:Grid Models






▪ Example:

– Three-phase fault

– Note current ramps up after fault reaching steady-state after 1-2 cycles

▪ HIL relay testing matched simulated performance

▪ Further relay testing underway


Task 2:Grid Models






Conclusions and Recommendations



▪ Key Conclusions:– Risk of resonance during hard-energisation

▪ Existing protection may not trip in response to the resonances

▪ Relying on HVDC to detect and trip unless mitigation implemented

– Soft-energisation

▪ Delayed fault clearance likely

▪ Risk of exciting resonance due to fast post-fault voltage recovery

– Stability:

▪ Strategic reconnectiong of load required to maximise grid stability

– VSC-HVDC provided sufficient current for fault detection/relay operation

– Weak grid issues exist which could complicate connection of wind farms


Task 2:Grid Models






Conclusions & Recommendations

▪ Re-synchronisation of the “restored” AC grid fed by the HVDC to the rest of the AC grid is a topic which requires further research.

▪ Signal processing/filter differs between relays. Further testing underway to validate software models and transient response

▪ Future R&D focus on switching HVDC from Grid Forming to Grid Following

▪ Potential inverter instability issues when connecting wind farms into low-inertia/weak grid



Next Events▪ Paper presentation at IET DPSP on

March 12th in Liverpool

EPRI Webcast:

▪ Detailed technical discussion on system restoration from HVDC

▪ Transmission operator experience

▪ Date: April 1st,14:00-15:30 GMT

▪ Venue: WebEx (invite to follow)

Contact Details:▪ Mr. Sean McGuinness,

– Principal Technical Lead for T&D Grid Protection,

– EPRI Europe, Dublin

– E-mail: [email protected]

▪ Dr. Jonathan Ruddy,

– HVDC Researcher,

– EPRI Europe, Dublin

– E-mail: [email protected]


mailto:[email protected]



Together…Shaping the Future of Electricity


Page: 40

Questions and Answers

❑ Q1: LCC may actually part icipate in blackstart immediately after first voltage is available. Only that such LCC may not provide its full output.

❑ A1: Yes, international experience of Black Start from LCC with synchronous compensation is out lined in the full report. Visit : https://www.hvdccentre.com/wp-content/uploads/2019/12/HVDC-BS-001-041219-v2.0.pdf

❑ Q2: Was Quad characterist ics used for distance protection, which is preferred to be used as it offers better control over resist ive reach?

❑ A2: Mho characterist ic distance protection relays are used in Scotland. The work is focusing on evaluating the exist ing protect ion system performance.

Quad could be used, but the benefits are primarily for short lines. For 275 and 400 kV lines the X reach is long, so the R reach is long by default . Quad would not increase sensit ivity all that much, but would require enormous capital investment to upgrade all of the relays along the restorat ion paths.

❑ Q3: Have you explored Inert ia provision from the HVDC?

❑ A3: No – this project focussed on conventional HVDC black start which complements a st iff voltage source with fast active power ramping, but has no inert ia. As highlighted this presents a number of challenges at the point of resynchronisat ion with another power island, or when significant synchronous

generators are added to the black start island. Considerat ion of VSM based control st rategies and their effect on protection (which should provide it a more conventional form of inject ion) would be future work

❑ Q4: Was fault simulat ion performed in PowerFactory and then the recorded waveforms replayed in the RTDS for injection?

❑ A4: No – in addit ion to DigSilent PowerFactory EMT simulat ion off-line, HVDC converter with AC network was modelled using RSCAD - RTDS and interfaced with physical relays in real-t ime using power amplifiers .

❑ Q5: what protection are in place in the onshore converters of the HVDC? Can resonances be damped using the HVDC converters?

❑ A5: HVDC converter protection was modelled (dc over-voltage, over-current), but the primary focus of the analysis was AC protection response. The analysis was primarily focussed on AC protection response rather than HVDC protection, however the scenarios for which HVDC protection would be expected to triggered were considered- with it noted in certain situations for example the post fault clearance over-voltage during soft energisat ion case that the HVDC protection would need to act to protect the convertor and in other cases collapse the power island safely. Yes, the resonance during

energisat ion can be damped using the HVDC converter if damping controls are in place, designed and tuned for the resonant condit ions you expect. The challenge however is that any damping control approach is required to be flexible to a variety of energisat ion condit ions that could potentially occur during restorat ion.

Page: 41

Questions and Answers (Contd.)

❑ Q6: Is there a part icular load/generation pick-up strategy? Does the VSC-HVDC have current regulat ion during black start/grid-forming mode?

❑ A6: In ideal condit ions Local Industrial loads resist ive load or motor load would be picked up first to damp resonances otherwise occurring in the energisat ion of problematic overhead line corridors or other circuits. However this scenario cannot be guaranteed in practice- the operator will need to adapt to the resources available in the situation of the black start. A simplified HVDC model was used in Powerfactory model. HVDC converter modelled in RTDS uses inner current control loop during islanded control operation. The condit ions studied were monitored against these models encountering current

limit . Addit ional grid forming controls are the subject of other projects on virtual synchronous machines led by National Grid ESO.

❑ Q7: It appears NGESO requirements for black start are very demanding for non-conventional generators?

❑ A7: The requirements for black start are defined by NGESO in order to meet the objectives of its agreed black start strategy. In our presentat ion we have outlined the practical considerations of control and design across the stages of black start. The National HVDC centres Black Start report (see A1 above) has made a number of technical recommendations surrounding meeting these black start objectives that would support use of non-conventional

technologies such as HVDC.

❑ Q8: with soft energisat ion where there any issue with energisat ion of t ransformers?

❑ A8: In the unfaulted cases the soft energizat ion went very well with nearly no saturation of the core and small inrush current. Where the HVDC soft energised the network with a permanent fault far away from the HVDC, then after the protection trips (maybe 0.15-0.4 seconds after start of soft energizat ion) and the breakers open, the voltage suddenly recovers as the fault is no longer holding it down. That voltage jump has the same effect as hard energizat ion

result ing in inrush current. The inrush isn’t as bad as normal as the voltage might only be 0.25-0.5 pu by T=0.4s (assuming a total voltage ramp t ime of 1-2 seconds), but if can be enough to excite the resonance we saw earlier. Provided voltages are kept low for long enough during the soft energisat ion, the extent of magnetisat ion inrush may be mit igated. In addit ion to the linear voltage build up strategy which we have shown to w ork in this case study, given the size of HVDC link considered, other strategies of voltage build up over t ime can be adopted to impact from the transformers included in the soft start . These are project specific in nature based on the rat ing of the HVDC link, the circuits involved and the control flexibility of the HVDC link in delivering a

part icular voltage build-up.

❑ Q9: was overload capability on the HVDC link considered?

❑ A9:no overload capability was included- in the case study considered it was possible to deliver network energisat ion strategies without requiring an addit ional overload capability.


Thanks for listening.

Any questions, please?

❑ For further information, please visit www.hvdccentre.com ; OR email: [email protected]

❑ Register for Webcast on 27 Feb. | Stability Assessment and Mitigation of HVDC Converter Interactions (https://www.ssen.co.uk/StakeholderEvent/Registration/?EventId=474)

Follow us on Twitter @HVDC_Centre_GB

Follow our Linkedin page The National HVDC Centre for regular updates.


http://www.hvdccentre.com/


https://www.ssen.co.uk/StakeholderEvent/Registration/?EventId=474

black start from vsc hvdc and its impact on ac ......2020/02/13 · projects coordination of ac...

Documents