Synchronous Condensers for reliable HVDC operation and ......Consumption 900 - 2500 MW Primary power stations 2900 MW Local CHP plants 650 MW Wind turbines 1000 MW Photo voltaic 200

Synchronous Condensers for reliable HVDC operation and bulk power

transfer Hans Abildgaard, Nan Qin

Energinet.dk 15PESGM3046

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Denmark is located between a thermal- and a hydro-dominated power systems

• High interconnection capacity

• First HVDC interconnector established in 1965

• DK west – 6 LCC poles (2300 MW)

– 1 VSC pole (700 MW)

• DK East – 2 LCCs (1200 MW)

Oplægsholder

Præsentationsnoter

NAQ1: Kontiskan 1 in 1965. NAQ2: This page emphasizes many HVDC links in Danish power system. Norway 99% hydro. Sweden 50% Hydro + 50% nuclear. Germany thermal. NAQ3: Ramping rate at western Denmark. Nordic, max. 600MW/hour between two price zones and max. 30MW/minute on Konti-Skan and Skagerrak, respectively. NAQ4: UCTE requires entire regulation must be completed with +/- 5 minutes at hour shifts.

Consumption 900 - 2500 MW

Primary power stations 2900 MW

Local CHP plants 650 MW

Wind turbines 1000 MW

Photo voltaic 200 MW

Dato - Dok.nr. 4

Danish Power system 2015 Two synchronous areas

Consumption 1400 - 3500 MW

Primary power stations 2250 MW

Local CHP plants 2000 MW

Wind turbines 3700 MW

Photo voltaic 450 MW

West:

East:

excl. Bornholm, mothballed and blackstart units

1632 MW

680/740 MW

600 MW 1500/1780 MW

1300/1700 MW

import / export [MW]

600 MW

AC

DC

Oplægsholder

Præsentationsnoter

DK1 6 LCC poles (2300 MW); DK2 2 LCCs (1200 MW)

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Energinet.dk

Wind power is still increasing

Oplægsholder

Præsentationsnoter

2020 50 % of annual electric energy covered by wind power. The development will primarily take place offshore shore. NAQ1. 39% by 2014 corresponding to highest production 4455MW of installed capacity 5500 MW. NAQ2. New offshore wind power + near shore in 6 areas to achieve 50% by 2020.

Must-run is costly 7

0

10

20

30

40

50

2006 2007 2008 2009 2010 2011 2012 2013 2014

M€ DK2

DK1

Oplægsholder

Præsentationsnoter

Varies from year to year depending on market prices (hydro power). Must run is ordered from base-load units. They have to operate the entire plant in order to bring the generator on-line (5). District heating demand has ensured operation of the power stations. Thermal storage, electrical boilers and heat pumps are now being fitted to the district heating system meaing that thermal generation will be more decoupled from the heat demand. NAQ1. Decoupling heat demand from the central power plants will even force them out of market.

Why must-run?

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• Short circuit power – voltage step changes after shunt

switching – hvdc load rejection

• Dynamic voltage control – commutation of HVDC LCC – reactive power consumption from old

wind turbines • Continuous voltage control

– hvdc ramping – high voltages during low load (steady

state) (Active power reserves are bought in separate markets and do not give rise to must-run)

Oplægsholder

Præsentationsnoter

NAQ1: Load rejection potential over voltage RPC for switching off filters Smooth regulations short-circuit power NAQ2: Commutation of LCC-HVDC The reactive power absorbed is at least 0.5 MVAr/MW under ideal conditions. NAQ3: Voltage profiles for the entire system as the transits change.

Dynamic voltage control 10

Type 1 (SCIG) 59%

Type 2 (VRIG)

8%

Type 3 (DFIG) 13%

Type 4 (FCG) 20%

Onshore capacity per technology

Simulated fault recovery without and with wind power in case of insufficient dynamic voltage support.

Oplægsholder

Præsentationsnoter

NAQ1: Slow voltage reestablishment or/and collapse with fewer central power plants in some cases.

Minimise risk of commutation failures propagation

• On August 23, 2009 a successful reclosing on a 132 kV in the Southern part of Sweden caused a commutation failure on Kontek and Konti-Skan 1+2 (inverter).

• The current drawn by the rectifier end of the two Konti-Skan poles lead to commutation failure on Skagerrak 3 in Denmark

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Oplægsholder

Præsentationsnoter

NAQ1: How many central power plants in DK1 and DK2 systems? NAQ2: Is there voltage dip in DK2, especially at BJS400?? NAQ3: Is there any commutation failure at KS12? NAQ4: Is it mean the KS12 block and then restore after reclosing in Sweden that introduces a large voltage dip at TJE400?

Synchronous condensers in Denmark

Station Area PCC kV

Sn MVA

Year

Vr. Hassing DK1 150 100 1965/2013 Tjele DK1 150 160 1976/2012 Bjæverskov DK2 400 270 2013 Herslev DK2 400 200 2014 Fraugde DK1 400 200 2014

Kyndbyværket DK2 132 330 1976/199x Enstedværket DK1 150 880 1979/2013

Dato - Dok.nr. 13

Oplægsholder

Præsentationsnoter

Purple: TSO owned Green: Privately owned

Location of new SynCons

Dato - Dok.nr. 14

Main data of the new SynCons BJS (2013) FGD/HKS (2014)

Generator data 270MVA, 15.75kV±5% 200MVA, 15.75±10%

Cooling DAC TEWAC

Circuit Breakers HV HV+LV

Start-up time 15..20 min 10-15 min

GSU data 2W, uSC~14%, 420/15.75kV 3W, uSC~10%, 400/15.75kV

GSU energization Together with generator From 400kV side

GSU tap changer On-load ±10 steps of 1.25% None

SSC’’_HV, guaranteed >800 MVA >1000 MVA

QHV, guaranteed -150/215 Mvar -120/180 Mvar

Auxillary power Redundant from local 10kV From GSU tertiary winding

Breaking/stopping Regenerative+HV-brake Regenerative

AVR controlling node 400 kV 16 kV

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Oplægsholder

Præsentationsnoter

GSU Generator Step-Up transformer, stat-up time less than 15 min allows the unit to stay as a standby reserve ready for start-up. All three machines are identical. However, the new machines optimised for short circuit power with reactive power as second priority. NAQ1: Minor question, full name of DAC and TEWAC cooling system. NAQ2: What are the expected operational hours per year?

New SynCons - Purpose and requirements

• To significantly reduce the number and duration of ”must-run” requests for conventional thermal power stations, i.e. significant savings. – Short circuit level contribution – Dynamic and continuous voltage regulation – Fault-ride-through capability

• High level of availability and reliability – Well proven equipment – Redundant auxiliary systems – Detailed design reviews – Test and verification

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Inertia - currently not an issue

• In interconnected operation, the system inertia is currently sufficient – Redefinition of primary control response could be

necessary.

• The inertia provided by the new SynCons is one third of a typical steam unit. – If required additional rotating mass can be fitted to an

external flange.

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Summary and outlook • The market share for the conventional generation in

the energy market continues to fall leading to mothballing and decommissioning

• The necessary system support is built into the grid – A level playing field in the energy market – Lower socio economic costs – Maintain high security of supply

• Need for must-run will gradually decline over the next ten years – Decommissioning of Type 1 wind turbines – Commissioning of new VSC connections

(COBRAcable, Kriegers Flak DK-GE, Viking Link)

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UK NL GE

Oplægsholder

Præsentationsnoter

NAQ1: Feed-in tariff is reduced for future wind farms e.g. Horns Rev 3.

Thank you for your attention!

Hans Abildgaard Chief Engineer [email protected]

Nan Qin PhD-student [email protected]

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Documents

Synchronous Condensers for reliable HVDC operation and ......Consumption 900 - 2500 MW Primary power stations 2900 MW Local CHP plants 650 MW Wind turbines 1000 MW Photo voltaic 200