TSFS11 HVDC. Lecture 13 Tomas Jonsson ISY/EKS

Transcription

1 TSFS11 HVDC Lecture 13 Tomas Jonsson ISY/EKS

2 Outline HVDC Introduction Classic HVDC Basic principles VSC HVDC Basic principles VSC in the power grid - Wind applications

3 HVDC Introduction High Voltage Direct Current

4 Tackling society s challenges on path to low-carbon era means helping utilities do more using less 30,000 Terawatt-hours (TWh) 20,000 10,000 Forecast rise in electricity consumption by 2030 Source: IEA, World Energy Outlook ,500 12,500 20, % 29,000 Others NAM Europe India China Solutions are needed for: Rising demand for electricity more generation Increasing energy efficiency - improving capacity of existing network Reducing CO 2 emissions Introduce high level of renewable integration Meeting the rise in demand will mean adding a 1 GW power plant and all related infrastructure every week for the next 20 years

5 The evolution of grids: Connect remote renewables Europe & Germany are planning large scale VSC-HVDC Source: DG Energy, European Commission European Visions Hydro power & pump storage -Scandinavia >50 GW wind power in North Sea and Baltic Sea Hydro power & pump storage plants - Alps Solar power in S.Europe, N.Africa & Middle East Germany (draft grid master plan) Alternatives to nuclear-distributed generation Role of offshore wind / other renewables Political commitment Investment demand and conditions Need to strengthen existing grid ABB Group May 21, 2018 Slide 5

6 What is an HVDC Transmission System? HVDC Converter Station > 6400 MW, Classic Overhead Lines Two conductors HVDC Converter Station > 6400 MW, Classic Hydro AC-Grid Alt. Submarine cables AC-Grid Solar Solar AC-Grid HVDC Converter Station < 1200 MW, Light Land or Submarine cables HVDC Converter Station < 1200 MW, Light AC-Grid Power/Energy direction

7 Why HVDC is ideal for long distance transmission? Capacitance and Inductance of the power line ABB Group In cable > 50 km, most of AC current is needed to charge and discharge the C (capacitance) of the cable May 21, 2018 Slide 7 Transmission Capacity [MW] G I = I 0 - I C U I 0 0 load G C Cable I C = ωcu 0 U L = ωli 0 U=U 0 -U L In overhead lines > 200 km, most of AC voltage is needed to overcome the L (inductance) of the line C& L can be compensated by reactors/capacitors or FACTS or by use of DC, which means ω = 2πν = 0 AC 500 kv DC ±320 kv AC 345 kv AC 230 kv Length of Cable [km] Transmission Capacity [MW] Overhead Line HVAC L HVDC load Length of Transmission Line [km] 800 kv 500 kv 765 kv 500 kv

8 Investment cost versus distance for HVAC and HVDC Investment Costs Critical Distance Total AC cost Total DC Cost DC terminal Costs AC Terminal costs Variables - Cost of Land - Cost of Materials - Cost of Labour - Time to Market - Permissions - etc. Distance

9 ABB Group May 21, 2018 Slide 9 More than 50 years ago ABB broke the AC/DC barrier Gotland 20 MW subsea link 1954

10 ABB has more than half of the 145 HVDC projects The track record of a global leader Nelson River 2 CU-project Vancouver Island Pole 1 Rapid City Square Butte Pacific Intertie Pacific Intertie Upgrading Pacific Intertie Expansion Intermountain IPP Upgrade Blackwater Highgate 58 HVDC Classic Projects since HVDC upgrades since HVDC Light Projects since 1997 Châteauguay Outaouais Quebec- New England EWIC English Channel Dürnrohr Sardinia-Italy Sapei Cross Sound Mackinac Eagle Pass Sharyland Rio Madeira Itaipu Inga-Shaba Caprivi Link Hällsjön Troll 1&2 Troll 3&4 Skagerrak 1-3 Skagerrak 4 Valhall NorNed Konti-Skan Tjæreborg BorWin1 DolWin1 Dolwin 2 Apollo Upgrade Cahora Bassa Brazil-Argentina Interconnection I&II Italy-Greece Chandrapur Phadge Vizag II Rihand-Dadri Vindhyachal North East Agra FennoSkan 1&2 Estlink Gotland 1-3 Gotland Light NordBalt SwePol Baltic Cable Kontek Hülünbeir- Liaoning Lingbao II Extension Three Gorges-Changzhou Three Gorges-Shanghai Sakuma Gezhouba-Shanghai Xiangjiaba-Shanghai Jinping - Sunan Three Gorges-Guandong Leyte-Luzon Broken Hill New Zealand 1&2 Directlink Murraylink ABB Group May 21, 2018 Slide 10

11 Development of HVDC applications HVDC Classic Very long sub sea transmissions 580 km Very long overhead line transmissions Very high power transmissions HVDC Light Offshore power supply Wind power integration Underground transmission DC grids

12 HVDC Technologies Hydro HVDC Classic Current source converters Line-commutated thyristor valves Requires 50% reactive compensation Converter transformers Solar Solar Minimum short circuit capacity > 2x converter rating HVDC Light Voltage source converters Self-commutated IGBT valves Requires no reactive power compensation Standard transformers No minimum short circuit capacity, black start

13 Classic HVDC basic principles

14 AC and DC transmission principles Power Direction HVAC X ~ ~ E 1 δ E 2 0 HVDC ~ U d1 U d2 R E 1 δ E 2 0 ~ Power flow independent from system angles

15 Principles of AC/DC conversion, 6-pulse bridge Id U R IR R US IS S Ud UT IT T U RT U ST U R U S U T ωt

16 Relation between firing delay and phase displacement (a) α = 0 i a1 e a i a wt E I a a1 (b) α = 30 α I d ϕ E a I a1 (c) α = 60 α E ϕ a I a1 E a (d) α = 90 α ϕ I a1 (e) α = 120 (f) α = 150 α α E E a ϕ a ϕ I I a1 a1

17 Classic HVDC, Active vs Reactive Power How the Reactive Power Balance varies with the Direct Current for a Classic Converter... QQ 0,5 converter Shunt Banks Harmoni Harmonic Filters c 0,13 Classic converter filter filter converter filter unbalance unbalance 1,0 I unbalance d unbalance I d

18 Baltic Cable 600 MW HVDC link L36994

19 The HVDC Classic Monopolar Converter Station Converter station Transmission line or cable Converter Smoothing reactor AC bus DC filter Shunt capacitors or other reactive equipment AC filters Telecommunication ~~ Control system

20 Monopolar Converter station, 600 MW AC line AC Switchyard Converter Transformers Valve Hall DC line Shunt Capacitors Harmonic Filters Approximately 80 x 180 meters DC Switchyard

21 Longquan, China HVDC Classic

22 VSC HVDC basic principles

23 Introduction 1. Why VSC HVDC Particular advantages with VSC HVDC 1. Voltage source functionality U v U v Rapid, independent control of active and reactive power No need for a strong grid

24 Introduction 1. Why VSC HVDC Particular advantages of VSC HVDC 3. Pulse width modulation of AC voltages Small filters, both on AC and DC side

25 VSC HVDC basic principles 2. VSC converter topologies Two-level voltage source converter. Converts a DC voltage into a three-phase AC voltage by means of switching between two voltage levels. U d U d Basic operation of a phase leg: + U d + U d + U d u i u i u i - U d - U d - U d + U d - U d u i t

26 VSC HVDC basic principles 2. VSC converter topologies Multilevel topologies - basics + Phase voltages are multi-level (>2). + Pulse number and switching frequency are decoupled. + The output voltage swing is reduced less insulation stress + Series-connected semiconductors can be avoided for high voltage applications - More complicated converter topologies are required - More semiconductors required Typical applications: high-power converters operating at medium or high voltage. 1 2 levels levels levels levels

27 VSC HVDC basic principles 2. VSC converter topologies Multilevel converter topologies Neutral point clamped (NPC) topologies Flying capacitor topologies Cascaded topologies Modular Multilevel Converters (MMC) Half-bridge and full-bridge variants Module N Ud,m U d U d Module 2 Module 1 Ud,m U d U d U d Ud,m Module N Ud,m Module 2 One phase leg, or equivalent, shown in each case Module 1

28 VSC HVDC basic principles Modular multi-level converter (MMC) Modular multi-level converter (MMC) Prof. Marquardt, Univ. Munich Module N Ud,m Ud,m Ud,m DC capacitors distributed in the phase legs DC capacitors handle fundamental current Scalable with regard to the number of levels Twice the total blocking voltage required (twice no of semiconductor devices) compared to two-level converter Redundancy possible by shorting failing cells Module 2 Module 1 Ud,m Ud,m Ud,m Ud,m Ud,m Ud,m DC terminal Module N Ud,m Ud,m Ud,m Module 2 Ud,m Ud,m Ud,m Module 1 Ud,m Ud,m Ud,m AC terminal

29 VSC HVDC basic principles MMC-converter, switching principle +U d D1 T1 C I vpa I vpa L v D1 T1 C D2 T2 I v D2 T2 U cp1a U v L v I vna C D1 T1 U cp1a D2 T2 C D1 T1 D2 T2 Three operating states of the converter cell: Bypass mode. Cell capacitor is bypassed. (Green curve) Inserted mode. Cell capacitor is inserted and giving contribution to converter output voltage Blocked mode. All IGBTs non-conducting -U d

30 VSC HVDC basic principles MMC-converter, Output voltage Third harmonic modulation 300 M9 version 2.2, 320kV, M2LC, P=3.37, N=35, C=1mF, no 2nd harm Cell 200 Uv(t) [kv] n time s VSC Toolbox version Dec :22:05 n 2-1 ABB Group Slide 30 PowDoc id

31 VSC performance Switching Principle Uvalve Uvalve 2-level ±150 kv dc MMC ±320 kv dc

32 VSC performance Valve voltages and currents Iigbt1 Idiod1 Uigbt1 Udiod1 2-level Reduced losses MMC

33 HVDC Light Generation 4 Double cell , (mm) 2, ,600 Mass 3,000 kg

34 IGBT Module

35 IGBT inner structure

36 HVDC Light Generation 4 Valve arm + -

37 Typical converter layout 700 MW

38 HVDC Light Generation 4 Station layout 2 x 1000 MW ± 320 kv 150 m 220 m

39 Normal operation PCC1 154 kv Offshore station Station 1 Onshore station Station 2 PCC2 380 kv Wind Park Diele Grid Offshore main breaker Diele breaker 1. Off-shore converter in voltage and frequency control. 2. On-shore converter in dc-voltage and reactive power control. 3. Windpark power reduction, 4. Off-shore converter power (P1) drops, since acvoltage control results in power tracking 5. Instantaneous dc-power unbalance (P1-P2) < 0 dc-voltage drop 6. On-shore dc-voltage control quickly reduces power (P2) to restore nominal dc-voltage and power balance. P1 (offshore) U DC P2 (onshore) time

40 VSC in the power grid Wind applications

41 Overview Offshore HVDC wind power connectors Large Wind farms Offshore AC platform Offshore HVDC Light DC cable transmission Onshore HVDC Light Main AC network MW: ± 80 kv HVDC Light (VSC) MW: ± 150 kv HVDC Light MW:± 320 kv HVDC Light VSC technology for compact solutions. ABB with 10 years experience ( 13 references)

42 Borwin 1, Dolwin 1 & 2 Offshore Point-to-Point Why HVDC Light: Length of land and sea cable Main data Borwin 1 Dolwin 1 Dolwin 2. In operation: Power rating: 400 MW 800 MW 900 MW AC Voltage Platform: 170 kv 155 kv 155 kv Onshore 380 kv 380 kv 380 kv DC Voltage: ±150 kv ±320 kv ±320 kv DC underground cable: 2 x 75 km 2 x 75 km 2 x 45 km DC submarine cable: 2 x 125 km 2 x 90 km 2 x 90 km DOLWIN1: efficiently integrating power from offshore wind DOLWIN alpha platform loadout

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