HVDC kraftelektronik vindkraft behov av ny kraftproduktion avdelningen elteknik på Chalmers. Ola Carlson

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1 HVDC kraftelektronik vindkraft behov av ny kraftproduktion avdelningen elteknik på Chalmers Ola Carlson

2 Clean electricity for clean environment Staff:18 senior researchers, 3 technicians & adminstrators, 29 Ph.D students Power systems and power electronics Renewable energy and grid integration Electrical machines and drives Electrical vehicle and transportation systems Study sustainable power systems consisting HVDC transmission and smart-grid based distribution for higher efficiency and flexibility Explore technologies for renewable energy generation and integration, including wind, solar, and ocean for zero-emission and stable power supply Develop high-efficiency and highperformance drive solutions to maximize energy saving and material utilization Strive for electrification of transport systems by providing innovative and cost-effective concepts, convincing demonstration, and verified knowledge Power systems (analysis, market, dynamics, stability, operation, voltage and frequency control) Power electronics in power systems (HVDC converter, AC& DC transmission, and FACTS) DC network (DC/DC converter, DC grid, and DC distribution) Smart-grid and distribution (efficient MV system, EV in distribution, and demand-side management) Wind turbine drive-train (generator, converter, transformer, and whole drive-train design) Wind power integration (connection, stability, integration) Renewable energy systems (ocean, tidal, solar, generators, converters, and grid integration) Energy storage (batteries, flywheel, storage integration, short-term storage for power stability) All-in-One drive train (deep integration of converter, motor, and mechanical parts for compact design) High efficiency machine (design, modeling, analysis, prototyping, and measurement) Converter and control (SiC, multi-level, and new topologies) Advanced testing (efficiency, noise, and environment impacts) On-board electric drivelines (motor, converter, and control) Battery (charging/discharging optimization, lifetime analysis, and integration) Electrical system operation and control on electric vehicles (HEV, EV, and PHEV) Charging (on-board devices, charging & drive integration, offroad wireless charging)

3 Master s Programme in Electric Power Engineering Year 1 Year 2 Q - I Q - II Q III Q - IV Power System Analysis Electric Drives I Compulsory High Voltage Engineering Power Electronic Converters Power System Operation Electric Drives II Elective Course High Voltage Technology Power Electronic Devices and Applications Elective Course Compulsory elective minimum 2 of 4 Main areas: Electric Drives High Voltage Engineering Q - I Q - II Q III Q - IV Sustainable Power Production and Transportation Applied Computational Electromagnetics Elective Course Power Market Management Power Electronic Solutions for Power Systems Power Engineering Design Project Elective Course Compulsory elective minimum 1 of 4 Power Electronic Power Systems Master s Thesis Work (30 ECTS credits) Compulsory

4 Other courses, NOT MPEPO Q - I Q - II Q III Q - IV Teknisk kommunikation, E1 FSP025 Miljö- och elteknik, E2 EEK136 Kandidatarbete, E3 ENMX02 Electric Drives (GM-course) LUP625 Elteknik, E3 EEK140 Sustainable Electric Power Systems, MPSES ENM125 Elektriska kretsar och elenergi, Z2 RRY135 Elanläggningsoch och reläskyddsteknik 41N09C Borås Elkraftsteknik, Lindholmen EEK565

5 National Research of Wind Power in Sweden Vindval Power companies and Industry partners Vindforsk Cold Climate SWPTC Region Västra Götaland Regional development and Environment development

6 Hosted by VÄRLDENS SKILLNAD Hosted by Chalmers University of Technology Department of Energy and Environment

7 Personnel At university: 12 senior researcher 8 PhD students 2 technicians At industry: 25 persons Other: 4 persons Total: 50 persons works within SWPTC

8 Svenskt Vindkraftstekniskt Centrum

9 On-going projects within SWPTC TG1-1 Control of turbines TG1-4 Grid code testing TG2-2 Fatigue loads in forest regions TG1-6 LIDAR system for optimisation TG2-1 Models of rotor blades TG5-1 Load- and risk-based maintenance TG5-2 Current induced damages in bearings TG1-2 Models of electrical drive TG4-2 Optimisation of blades TG6-2 Methods for deicing of blades TG3-2 Compound bearings TG3-1 Models of mechanical drive TG6-1 Sensors for detection of ice TG1-5 Measurements for verification TG4-1 Models of turbines

10 Källa EWEA

11 Wind power hosting capacity (HC) of distribution systems How much wind power, then? Main limiting factors Voltage rise Thermal overloading Should we limit the HC based on worst case analysis? 10 MVA P Load min =0.5 MW Time (hours) 10.5 Max based on worst case analysis Total installed wind power MW Maximum observed reverese power flow 9.14 MW Net(active power) Load(active power) Wind power Load (reactive power)

12 Hosting capacity: case study Capacity factor 28% 24% Discount rate 5% 5% Additional capacity(mw) Main grid 10 MVA 12 MW I 5-km-3x240/25 cable MW? P min =0.5 MW Curtailed Energy(%) 3.3% 3.8% WFO's NB/life time DNO's NB/life time With AMS 3.3% curtailment = MW Based on worst case consideration = = 10.5 MW Percentile increase = ( )/ % = 83% Amount in million 5,0 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 0,5 0,0 1% 2% 3% 4% 5% 6% 8% 9% 10% 11% 12% 13% 14% 15% Curtailed energy Additional capacity Cost of reinforcement AMS costs WFO net benefit MW

13 Styrning av reaktiv effekt och därmed spänningen i elnätet Man styr fasläget för strömmen relativt spänningen. Traditionellet: Styrs fältströmmen i en synkrongenerator I dag möjligt med frekvensomriktare Luftledning Rött = ström Gult = spänning Kabel Ström efter spänningen = Förbrukar reaktiv effekt Ström före spänningen = Producerar reaktiv effekt

14 Uno Lamm Uno Lamm föddes i Göteborg, men tog ingenjörsexamen vid Kungliga Tekniska högskolan (KTH) i Stockholm började han på Allmänna svenska elektriska aktiebolaget, Asea, där han först genomgick företagets internutbildning. Från 1929 ledde Uno Lamm ASEA:s utveckling av högspänningskvicksilverånglikriktare. Dylika klarade på den tiden bara av ungefär volt, och omvandlare för högre spänningar skulle ha praktisk nytta för överföring av stora mängder elektrisk kraft på långa avstånd. Uno Lamm erhöll 1943 doktorsexamen från KTH. Efter ungefär tjugo års utvecklingsarbete för att framställa en likriktare med tillräcklig kapacitet för högspänd likströmsöverföring, erhöll Asea 1950 en beställning för HVDC Gotland-projektet, vilket var det första moderna helt marknadsmässiga högspända likströmssystem då det stod klart 1955.

15 HVDC Det finns idag två tekniker för HVDC. Den ena, som bygger på tyristorer, kallas linjekommutering och utvecklades på talet. Den andra tekniken kallad tvångskommutering bygger på IGBT-transistorer som till skillnad mot tyristorer även medför kontrollerad släckning. Tvångskommuterade så kallade voltage source converters (VSC) utvecklades av ABB på 90-talet och har idag blivit en etablerad teknik. Större leverantörer av HVDC-teknik är ABB, Alstom och Siemens.

16 Utvecklingen av kraftelektronik Transistorn föddes 1947 Tyristorn som ventil för höga effekter 1967 (HVDC) {nätkommuterad} GTO-tyristor (släckbar) ca 80-talet {tänd och släckbar} MOSFET ca 90-talet, låga spänningar IGBT ca 90-talet, höga spänningar {utvecklingspotential} Enskild IGBT 6500 V, 600 A eller 1700 V, 3600A HVDC-Light MW Forskning på nya material, kiselkarbidtransistor => högre spänningar och strömmar samt lägre förluster Slutsats: ung teknik som utvecklas snabbt.

17 Högspänd likström, HVDC MW Långa kablar (t.ex hav) Hög verkningsgrad Utmärkt styrbarhet Dyrt med ac/dc/ac-omvandling Generator Photo: Last AC to DC DC to AC

18 HVDC Interconnections in North Europe Denmark Sweden Bjæverskov SwePol 600 MW 450 kv 1999 Germany Baltic 600 MW 450 kv 1994 Bentwisch Kontec 600 MW 400 kv 1995

19 Introduction 1. Background. Why HVDC? HVDC Transmission features Transmission of large amount of power over long overhead lines For crossing long submarine distances, which is not possible by AC technology Asynchronous link between AC systems where AC ties are not feasible Control over the power exchanged between two areas Flexibility of HVDC enables improvement of performance of the overall AC/DC system HVDC enables transmission of more power with less Right of Way (ROW), less reactive power compensation (Same power being transmitted)

20 Why VSC (Voltage Source Converter) HVDC (ABB=HVDC Light) Particular advantages with VSC HVDC 1. Voltage source functionality U v U v Rapid, independent control amplitude of active and reactive power adjustable phase angle No need for a strong grid

21 Introduction 1. Why VSC HVDC Particular advantages of VSC HVDC 2. Power direction reversal through DC current reversal P 3 + U d - I d 3 Lightweight, less expensive, extruded polymer DC cables can be used

22 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

23 ABB:s största order någonsin HVDC till vindfarm i Nordsjön 900 MW 135 km i sjön & land Fyra år från order till drift (normalt för luftledning 7-10 år)

24 Diode rectifier Thyristor converter Diodes AC/DC-rectifier Thyristors AC/DC-rectifier or DC/AC- Inverter Used together with synchronous generators Idc + Uac - Iac + Spole Udc - Trefas växelspänning effektriktning Likström U ac Iac U dc Idc

25 Passive rectifier operation + To load 0-6-pulse Graetz rectifier bridge From load

26 Passive rectifier operation + To load 0-6-pulse Graetz rectifier bridge From load

27 Passive rectifier operation To load pulse Graetz rectifier bridge From load

28 Passive rectifier operation - To load pulse Graetz rectifier bridge From load

29 Passive rectifier operation - To load pulse Graetz rectifier bridge From load

30 Passive rectifier operation To load pulse Graetz rectifier bridge From load

31 Thyristor equipped rectifier Phase Angle operation To load 0 Star winding 6-pulse Graetz rectifier bridge From load

32 Thyristor equipped rectifier Phase Angle increased Reduced Power operation To load 0 Star winding 6-pulse Graetz rectifier bridge From load

33 From dc- to ac-voltage

34 Tre fas växelriktare Matning Likriktare oftast elnät med 1 eller 3 faser Last t.ex. asynkronmotor Zlast Z last lastens nolla Z last

35 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 Typical applications: high-power converters operating at medium or high voltage. 1 2 levels levels levels levels

36 Jämförelse HVDC-light och multinivåomriktare

37 Wind power with variable speed Way use variable speed? mechanical + + Less noise structural constitution electric + Less power pulsations + Possible to connect to a weak grid More expensive electric system About the same efficiency

38 Torque measurements with constant and variabel speed Measurements from Chalmers test wind turbine 1986 Constant speed Variabel speed Nm 175 Nm tid (s) tid (s) Large torque rippel High mechanical forces Long lifetime of gearbox Small influence on power quality

39 Full Power Converter Full control of P & Q All power trough the converter Higher losses Generator AG, SG, PM t (s) Inkoppling med variabelt varvtal och bladvinkelreglering Chalmers 1984, industrin 1990 P (kw) Q (kvar)

40 Grid code testing by VSC-HVDC General Electric design and install, Göteborg Energi operate: Chalmers cooperation: Validation of models for mechanical and electrical systems Develop and carry out Grid code tests of the wind turbine 4 MW General Electric 8 MW HVDC-light converter

41 GE 4.1/113 Installation winter 2012/13

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43 HVDC Göteborg Lokalisering - Risholmen HVDC GE 4.1MW

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46 HVDC Göteborg System Anslutande elnät HVDC Vindkraftverk GE 4.1 MW HVDC

47 Möjligheter med 8 MW HVDC i Göteborg Unik anläggning med HVDC som är tillgänglig för forskare och industri En del i Smart Lab på Chalmers/i Göteborg Möjligt att testa alla delar av Grid Codes Kan simulera alla typer av elnät för undersökning av nätintegration av vind- och solkraft Testning av multilevel omriktarmoduler Möjlighet till att skapa forskningssamarbete inom landet, inom Norden och Europa

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49 Low Voltage Ride Through Fault representation at the connection point Example: System Voltage [pu] E.ON (Germany) [6] National Grid (U.K.) [7] Red Eléctrica España (Spain) [8] EirGrid (Ireland) [9] Energnet.dk (Denmark) [10] Svenska Krafnät (Sweden) [11] Nordel [12] Time [s] Different requirements for active and reactive power.

50 Conventional Method of Grid Code Test Impedance-based testing device

51 VSC-Based Test Method of Grid Code Overview of simulation setup and system modeling Wind Turbine Test Equipment: VSC in back-to-back Wind Turbine Generator G Coupling Inductor and Filters Full Power Converter AC DC DC AC Coupling Inductor and Filters Output Transfomer PCC Coupling Inductor and Filters Grid Code Testing AC DC DC AC Coupling Inductor and Filters AC Grid LVRT profile Voltage dip V/Vn 1.0 V/Vn 1.0 t [s] t [s] 4 MW Full Power Converter WT 8 MW Converter as Test Eq.

52 Danish LVRT test LVRT profile 0.50 VSC1 out Time [s] Time [s] Voltage [pu] Voltage [pu] Danish LVRT Controled PCC voltage VSC1 out 2 (a) Time [s] (c) WT Output Power [pu] It1 ABC Time [s] Current [pu] Active Power Test VSC terminal current LVRT TEST. (a) Danish grid code, (b) WT output power, (c) Controlled PCC voltage, and (d) test equipment terminal current. (b) (d) Reactive Power

53 Upcoming Activities Laboratory setup at 100 kw / 400 V. Simulation and testing of unbalanced LVRT test.. To study control interaction between HVDC and wind turbine Field test

54 Copyright 2003 by John Wiley & Sons, Inc. Europe 20XX 99LFC0825 Hydropower Solar Energy Windpower DC cable transmission

55 Wind farms connections

56 Connection of wind farm DC-grid to other countries or wind farms HVDC-connection AC-connection high voltage

57 AC based wind farm Used in todays wind farms local wind turbine grid WT WT WT WT WT WT WT WT offshore platform transmission system wind farm grid interface PCC WT WT WT WT WT WT WT WT collecting point

58 AC/DC wind farm AC grid with HVDC transmission local wind turbine grid WT WT WT WT WT WT WT WT WT WT WT WT offshore platform AC DC transmission system wind farm grid interface DC AC PCC WT WT WT WT collecting point

59 local wind turbine grid WT WT WT WT WT WT WT WT WT WT WT WT WT WT WT WT DC based wind farm DC grid with HVDC transmission DC DC DC DC DC DC DC DC offshore platform DC DC collecting point transmission system wind farm grid interface DC AC PCC

60 The DC-based wind farm Internal DC bus connecting the turbines DC/DC converters to increase the voltage levels Lower weight for the transformer and longer cable distances possible High frequency transformer

61 Design of the fullbridge converter Choice of switching frequency A trade off between low weight and low losses Total converter losses [%] Weight Losses Switching frequency [Hz] Weight of the transformer [ton] - 1 khz is a suitable switching frequency. - Weight of 1 khz transformer is ~10% of the weight of a 50 Hz transformer. - METGLAS core.

62 Building the DC grids in steps HVDC Grid Feasibility Study, CIGRE Working Group B4-52

63 Operation and control-base Case Base case, P_WPP=0pu P 3 = 3 120km 100km 145km 5 P 5 90km = = = 80km = P 1 P 2 = P 6 P2_WPP=0pu P5_WPP=0pu Base Branch Power [pu] Time series branch power P km Time [hour] Branch-1->2 Branch-2->3 Branch-2->4 Branch-3->4 Branch-4->5 Branch-5->6

64 Operation and control-uncontrolled Base case, P_WPP=0.35pu P 3 P 4 = 100km 5 P 5 90km = = km 145km = 80km = 180km P 1 P 2 = P 6 P2_WPP=0.35pu P5_WPP=0.35pu Uncontrolled Branch Power [pu] Time series branch power Branch-1->2 Branch-2->3 Branch-2->4 Branch-3->4 Branch-4->5 Branch-5-> Time [hour] How can we control this? Over loaded lines, this happens up to 12% of the time during a year on some lines

65 Operation and control Primary control Droop control (primary control) P ref U ref U P - 1/m + = - Controlled Branch Power [pu] Time series branch power Branch-1->2 Branch-2->3 Branch-2->4 Branch-3->4 Branch-4->5 Branch-5->6 Over loaded lines, this happens up to 9% of the time during a year on some lines Time [hour] Primary control alone does not ensure keeping the branch power flows within the limiting values The need for a supervisory or secondary control

66 Pbus Operation and control Secondary Control Supervisory (secondary control) CCU= Central Control Unit Pbus Pbus_ref UDC_ref YES Is {[Pbranch] > [P(cable rating)]} U DC _ ref = P bus_ref U DC UDC Pbranach P(cable ratings) NO P bus Pbranch P branch CCU + - ΔPbranch M ΔP bus - Converssion matrix HVDC GRID P bus PS Model (Network model) + = UDC Pbranach P bus_ref U DC_ref UDC_ref Pbus_ref Pbus Controlled Branch Power [pu] Time series branch power Branch-1->2 Branch-2->3 Branch-2->4 Branch-3->4 Branch-4->5 Branch-5-> Time [hour] Pbranach UDC UDC Pbranach = Pbus Pbus_ref = UDC_ref UDC_ref Pbus_ref

67 Olas vision Try to start a demonstration set-up of the three part connection in Göteborg

68 Future? In operation outside Portugal