Integration of offshore wind in the grid challenges and solutions

Transcription

1 1 Integration of offshore wind in the grid challenges and solutions Zhe CHEN Professor, PhD Department of Energy Technology Aalborg University, Danmark Website:

2 2 Contents General challenges of offshore wind farms Layout of offshore wind farms Electrical systems for offshore wind farms High Voltage Direct Current (HVDC) transmission systems Some other activities at dept. Energy Technology, AAU Summary and outlook.

3 General Challenges Reduce cost and increase production in both planning and operation stages Improve reliability Meet grid code requirements and support grid operation Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 3

4 4 Two PhDs at Dept. of Energy Technnology, Aalborg University PhD Hongzhi LIU, completed, September, 214 Grid Integration of Offshore Wind Farms via VSC- HVDC PhD Peng HOU, to be completed in February, 217 Offshore Wind Farm Optimization

5 5 Offshore Wind Farm Optimization PhD Peng HOU, to be completed in February, 217 Wind farm configuration Advanced Control Grid Connection HVDC transmission Systems optimization Transmission system Collection system Wind speed data, distance to shore Offshore Wind Farm Optimal Design of the electrical system Constraints Datasheet Capacity Equipments Market Optimization of electrical system Capacity algorithm Cluster Cluster Cluster WT Rectifier DC/DC WT Rectifier DC/DC DC DC/DC DC WT DC/DC WT Rectifier DC/DC Star Star

6 Wake Loss Model Jensen model 2 V =V +V ( 1-C -1)( ) w t R(x)=R +kx R R(x) Partial Wake 2 R S partial V =V -V 1-1-C w t R(x) S Multiple Wakes N_rowN_col V ij 2 V =V [1- n,m [1- ] ] i=1 j=1 V 6

7 Wake Loss Calculation Case Energy Yields Comparison of Two Cases Case I Without considering wake effect Considering wake effect Energy Yields by Matlab (GWh) Energy Yields by WAsP (GWh) Error (%) % % 8 km Case II Without considering wake effect Considering wake effect % % Sylt Validation through WAsP (Wind Atlas Analysis and Application software) the results is close to that obtained with WAsP 7

8 No Optimized wind turbine placement PSO main function Initial particle population Energy yields calculation Climatological Information k=1 Update particle position and velocity Power losses calculation Cable Database Fitness Evaluation Min{LPC} LPC calculation Fitness Function Measured wind data in the vicinity of FINO3 12 sections with 3 degree per section 5 wind speed interval in each section (5m/s) Stop criteria k>iteration Yes Optimal dx, dy and LPC PSO Algorithm The optimization procedure of finding optimal wind farm layout. 8

9 Optimized wind turbine placement Table I Layout Comparisons of Two Optimal Layouts Comparison of placement of WT for three layouts. Name Power Losses Energy Yields Cable Costs LPC Layout Optimal layout for constant dx and dy Sparse optimal layout 7D layout GWh GWh 75.67GWh GWh 18.5 MDKK DKK/MWh 4.49km*18.5 1km GWh MDKK 46.2 DKK/MWh 4.74km*18. 31km GWh MDKK DKK/MWh 8.73km*11. 23km 9

10 Substation Placement (1) OS location is an important factor of designing a cost-effective wind farm. The cable connection layout design considering the number of OSs. Heuristic algorithm will be used for cable connection layout design. The energy yields as well as power losses along the cables will be taken into consideration to evaluate the layout performance. 1

11 Substation Placement (2) Table I Specification of regular shaped wind farm Total cable length for CS (km) Scenari o I Scenario II Scenari o III Scenario IV Scenario I Scenario II Trenching length for CS (km) Scenario III Scenario IV Wind farm layout comparison for regular shape wind farm Cable to shore (km) Cable costs for CS (MDKK) Cable costs for TS (MDKK) Total Cable invest (MDKK) Substation location (2.84,-5) (2.84,-5) (2.84,2.2 1) (2.84,1.38) 11

12 Optimization of Cable Connection Layout (1) Dynamic MST (DMST) algorithm to generate the cable connection layout. Cable current carrying limit is the main constraint. Uncrossed cable connection layout is desired. Minimized the levelised production cost (LPC) of the wind farm. 12

13 Voltage level Type Case Study (I) Table I: Specification of Cable Color Collection system 33kV AC Color blue green purple yellow black 7,95, 12,15 Optimization of Cable Connection Layout (2) 185,24, 3 4,5 63,8 1 Table II: Layout Comparisons for Irregular Shaped Wind Farm MST DMST Cable invest (MDKK) Total cable length for CS (km) Trenching length for CS (km) one cable two cables three cables four cables (a) one cable two cables three cables four cables (b) The illustration of cable connection configuration for case I. (a) Optimized cable connection layout using MST. (b) Optimized cable connection layout using DMST. 13

14 14 Optimization of Cable Connection Layout (3) Case Study (II) 1 one cable two cables three cables four cables (a) one cable two cables three cables four cables illustration of cable connection configuration for case II. (a)optimized cable connection layout using MST. (b)optimized cable connection layout using DMST. Table III: Layout Comparisons for Extremely Irregular Shaped Wind Farm Cable invest (MDKK) Total cable length for CS (km) Trenching length for CS (km) MST (b) DMST

15 Grid Integration of Offshore Wind Farms PhD Hongzhi LIU, completed, September, 214 Offshore VSC VSC-HVDC Link Onshore VSC DC Cable Offshore Wind Farm Dynamic Stability Study Main AC System Impact investigation Stability enhancement of main AC system 15

16 16 Impact on Power System Stability Test Power System Steady state voltage profile Dynamic voltage stability Bus1 Transient angle stability PCC

17 Voltage magnitude [p.u.] 17 Impact on Power System Stability Steady State Voltage Profile Mode 1 - Unity power factor wind power supply X: Y:.95 PCC in mode 1 Bus1 in mode 2 X: 16 Y:.95.9 Mode 2 - Rated PCC voltage wind power supply Wind power injection [MW] The wind power penetration level (WPPL) is defined as the maximum wind power injection with which the connection node voltage reaches.95 pu.

18 P of onshore VSC (MW) Q of onshore VSC (MVar) Q (Mvar) P (MW) PCC voltage (pu) Bus1 voltage (pu) Bus1 voltage (pu) PCC voltage (pu) Bus1 voltage (pu) 18 Impact on Power System Stability Dynamic Voltage Stability (a) us1 27 MW 45 MW (a) 3 27 MW MW MW 27 MW 45 MW (a) PCC (b) Time (s).4.2 MW 27 MW 45 MW (b) Time (s)

19 L4-1 CCT (s) 19 Impact on Power System Stability Transient Angle Stability L2-1 L L3.4.3 MW.2 27MW.1 45MW L1-1 near Bus6 L2-1 near Bus7 L3 near Bus9 L4-1 near Bus1 Fault location

20 Coordinated Frequency Regulation 2 Wind Turbine Ancillary Control df dt f P R 2H Pm Pe df dt f K inertia Inertia controller 1/R P inertia P droop P under Active Power Increase Droop controller Under-frequency Controller (f meas <49.8Hz) f meas 1 1 st df dt Kinertia f nom P inertia - P - + f 1 droop 1 R + 1 st gen P P _ ref P under + * P g +

21 Current limiter 21 Coordinated Frequency Regulation VSC-HVDC Ancillary Control Offshore wind farm Offshore VSC Onshore VSC Onshore AC Grid Offshore wind farm Offshore VSC Onshore VSC Onshore AC Grid ±15kV ±15kV Ancillary DC voltage controller.1 pu V wf - PI + - * V wf * i + i PI P m f grid + - f nom K f 1 st f -.1 pu v dc * v dcf + - * v dc - PI i max * i d + - i d PI P md f wf - + f grid PI Frequency signaling F v grid + - * v grid PI Normal Fault * i q + - i q PI P mq Offshore VSC control Onshore VSC control

22 Application of BESS Electric energy time-shift Load following Area regulation Wind power integration enhancement Power quality Reserve capacity Transmission congestion relief PWM converter AC grid V = Vbatt Battery model DC Pmd Pmq Ibatt Current controller P,V * i d lim * i qlim V f PWF Frequency controller Smoothing controller Pref PV controller * i d * i q Charge controller SOC Power management unit 22

23 23 Application of BESS Power Management S1 S2 S3 Reserve for frequency regulation Frequency control Reserve for wind power smoothing Smoothing control Scenario S1 S2 S3 Description Small frequency disturbance & small wind power fluctuation Small frequency disturbance & large wind power fluctuation Large frequency disturbance & small/large wind power fluctuation

24 Application of BESS Power Management Unit P WF + P WFC 1 1 st f P WF _ exp+ - Podr P o max BESS Pbatt + f meas P o max Principle of smoothing controller P f max f - nom + f 1 Pfref droop P odr P Po max 1 P f fref max 1 1 P odr Frequency controller P f min 24

25 25 Publications so far from the two PhD projects Journal papers Conference publications 7 1

26 Research in Wind Power Systems Pitch Control/Stress Reduction Wind turbine moniting and fault detection Optimal Design of Generators Power Electronics Interface Wind Turbine Control Wind Farm Design and Control Wind Power Integrationand Interaction with Grid Power System Stability and Economics with Large Scale Wind Farms Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 26

27 Smart Energy Systems Wind power station Power Station dspace System Input/Output Power Electronics-Based DG Interface Input/Output Input/Output Closed Loop Testing of Microgrids dspace System Input/Output RTDS Closed Loop Testing of Control Sytems Network Connection Computer Running RSCAD Closed Loop Testing of Protective Relay Systems p(t) variable p(t) variable p(t) fixed Wind Solar Hydro Storage Gas tanks Energy storage production energy storage Power system infrastructure Load centre Natural gas infrastructure District heating/cooling infrastructure P2G Heat pump CHP energy conversion end-users Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 27

28 Power loss distribution of generator-side converters (W) Power loss distribution of grid-side converter (W) 28 Power Electronics and its Control Power electronic interface for wind turbines Optimized design of power electronic system Wind turbine control with Power electronics Modelling and simulation Dn S4 S3 S2 On-state loss of IGBT Switching loss of IGBT On-state loss of FRD Recovery loss of FRD 2L 3L-NPC 3L-FLC Generator-side power loss distribution S Dn S4 S3 S2 S1 On-state loss of IGBT Switching loss of IGBT On-state loss of FRD Recovery loss of FRD 2L 3L-NPC 3L-FLC Grid-side power loss distribution Gearbox Induction generator R m Lm L f C f R damp Vdc Back-to-back converter C f L f Transformer R damp 3 Grid R X AC Wind turbine

29 29 Wind Farm Optimal Control V P mec Gear Box loss P Stator loss P Rotor DFIG loss P RSC Ps Pg loss P GSC Qs Qg Pout Transformer Filter Qref Pr Q r T 1 D 2 T 1 D2 loss P filter C T 2 D 1 Rotor Side Converter T 2 D 1 Grid Side Converter P P P P P P P loss loss loss loss loss out mec Rotor Stator RSC GSC filter

30 3 HVDC system and DC/DC converters i dc arm1 arm3 arm5 u cau_1 Cell11 + SMua_1 u cbu_1 Cell31 + SMub_1 u ccu_1 Cell51 + SMuc_1 u cau_2 Cell12 u ua u SMua_2 cbu_2 Cell32 u u SMub_2 ub ccu_2 Cell52 SMuc_2 u uc u cau_n Cell1n SMua_n - u cbu_n Cell3n SMub_n - u ccu_n Cell5n SMuc_n - i ua i ub i uc L s L s L s V dc a i a b i b c i c L f R f e a e b e c o L s L s L s u cal_1 Cell21 i la SMla_1 + u cbl_1 Cell41 i lb SMlb_1 + u ccl_1 Cell61 i lc SMlc_1 + u cal_2 Cell22 SMla_2 u la u cbl_2 Cell42 SMlb_2 u lb u ccl_2 Cell62 SMlc_2 u lc G G u cal_n Cell2n u SMla_n cbl_n - Cell4n u SMlb_n ccl_n - Cell6n arm2 arm4 arm6 SMlc_n - offshore onshore G G HVDC T Grid offshore converter onshore converter

31 Research on hybrid multi-in feed HVDC system with large scale offshore wind farms Norway AC system LCC HVDC link DC breaker1 Shunt capacitors BUS1 CB1 Tie line Load1 Grid side CB2 BUS3 Gen1 G Load2 Back to Back CB3 CB4 Gen2 G Wind Farm DC breaker2 VSC HVDC link BUS2 Load3 BUS4 Load4 Danish Power system Hybrid Dual-infeed HVDC system model Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 31

32 D1(A) Res(A) D2(A) IMF5(A) D3(A) IMF4(A) D4(A) IMF3(A) D5(A) IMF2(A) A5(A) IMF1(A) Incipient Stator Insulation Fault Detection of Permanent Magnet Synchronous Wind Generators Fault Analysis and Simulation Wind Turbine Condition Monitoring Fault Detection Fault Diagnosis/ Prognosis Generator Maintenance Scheduling Health Status Prediction Reliability Evaluation Design Improvement Based on Hilbert-Huang Transformation (HHT) Time(s) (a) Time(s) (b) The comparison of Discrete wavelet transform and Hilbert-Huang Transformation on inter-turn fault detection of PMSG The capability to detect the inter-turn short circuit fault at the minimum severity degree of.1488% is much better than the best record (2.78%) in the literature Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 32

33 33 Wind Turbine Power Quality Flicker Mitigation with reactive power control Wind Gearbox DFIG Transformer 2.5MVA 2 1 Z Zth Eth=11kV G Capacitor 3-blade turbine PCC Normal operation PWM converter PWM converter Wind turbine reactive power control by STATCOM In.1, SCR 2, v m/ s, SCR 2, v m/ s, In.1, k 9 k 9 k

34 34 Wind Power Integration Into Weak Power Systems POC voltage behavior in response to SCR and X/R ratio variations POC voltage response against in-feed wind power and grid parameters 1 SCR 4 and X/R 2

35 Magnitude (db) Phase (deg) 35 Coordinative Control of Active Power and DClink Voltage for Cascaded Converter Dc active distribution network Interface converter Grid V * DC link + * P - VDC link PI controller * P DAB Power Control Loop VDC link I DC * link P Inverter Power Control Loop V ref Phase Shift Generator PWM Generator DAB Inverter DAB converter Inverter Vabc Iabc Bode Diagram -5 C 1 S 1 S 2 S 5 S 6 C dc-link S 9 S 1 S 11 Inductor filter Proposed control Feed forward control Conventional control S 3 S 4 S 7 S 8 S 12 S 13 S Proposed control Feed forward control Conventional control DAB converter Inverter Frequency (rad/s) Vdc-link (5V/div) Vdc-link (5V/div) Conventional Control Proposed Control Feed forward Control Proposed Control PINV (8W/div) PINV (8W/div) PDAB (8W/div) PDAB (8W/div)

36 V1(V) V2(V) V1(V) V2(V) Harmonic Stability Analysis of Inverter-Fed Power Systems x 14 Kpc= time(s) Bus1 phase-to-phase voltage time(s) Bus2 phase-to-phase voltage Experimental results in unstable case (K pv =.53, K pc =8) Experimental Setup time(s) DG1 Voltage time(s) DG2 Voltage Experimental results in stable case (K pv =.4, K pc =8)

37 Wind Power in Electricity Market Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 37

38 Oscillation Performance and Wide-area Coordination Control of Power System with Large-scale Wind Farms Study the influence of wind farm integration on power system oscillation Design a wide-area damping control strategy, coordinating PSS, FACTS damping controller and wind farm damping controller Area 2 Gen 1 Bus 3 Bus 2 Bus 1 Gen 1 Bus 39 Line 9 Load 39 Line Gen 8 Load 26 Line 27 Load 29 Line 25 Line 26 Bus 37 Bus 26 Bus 28 Bus 29 Bus 25 Load 28 Line 24 Bus 27 Bus 38 Load 25 Gen 9 Bus 18 Line 2 Load 27 Bus 24 Bus 17 Gen 6 Load 24 Load 18 Bus 16 Bus 35 Bus 3 Load 3 Bus 15 Load 16 Line 31 Bus 21 Bus 22 Load 4 Load 15 Line 15 Load 21 Bus 8 Bus 5 Line 21 Line 2 Line 1 Line 1 Line 7 Line 6 Line 5 Line 4 Line 8 Line 3 Line 19 Bus 4 Bus 6 Bus 7 Load 7 Bus 31 Line 11 Load 31 Gen 2 Load 8 Bus 11 Bus 14 Load 12 Line 12 Bus 1 Bus 9 Bus 32 Bus 12 Bus 13 Area 1 Gen 5 Area 3 Gen 3 Line 22 Line 23 Line 16 Line 17 Line 18 Line 14 Line 13 Line 28 Line 3 Line 29 Load 23 Bus 19 Bus 23 Bus 36 Load 19 Bus 33 Gen 4 Gen 7 Bus 2 Bus 34 Line 32 Line 33 Contact: Professor Z Chen, Department of Energy Technology, Aalborg University, zch@et.aau.dk 38

39 Summary and outlook NORCOWE cooperation has produced some good results on Grid Integration of Offshore Wind Farms via VSC-HVDC Offshore Wind Farm Optimization ET-AAU has also been working on some technical solutions More challenges to be addressed, for example High voltage and high capacity cables, cable joint technologies for deep sea High power VSC HVDC links and multiterminal solutions Fault handing of DC electrical grids System reasonance and stability of power electronic integrated systems 39

40 4 ET-AAU welcome to develop national and internation collaboration with industry and research institutions. Thank You!