BEST PATHS Project: Real-Time Demonstrator for the Integration of Offshore Wind Farms using Multi- Terminal HVDC Grids

Transcription

1 BEST PATHS Project: Real-Time Demonstrator for the Integration of Wind Farms using Multi- Terminal HVDC Grids Carlos UGALDE (Cardiff University, Wales) Salvatore D ARCO (SINTEF, Norway); Daniel ADEUYI, Sheng WANG, Jun LIANG and Nick JENKINS (Cardiff University, Wales); Salvador CEBALLOS, Maider SANTOS and Íñigo VIDAURRAZAGA (Tecnalia, Spain); Gilbert BERGNA (SINTEF, Norway); Mireia BARENYS (GAMESA, Spain); Max PARKER and Stephen FINNEY (University of Strathclyde, Scotland); Antonio GATTI, Andrea PITTO, Marco RAPIZZA and Diego CIRIO (RSE SpA, Italy); Per LUND (Energinet.dk, Denmark); and Íñigo AZPIRI and Aida CASTRO (Iberdrola, Spain). 7 th June 2017, London, UK

2 Outline of the Presentation 1. Introduction 2. The BEST PATHS Project 3. BEST PATHS Demo 1: a) Network Topologies b) Key Performance Indicators c) The Open Access Toolbox 4. Real-Time Demonstrator 5. Simulation and Experimental Results 6. Conclusions and Next Steps 2

3 Introduction Wind energy will be the most widely adopted renewable energy source (RES) by 2050 to contribute towards the abatement of green house gas emissions. A Business as Usual approach to improve infrastructure will not be sufficient to meet policy objectives at reasonable cost. Operators and manufacturers are now considering HVDC solutions over HVAC for offshore power transmission systems: o A higher quality and more reliable wind resource with higher average wind speeds is farther away from shore, and thus, o Long distances to shore. 3

4 Introduction (2) Voltage source converter (VSC) based schemes are becoming the preferred option over line commutated converter (LCC) alternatives due to their decoupled power flow control, black-start capability and control flexibility. MTDC grids will facilitate a cross-border energy exchange between different countries and will enable reliable power transfer from offshore wind farms (OWFs). The interactions between wind turbine converters and different VSC converter types in a meshed topology need further investigation. 4

5 BEST PATHS Project BEyond State-of-the-art Technologies for re-powering Ac corridors & multi-terminal Hvdc Systems Key Figures Budget of 62.8M, 56% co-funded by the European Commission under the 7 th Framework Programme for Research, Technological Development and Demonstration (EU FP7 Energy). Duration: 01/10/ /10/2018 (4 years). Composition: 5 large-scale demonstrations, 2 replication projects, 1 dissemination project. Key Aims Through the contribution of 40 leading research institutions, industry, utilities, and transmission systems operators (8), the project aims to develop novel network technologies to increase the pan- European transmission network capacity and electricity system flexibility. 5

6 BEST PATHS Demo #1 Objectives: 1. To investigate the electrical interactions between the HVDC link converters and the wind turbine (WT) converters in OWFs. 2. To de-risk multivendor and multi-terminal HVDC (MTDC) schemes. 3. To demonstrate the results in a laboratory environment using scaled models. 4. To use the validated models to simulate a real grid with OWFs connected in HVDC. 6 6

7 BEST PATHS Demo #1 (2) HVDC equipment manufacturers provide black boxes? R&D Centres We intend to use open models TSOs Utilities & RES developers Detailed models Simulation & Validation Independent Manufacturers 7 7

8 Network Topologies System configurations have been implemented in Simulink A number of topologies has been modelled, simulated and analysed. The topologies considered constitute likely scenarios to be adopted for the transmission of offshore wind energy in future years. Full details available in Deliverable D3.1 of the BEST PATHS project. Point-to-Point HVDC Link (Topology A) Grid #1 V ac_w1 WFC Onshore GSC P g1,q g1 Onshore AC Grid #1 V dc_g1 P w1 DC CABLE V ac_w1 * AC Voltage Control f w1 * θ w1 * V dc_g1 * V dc and Q Controller Q g1 * 8

9 Network Topologies (2) Three-Terminal HVDC System Grid #1 V ac_w2 WFC #2 Onshore P w2 AC Voltage Control θ w2 * DC NETWORK V ac_w2 * f w12 * Grid #1 V ac_w1 WFC #1 GSC #1 P g1,q g1 Onshore AC Grid #1 V dc_g1 P w1 V ac_w1 * AC Voltage Control f w1 * θ w1 * (V dc vs. P) and Q Controller V dc_g1 * Q g1 * 9

10 Network Topologies (3) Six-Terminal HVDC System with AC Links (Topology B) Grid #3 V ac_w3 WFC #3 Onshore GSC #3 P g3,q g3 Onshore AC Grid #3 V dc_g3 P w3 AC interlink V ac_w3 * AC Voltage Control θ w3 * f w3 * V dc_g3 * (V dc vs. P) and Q Controller Q g3 * Grid #2 V ac_w2 WFC #2 DC NETWORK GSC #2 P g2,q g2 Onshore AC Grid #2 V dc_g2 P w2 V ac_w2 * AC Voltage Control θ w2 * f w2 * V dc_g2 * (V dc vs. P) and Q Controller Q g2 * Grid #1 V ac_w1 WFC #1 GSC #1 P g1,q g1 Onshore AC Grid #1 V dc_g1 P w1 V ac_w1 * AC Voltage Control θ w1 * f w1 * 10 V dc_g1 * (V dc vs. P) and Q Controller Q g1 *

11 Network Topologies (4) Six-Terminal HVDC System with DC Links (Topology C) Grid #3 V ac_w3 WFC #3 Onshore GSC #3 P g3,q g3 Onshore AC Grid #3 V dc_g3 P w3 V ac_w3 * AC Voltage Control θ w3 * f w3 * V dc_g3 * (V dc vs. P) and Q Controller Q g3 * Grid #2 V ac_w2 WFC #2 DC NETWORK GSC #2 P g2,q g2 Onshore AC Grid #2 V dc_g2 P w2 V ac_w2 * AC Voltage Control θ w2 * f w2 * DC interlink V dc_g2 * (V dc vs. P) and Q Controller Q g2 * Grid #1 V ac_w1 WFC #1 GSC #1 P g1,q g1 Onshore AC Grid #1 V dc_g1 P w1 V ac_w1 * AC Voltage Control θ w1 * f w1 * V dc_g1 * (V dc vs. P) and Q Controller Q g1 * 11

12 Network Topologies (5) Onshore GSC #6 Pg6,Qg6 Onshore AC Grid #B Twelve-Terminal HVDC System with DC Links (Topology D) Vdc_g6 Vdc_g6* (Vdc vs. P) and Q Controller Qg6* DC NETWORK GSC #5 Pg5,Qg5 Vdc_g5 (100 km) Grid #3 Vac_w3 WFC #3 (10 km) WFC #6 Vac_w6 Grid #6 (Vdc vs. P) and Q Controller Vdc_g5* Qg5* Pw3 Pw6 GSC #4 Pg4,Qg4 Vac_w3* AC Voltage Control θw3* fw3* (10 km) (5 km) AC Voltage Control fw6* θw6* Vac_w6* Vdc_g4 Grid #2 Vac_w2 WFC #2 (10 km) WFC #5 Vac_w5 Grid #5 Vdc_g4* (Vdc vs. P) and Q Controller Qg4* Pw2 Vac_w2* AC Voltage Control θw2* fw2* (10 km) AC Voltage Control fw5* θw5* Vac_w5* Pw5 Onshore Vdc_g3 GSC #3 Pg3,Qg3 Onshore AC Grid #A Grid #1 Vac_w1 WFC #1 WFC #4 Vac_w4 Grid #4 (Vdc vs. P) and Q Controller Vdc_g3* Qg3* Pw1 AC Voltage Control AC Voltage Control Pw4 DC NETWORK GSC #2 Pg2,Qg2 Vac_w1* θw1* fw1* fw4* θw4* Vac_w4* Vdc_g2 (100 km) (Vdc vs. P) and Q Controller Vdc_g2* Qg2* GSC #1 Pg1,Qg1 Vdc_g1 12 Vdc_g1* (Vdc vs. P) and Q Controller Qg1*

13 Key Performance Indicators To assess the suitability of the models and proposed HVDC network topologies, converter configurations and control algorithms, a set of KPIs have been defined. Full details available in Deliverable D2.1 of the BEST PATHS project. KPI.D1.1 AC/DC interactions: power and harmonics Steady state Power quality WT ramp rates KPI.D1.2 AC/DC Interactions Transients & Voltage Margins Normal operation Extreme operation KPI.D1.3 DC Protection Performance / Protection & Faults Protection selectivity Peak current and clearance time KPI.D1.4 DC Inter-array Design Inter-array topology Power unbalance KPI.D1.5 Resonances AC systems oscillation Fault tolerance Motorising capability Internal DC resonance KPI.D1.6 Grid Code Compliance Active and reactive power Fault ride-through 13

14 The Open Access Toolbox A set of models and control algorithms has been developed, simulated and assessed. Their portability as basic building blocks will enable researchers and designers to study and simulate any system configuration of choice. These have been published in the BEST PATHS website as a MATLAB Open Access Toolbox: 14

15 The Open Access Toolbox (2) A user manual is also provided, together with the published models and accompanying examples. Specific blocks in the toolbox include: o High level controllers: three modes of operation including ac voltage and frequency, DC voltage and reactive power, and active and reactive power regulation; o Converter stations: averaged and switched of modular multilevel converters (MMCs); o AC grid: adapted from the classical 9-bus system; o DC cables: frequency-dependent, travelling wave model based on the universal line model; o Wind farm: a wind turbine generator (WTG) is modelled in detail. The current injection of a WTG is scaled to complete the rated power of the OWF. Full details of the models available in Deliverable D3.1 of the BEST PATHS project. 15

16 The Open Access Toolbox (3) Toolbox and user manual uploaded on BEST PATHS website on 14 th February. Presentation at 13 th IET ACDC2017; advertisement via social media and on project website. 1,258 new users have been recorded on the website since the toolbox was uploaded. Purposes of use Testing Type of organisation The toolbox has been downloaded by 60 different users. Information Research Evaluation o Universities include the Aalborg University, KU Leuven, the Fukui University of Technology, the Imperial College of London, the Technical University of Denmark, the University College of Dublin, Ensam, the Technical University of Darmstadt, the Technical University of Eindhoven, the Pontifical Comillas University, Cardiff University, the University of Strathclyde, and the University College London, King Fahd University of Petroleum and Minerals, Shanghai Jiao Tong University, Huazhong university and TU Kaiserslautern. o Research centres include the KTH Royal Institute of Technology, the SuperGrid Institute, GridLab, IREC (Institut de Recerca en Energia de Catalunya) and L2EP (Laboratoire d Electrotechnique et Electronique de Puissance, Lille). o Companies include Siemens, Tractebel, Sarawak Energy, Energinet.dk, DNV GL, IBM Research, SP Energy Networks, TenneT, Nissin, Enstore and SCiBreak. University Research centre Company 16

17 Real-Time Demonstrator Built in the premises of SINTEF (Trondheim, Norway), it aims to: Provide experimental validation to the results obtained from simulations: o Establish a correspondence between simulation and experimental setup on single components and at system level; o Identify relevant scenarios to test in the laboratory; o Perform experiments. Reduce risks of HVDC link connecting OWFs. Validate meshed HVDC grids with different VSC technologies. Foster new suppliers and sub-suppliers of HVDC technology. Facilities include: a four-terminal 50 kw HVDC grid with 3 VSC-based MMCs and 1 two-level VSC; a 20 kw synchronous generator; DC circuit breakers; a wind emulator; a real-time simulator system and control unit (OPAL-RT). 17

18 Real-Time Demonstrator (2) Further detail on the demonstrator available in Deliverable D8.1 of the BEST PATHS project. 18

19 Real-Time Demonstrator (3) National SmartGrid Laboratory (SINTEF) 19

20 Real-Time Demonstrator (4) MMC Power Cells Boards 20

21 MMC Assembling Stages Real-Time Demonstrator (5) 21

22 MMC Assembling Stages (2) Real-Time Demonstrator (6) 42 modules 144 power cell boards 1764 capacitors 22

23 KPI Assessment Summary (Simulation Results) KPI Description Status 1.1 Steady State AC/DC Interactions Fully Met 1.2 Transient AC/DC Interactions o Partially met Due to converter overloading and DC overvoltage during extreme conditions (e.g. AC faults). Overloading sustained for a very short time <300ms and braking resistor prevents overvoltage. 1.3 Protection Performance Fully Met 1.4 DC Inter-array Design Fully Met 1.5 Resonances Fully Met 1.6 Grid Code Compliance o Partially met Due to steady-state error between actual and reference active power during frequency oscillations on the AC grid of Topology A & B. Full details of the models available in Deliverable D3.2 of the BEST PATHS project. 23

24 Test System Wind Energy 2017 Simulation and Experimental Results Modelled in Simulink using the Open Access Toolbox. 300V AC Source The Grid Emulator creates 380 V AC and 690 V DC voltages in Lab. A step change in current references i d and i q is applied. Grid Emulator 200 kva 690V DC Source MMC12 60 kva MMC18 60 kva MMC arm currents and arm voltages are compared. Real Time Simulator 24

25 Simulation and Experimental Results (2) 12 Level MMC Active current reversal from 30 A to -30 A at 1.5 s Simulation Experiment Arm Currents Arm Voltages 25

26 Simulation and Experimental Results (3) 12 Level MMC Step in reactive current from 0 A to 10 A at 2.5 s Simulation Experiment Arm Currents Arm Voltages 26

27 Simulation and Experimental Results (4) 18 Level MMC Active current reversal from -30 A to 30 A at 1.5 s Simulation Experiment Arm Currents Arm Voltages 27

28 Simulation and Experimental Results (5) 18 Level MMC Reactive current step from 0 A to -10 A at 2.5 s Simulation Experiment Arm Currents Arm Voltages 28

29 Conclusions and Next Steps Main Contributions of this Work A set of models and control algorithms has been developed, simulated and assessed. These have been published as an Open Access Toolbox. Network topologies constituting likely scenarios for the transmission of offshore wind energy have been proposed. To assess the suitability of the models, topologies and control algorithms, a set of KPIs have been defined. An experimental demonstrator for the integration of grid-connected OWFs using HVDC grids has been presented. Preliminary results demonstrating the capabilities of the demonstrator have been compared against simulation results. These show good agreement. 29

30 Conclusions and Next Steps (2) Main Contributions of this Work (continued) The main contribution of this work is the provision to TSOs, utilities, manufacturers and academic institutions with simulation and experimental tools to generate the necessary knowledge for the development, construction and connection of MTDC systems aiming to help de-risking the use of MTDC grids for the connection of OWFs. On-Going and Future Work Conclude commissioning of the demonstrator facilities. Using the real-time experimental demonstrator, conduct tests for different system topologies representing future scenarios to validate simulation results obtained using computational tools. Make the demonstrator available to interested parties for R&D activities. 30

31 Wind Energy 2017 Questions? Dr Carlos UGALDE Cardiff University, Wales, UK The authors gratefully acknowledge the financial support provided by the EU FP7 Programme through the project BEyond State of the art Technologies for re- Powering AC corridors & multi-terminal HVDC Systems (BEST PATHS), grant agreement number