Delft University of Technology Offshore VSC-HVDC Networks Impact on Transient Stability of AC Transmission Systems van der Meer, Arjen DOI 10.4233/uuid:ea19a35c-96e3-4734-82bb-f378d262cbc0 Publication date 2017 Document Version Final published version Citation (APA) van der Meer, A. (2017). Offshore VSC-HVDC Networks: Impact on Transient Stability of AC Transmission Systems. https://doi.org/10.4233/uuid:ea19a35c-96e3-4734-82bb-f378d262cbc0 Important note To cite this publication, please use the final published version (if applicable). Please check the document version above. Copyright Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policy Please contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. This work is downloaded from Delft University of Technology. For technical reasons the number of authors shown on this cover page is limited to a maximum of 10. Offshore VSC-HVDC Networks Impact on Transient StabilityStability ofof AC TransmTransmissionission SystemsSystems ArjenArjen A. van der MeeMeerr . Offshore VSC-HVDC Networks Impact on Transient Stability of AC Transmission Systems Proefschrift ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus prof.ir. K. C. A. M. Luyben, voorzitter van het College voor Promoties, in het openbaar te verdedigen op dinsdag 12 september 2017 om 10:00 uur door Arjen Anne VAN DER MEER, Elektrotechnisch ingenieur, geboren te Dokkum, Nederland. Dit proefschrift is goedgekeurd door promotoren: Prof.ir. M. A. M. M. van der Meijden en Prof.dr.eng. J. A. Ferreira en co-promotor: dr.ir. M. Gibescu Samenstelling promotiecommissie: Rector Magnificus voorzitter Prof.ir. M. A. M. M. van der Meijden Technische Universiteit Delft, promotor Prof.dr.eng. J. A. Ferreira Technische Universiteit Delft, promotor dr.ir. M. Gibescu Technische Universiteit Eindhoven, co-promotor Onafhankelijke leden: Prof.dr. P. Palensky Technische Universiteit Delft Prof.dr. S. J. Watson Technische Universiteit Delft Prof.dr. K. Uhlen Norwegian University of Science and Technology Prof.dr. R. Iravani University of Toronto This research described in this thesis was financially supported byAgentschap NL, an agency of the Dutch Ministry of Economic Affairs, under the project North Sea Transnational Grid (NSTG). NSTG was a joint project of Delft University of Technology and the Energy Re- search Centre of the Netherlands (http://www.nstg-project.nl/). Cover design by Ellen-Claire Boomsma-Hulsegge Published and distributed by: Arjen Anne VAN DER MEER E-mail: [email protected] WWW: https://vdrmeer.org/ ISBN 978-94-6299-652-6 Keywords: Transient Stability, VSC-HVDC, co-simulation, offshore wind Copyright © 2017 by Arjen Anne VAN DER MEER All rights reserved. No part of the material protected by this copyright notice may be re- produced or utilised in any form or by any means, electronic or mechanical, including pho- tocopying, recording or by any information storage and retrieval system, without written permission of the author. Printed in The Netherlands by Ridderprint B.V. (https://www.ridderprint.nl) to my beloved colleague Nakisa Farrokhseresht Contents Summary 1 Samenvatting 5 1 Introduction 9 1.1 Context . 9 1.1.1 Gradually Increasing RES Penetration . 9 1.1.2 High-Voltage Direct Current Transmission . 11 1.1.3 Grid Integration of Offshore Wind Power and VSC-HVDC . 12 1.1.4 Simulation Aspects of VSC-HVDC and offshore WPPs . 13 1.2 Research Challenges and Problem Definition . 14 1.3 Research Objectives and Approach . 17 1.4 Scientific Contribution . 19 1.5 Research Framework . 20 1.6 Outline of the Thesis . 21 2 Operational Aspects and Modelling Requirements 23 2.1 Operation of VSC-HVDC Transmission . 23 2.1.1 Historical notes on HVDC Transmission . 23 2.1.2 VSC-HVDC Components and Terminal Layout . 25 2.1.3 VSC operation and control principles . 28 2.2 Deployment and Operating Characteristics of Offshore Wind Power . 31 2.2.1 Operation of Wind Turbines . 31 2.2.2 Wind Power Plants . 37 2.2.3 Wind power as a primary source . 39 2.3 Transnational Offshore Networks by VSC-MTDC . 41 2.3.1 HVDC-side operation and control . 41 2.3.2 Offshore Network Topology Options . 43 2.4 Potential impacts of VSC-HVDC and Modelling Requirements . 44 2.4.1 Fault Response of VSC-HVDC and WTGs . 45 2.4.2 Dynamic Behaviour of VSC-HVDC and Grid Code Require- ments . 46 2.4.3 Modelling and Simulation Needs . 49 vii viii CONTENTS 3 Modelling of VSC-HVDC and Wind Power Plants 53 3.1 VSC-HVDC representation and control . 53 3.1.1 Model Assumptions and Grid Interface . 53 3.1.2 Vector Control . 55 3.1.3 Per Unit System . 55 3.1.4 Phase-Locked Loop Model . 57 3.1.5 Inner Current Controller . 60 3.1.6 Current Limiter and Rate Limiter . 62 3.1.7 Outer Controllers . 64 3.1.8 Direct Control . 66 3.1.9 Power balance model . 67 3.2 Wind Turbine Generator Model . 67 3.2.1 Input-Output Representation . 68 3.2.2 WTG Network Interface . 68 3.2.3 Aerodynamic Model . 69 3.2.4 Shaft Representation . 69 3.2.5 Pitch Controller . 70 3.2.6 Active-Power Controller (d-axis Controller) . 71 3.2.7 Voltage-Amplitude Controller (q-axis controller) . 72 3.3 Fault Ride-Through of VSC-HVDC Connected Offshore Wind Parks . 72 3.3.1 Power Reduction Methods . 73 3.3.2 Implementation into Onshore and Offshore VSC Control . 76 4 VSC-MTDC modelling for Transient Stability Simulation 79 4.1 Introduction . 79 4.2 Simulation Framework . 81 4.2.1 Stability-type simulation . 81 4.2.2 EMT-type simulation . 85 4.3 Quasi-stationary VSC-MTDC model . 88 4.3.1 AC-side Grid Interface and Controls . 88 4.3.2 DC grid interface and Power Balance Model . 90 4.3.3 State-Space Model of VSC-MTDC for Stability Studies . 91 4.3.4 Inclusion of VSC-HVDC into Power Flow Analysis . 93 4.4 Improved State-Space Modelling by Multi-Rate Techniques . 94 4.5 Reduced-order State-Space MTDC Model . 95 4.6 Simulation Studies . 96 4.6.1 Simulator Validation Against PSS®E and PSS®NETOMAC . 96 4.6.2 Validity of the Quasi-Stationary Model . 99 4.6.3 Comparison between Transient Stability Models . 100 4.7 Summary and Conclusions . 103 5 Simulation of VSC-MTDC by Hybrid Methods 107 5.1 Introduction . 107 5.2 Literature Overview and Contribution of this Chapter . 108 5.2.1 Literature Overview on Co-Simulations . 108 CONTENTS ix 5.2.2 Literature Overview of Hybrid Stability and EMT simulations 111 5.2.3 Contribution of this Chapter . 113 5.3 Hybrid EMT-type and Stability-type Simulation . 114 5.3.1 Overview of Interfacing Techniques . 114 5.3.2 Implementation of Existing Interfacing Techniques in this Thesis115 5.4 Interface Technique Improvements in this Thesis . 125 5.4.1 Thévenin Impedance recalculation during faults . 125 5.4.2 The External System Priority Interaction Protocol . 126 5.4.3 Improved Angular Magnitude filtering . 127 5.4.4 Improved External System Priority IP during ac-side events . 127 5.4.5 Interaction Protocol Improvements Under Small Time Step- Size Conditions . 128 5.5 Simulation Studies . 129 5.5.1 Simulation Setup . 129 5.5.2 Application of existing interfacing techniques . 134 5.5.3 Interface Technique Improvements for VSC-HVDC . 138 5.5.4 Application of the Advanced Interfacing Techniques to VSC- MTDC . 143 5.6 Summary and Conclusions . 145 6 Stability Assessment of Hybrid AC/VSC-HVDC Networks 149 6.1 Introduction . 149 6.2 Study Approach and Simulation Setup . 150 6.2.1 Approach . 150 6.2.2 Scenario Selection . 154 6.2.3 System Description . 156 6.2.4 Parameter Selection and Case Study Setup . 162 6.2.5 Response Variable Treatment . 165 6.3 Case Study 1: Stability Impacts of FRT and Post-FRT of VSC-HVDC links . 166 6.3.1 Stability impacts of VSC-HVDC FRT . 166 6.3.2 Stability impacts of active power recovery . 168 6.3.3 Effect of VSC-HVDC connected offshore wind power penet- ration . 168 6.3.4 Influence of Converter-Interfaced Onshore Generation . .170 6.4 Case Study 2: Stability Impacts of a Future Offshore VSC-HVDC Grid 171 6.4.1 Effect of post-fault active power recovery on onshore dynamics 171 6.4.2 Radial versus meshed HVDC topology . 171 6.5 Case Study 3: Stability Support by VSC-MTDC . 173 6.5.1 Robust direct voltage control of MTDC transmission . 173 6.5.2 Stability support assessment . 174 6.5.3 Computational considerations . 176 6.6 Summary . 177 7 Conclusions and Recommendations 179 x CONTENTS 7.1 Conclusions . 179 7.1.1 Development of VSC-HVDC models for FRT analysis . 179 7.1.2 Combined EMT and stability-type Simulation Framework . 180 7.1.3 Improved Monolithic Modelling and Simulation Techniques for Transient Stability Studies . 180 7.1.4 Advanced Hybrid EMT and Stability Simulation of VSC-HVDC181 7.1.5 Stability impacts of multi-terminal VSC-HVDC transmission . 182 7.2 Recommendations for Further Research . 182 7.2.1 Quasi-stationary Modelling of VSC-HVDC . 182 7.2.2 Hybrid Simulations . 183 7.2.3 Stability Support of VSC-HVDC . 183 A Iterative Procedure for Systems of Non-Linear Equations 185 A.1 Fixed-point iteration .