Coordinated Frequency Control Scheme of Offshore Wind Farm Connected to VSC-HVDC

Abstract

This article presents a coordinated control scheme enabling the voltage source converter-based high-voltage direct current (VSC-HVDC) transmission system connected offshore wind farm to provide frequency response. Once the onshore system frequency deviates, the proposed control strategy will be activated so that both the wind farm and the VSC-HVDC can work together to provide frequency support. In this approach, each wind turbine should operate in de-loading mode to acquire reserve under normal condition. On detecting the frequency event, not only the reserve and kinetic energy of each wind turbine can be utilized for frequency regulation by adjusting rotor speed, but the DC capacitor installed in the VSC-HVDC is arranged to participate in frequency control by slightly changing the DC-link voltage as well. The superior performance of the proposed control method has been verified by simulation.

Keywords:

• variable speed wind turbine
• offshore wind farm
• high-voltage direct current
• primary frequency control
• emulated inertia control

Additional information

Notes on contributors

Xiaoge Liu

Xiaoge Liu received his B.Eng degree in electrical engineering from Huazhong University of Science and Technology (HUST), China, in 2012. He has been awarded the degree of PhD by The Hong Kong Polytechnic University, Hung Hom, Hong Kong, in 2019. His research interests include wind turbine control and integration of renewable energy.

Zhao Xu

Zhao Xu is a Professor with The Hong Kong Polytechnic University, where he is currently Leader of Smart Grid research. He was previously with the Centre for Electric Power and Energy, Technical University of Denmark. He is currently an Editor for IEEE POWER ENGINEERING LETTERS, and Electric Power Components and Systems journal. He is serving as Deputy Chairman of IEEE PES joint Chapter, Hong Kong. His research interests include grid integration of renewable energies and EVs, electricity market planning and management, and big data and AI applications in power engineering.