Analysis and suppression of offshore wind power broadband oscillation based on HVDC transmission technology

Abstract

This paper explores the dynamics of large-scale offshore wind farms comprised of full-power variable frequency wind turbines, interconnected with VSC-HVDC (voltage source converter-based high-voltage direct current) converter stations. These systems are susceptible to broad frequency oscillations due to the rapid response characteristics of power electronic devices, potentially compromising their operational safety and stability under various conditions. To mitigate the impact of these oscillations on offshore wind turbines and the connected systems, the study first outlines the structure and operational mode of the offshore wind power electronic system with VSC-HVDC transmission. It then analyzes the mechanisms underlying these broad frequency oscillations. Subsequently, the paper presents a model construction and stability analysis for wind farms and transmission systems. It specifically focuses on offshore wind power systems based on symmetric monopolar topology, involving multiple branches and multiple wind farm access points. The research includes an in-depth oscillation analysis, supported by real-world case studies, demonstrating that strategically optimized control and protection strategies can effectively reduce the oscillation risks associated with wind farms connected through VSC-HVDC systems, thereby ensuring their safe and stable operation.