A review of inertia and frequency control technologies for variable speed wind turbines

With high penetration of wind energy into modern power systems, a gradual displacement of conventional thermal generator by wind farms and the fluctuating nature of wind speed will result in dynamic active power imbalance leading to corresponding frequency stability issues. Thus, this topic draws a growing attention from industry and academia all over the world devoted to the design, development and application of auxiliary frequency regulation function by variable speed wind turbine (VSWT) for the last couple of years. This paper mainly features a comprehensive overview on industry design and applications, ongoing research activities as well as various national technical requirements regarding the VSWT frequency regulation and spinning reserve. Further, the contribution of offshore HVDC wind farm to power system frequency regulation is discussed in depth.