Overview of Coordinated Frequency Control Technologies for Wind Turbines, HVDC and Energy Storage Systems

Modern grids contain new components, such as renewable power resources, HVDC transmissions, energy storage systems and others. These new components will affect the frequency-response characteristics in power systems. That is, some power electronics-based elements with according control schemes will replace a part of traditional thermal or hydro generators with governor droop control. Thus, novel frequency control technologies for energy storages, HVDC or energy storage systems should be studied. This paper summarized frequency control technologies for the abovementioned components, and discussed about the hybrid energy systems with control schemes. Additionally, some significant trends, including the optimal design of capacity size, adaptive droop or inertia gains of controllers, detailed models for small-signal analyses or grid forming controls, and simplified frequency-response models, were also investigated in this paper.