Low-Order Frequency Response Modeling for Offshore Wind Farm-MTDC Systems

The increasing penetration of Renewable Energy Sources (RES) and (Multi-Terminal) High Voltage Direct Current (HVDC) is challenging the system frequency stability. The RES such as Wind Turbine Generators (WTGs) are being required to automatically provide frequency regulation support for the main grid. A Low-Order Frequency Response Model (LOFRM) is proposed for the complete Wind Farm (WF)-MTDC system in this paper. First, a high-order model that can be regarded as the virtual governor turbine is developed for the WF-MTDC system whose structure is similar to that of conventional generators. An LOFRM is then proposed to surrogate approximately the high-order model, whose parameters are determined by using a regression-based numerical method. The results show that the proposed LOFRM can properly approximate the complicated high-order model, and be acceptable if used for stability analysis and even maybe optimization problems.