Transient Frequency Stability Emergency Control for the Power System Interconnected with Offshore Wind Power through VSC-HVDC

For the power system interconnected with the large-scale offshore wind power through VSC-HVDC, such as SZ power grid, it may be engaged with transient frequency stability and lack of related control due to the randomness, fluctuation and intermittence of the wind. This paper proposes a transient frequency control strategy for the power system interconnected with offshore wind power through VSC-HVDC based on sensitivity. Firstly, the structure of SZ power grid and the calculation method of transient frequency stability index are introduced, and the transient frequency problems existing in SZ power grid are explored. Secondly, the mathematical formulation for the transient frequency control is described, including the objective function and the constraints. Furthermore, a transient frequency emergency control strategy based on special sequence and the sensitivities is proposed, which includes thermal units regulation, wind power regulation, DC modulation and load shedding. Finally, the effectiveness of the proposed control strategy is verified by simulation in SZ power grid.