Cooperative frequency control optimization strategy for photovoltaic-energy storage system

The frequency control strategies such as droop control and virtual inertia control are generally used to maintain frequency stability in the renewable energy system dominated power system. Previous studies mainly considered the frequency stability of power system and less concerned about the frequency regulation capability. In this paper, a cooperative optimization strategy for frequency control is proposed to adjust the frequency control parameters when disturbances occur and obtain the optimal frequency regulation capability. In the proposed strategy, the frequency nadir deviation constraint is used to describe the regulation capability and is represented by a fitting binary polynomial according to the low-order frequency response model. The disturbance load is estimated by the initial frequency drop sequence. The optimization model is computed as a linear constrained nonlinear multivariable function problem and can be solved efficiently. Case studies in a four-machine two-area test system verify the effectiveness of the strategy.