In current photovoltaic transmission systems, low voltage ride-though is a main challenge that restricts the development of photovoltaic power generation. In this study, a power system with large photovoltaic (PV) power penetration is considered, and nonlinear control strategies for PV power stations are designed to guarantee the operation of PV power system and provide enough reactive power for the grid. First, the dynamic model of PV stations is constructed, and the control objective is to enhance the robustness of the system against grid faults. Second, the state-dependent Riccati equation (SDRE) technique is used to solve the robust control problem. The SDRE technique reconstructs a nonlinear system to a linear-like structure, and controls the system through solving an algebraic Riccati equation (ARE)-like approach with state-dependent coefficient (SDC) matrices. Comparisons with conventional PI controllers are performed, and better control performance is achieved through the proposed strategy.

Low voltage ride-though; Photovoltaic power station; Reactive power support; State-Dependent Riccati equation;