An HVDC transmission system is prone to generate overvoltage at the sending end after the DC block fault, which will present a challenge of high voltage ride-through(HVRT) for generators at the sending end. To ensure safe operation of the hybrid power system with large-scale photovoltaic power stations, a nonlinear HVRT control strategy based on state-dependent Riccati equation (SDRE) technique is proposed. The optimal control law is obtained by solving an algebraic Riccati equation (ARE)-like problem. Through the selection of the weight matrix and optimization calculation of state dependent coefficient (SDC) matrices, the control objective to maintain terminal voltage is achieved during the transient period. Compared with PI control strategy, the proposed method can make full use of converter control ability to suppress overvoltage at sending end, and have better transient control performance during fault period.

HVDC transmission system; PV power control; Sending end overvoltage suppression; State-Dependent Riccati equation