Transient Overvoltage Security Region and Overvoltage Comprehensive Suppression Method for the Entire Fault Process in Renewable Energy Collection System Under Asymmetric Fault

During the asymmetric short-circuit period and the fault recovery stage of the renewable energy collection system, the non-fault phase and the PCC point show transient overvoltage characteristics, respectively, which threaten the safe and stable operation of the system. Aiming at the transient overvoltage problem during the asymmetric fault of the renewable energy collection system, this paper first establishes the sequence component equivalent circuit of the renewable energy collection system, deduces the expression of non-fault phase overvoltage at the fault point considering asymmetric fault ride-through control of renewable energy, and reveals the influence of negative-sequence reactive current of renewable energy on non-fault phase overvoltage. Secondly, combined with the system equation and the constraints of overcurrent and overvoltage, the safety region of the renewable energy current reference value under asymmetric fault is established. On this basis, the transient overvoltage comprehensive suppression strategy based on the optimization of the current reference value during fault and the rapid identification of fault clearing time is proposed, which realizes the overvoltage suppression in the full process of asymmetric fault. Finally, the renewable energy collection system is built in the Matlab/Simulink R2023b simulation platform, and the correctness and effectiveness of the transient overvoltage analysis and suppression strategy proposed in this paper are verified.