A Collaborative Optimization Method of Dual Criteria Based on Dynamic Correction of Positive Sequence Phase Difference and Adaptive Setting of Negative Sequence Amplitude Ratio Threshold

Aiming at the problem that the high proportion of distributed photovoltaic (PV) access leads to the increase of the misoperation rate of traditional directional protection, this paper proposes a dual-criterion collaborative optimization method based on the dynamic correction of the positive sequence phase difference and the adaptive setting of the negative sequence amplitude ratio threshold. First, the characteristics of the positive sequence current phase shift during faults are analyzed, and an adaptive criterion correction algorithm considering the influence of PV access is proposed to solve the problem that the traditional fixed criterion cannot be applied to the access of distributed PV. Second, a correlation function among the negative sequence current amplitude ratio, PV penetration rate, and transition resistance is constructed, and a dynamic threshold setting model is proposed to solve the problem of the failure of the amplitude ratio criterion in high-resistance fault scenarios. Simulation verification shows that when the PV penetration rate is 40% and the transition resistance is 50 [Formula: see text], the accuracy of the proposed criterion for direction discrimination reaches 97.5%, which is 21.3% higher than that of the traditional positive sequence phase difference criterion and 18.6% higher than that of the negative sequence amplitude ratio criterion with a fixed threshold. The research results provide a highly reliable solution for the protection of PV distribution networks in high-resistance fault scenarios.