Fault Protection of Small Resistance Grounding System Based on Zero Sequence Voltage-Current Waveform Comparison Coefficient

Zero sequence overcurrent protection is mainly applicable to distribution networks. However, due to the complex environment of distribution network feeders, the existing zero sequence overcurrent protection schemes cannot meet the requirements of rapid and sensitive detection of single-phase high-resistance ground faults. To solve this problem, this paper analyzes the relationship between zero sequence current and zero sequence voltage of single-phase fault line and non-fault line in a small resistance grounding system and proposes a protection algorithm based on the comparison coefficient between zero sequence current and zero sequence voltage waveform after a quarter period shift to the left. First, the zero-sequence current and zero-sequence voltage of the line are sampled, and the zero-sequence voltage waveform is shifted to the left by a quarter period. Then, the zero sequence current and zero sequence voltage are standardized by the z-score method, and the waveform comparison coefficient K is calculated. Finally, according to the line waveform comparison coefficient K, the single-phase ground fault of the line is detected. This method improves the sensitivity of single-phase high-resistance grounding fault protection. Simulation tests based on the MATLAB/SIMULINK platform verify the effectiveness of the proposed algorithm.