Novel Self-adjusted Full-line Current Protection Strategy for Small Resistance Grounding Distribution Network

The existing current break protection cannot achieve full-line current protection and may lose its protection capability. Therefore, a self-adjusted full-line current protection strategy based on a double-layer criterion is proposed. The first layer of the criterion adopts the adaptive adjustment threshold as the setting value to realize full-line fault monitoring, which is not affected by the system operation mode and fault type. The second layer is used to locate the fault section of the line and improve the selectivity of the protection strategy. Considering the difficulty in accurately identifying high-resistance ground faults using current protection, an identification method based on compound power is proposed by analyzing the zero-sequence network of the system. Simulation results show that the proposed protection strategy can realize full-length line protection and the effective identification of high-resistance ground faults and is not affected by the system load variation and fault type.