Existing current break protection cannot protect the full length of the line and may lose the protection range. Thus an adaptive full-line current protection method with double-layer criterion is proposed. The protection method first realizes the full-line fault monitoring that is not affected by the system operation mode and fault type through the low adaptive adjustment value in the first layer of the criterion. Then it uses the second layer of the criterion to locate the line fault section to ensure the correct protection action. Considering that it is difficult to accurately identify high-impedance ground faults for current protection, a method based on composite power is proposed by analyzing the zero-sequence network of the system. Simulation results show that the proposed protection method is not affected by system load changes and fault types. This can effectively improve the protection range of distribution network lines and the identification ability of high-impedance ground faults, and ensure the reliability and sensitivity of protection actions.

This work is supported by the Intergovernmental International Science and Technology Innovation Cooperation Key Project of National Key Research and Development Program of China (No. 2022YFE010124).