Implementation method of selective low-voltage leakage protection based on additional direct current
WU Qian1,2,3, ZHOU Shaoliang1,2,3
1. State Grid Electric Power Research Institute, NARI Group Corporation, Nanjing 211006; 2. NARI Technology Co., Ltd, Nanjing 211006; 3. State Key Laboratory of Smart Grid Protection and Operation Control, Nanjing 211006
Abstract：Selectivity is one of the basic requirements of low-voltage leakage protection, and it is also one of the standards to measure whether low-voltage leakage protection is qualified. In this paper, the shortcomings of conventional low-voltage leakage protection with additional direct current (DC) components are discussed, and a new implementation method of selective protection based on additional DC is proposed. The alternating current (AC) and DC sampling components installed on the branch are used to collect and calculate the AC and DC current of each branch, and select the faulty branch through a specific algorithm according to the magnitude and direction of the AC and DC current. This discrimination method solves the problem of no selectivity of additional DC, which has the advantages of simple structure, small number of devices, strong applicability, easy expansion, and high reliability, and can meet the selective requirements of low-voltage leakage protection.
2022, Vol. 23 
