适应多点接地故障的小电阻接地系统集中式保护

Centralized Protection for Low-resistance Grounding System Under Multi-point Grounding Fault

小电阻接地系统中多点(含多条出线)同时接地时,各条故障出线零序电流将明显减小,传统零序过电流保护的灵敏度会降低。本文提出一种基于各出线零序电流幅值与相位比较、适应多点接地故障的保护方法,利用集中式保护装置收集各出线零序电流信息,利用出线或中性点零序电流幅值启动保护,选择零序电流幅值大于其他任意一条出线确定倍数且相位超前其一定角度的出线为故障出线。该方法从原理上对传统零序过电流保护方法作出改进,对单点接地故障以及多点接地故障实现保护,有效提高了小电阻接地系统接地故障保护的可靠性及灵敏性,仿真验证了算法的可行性。

When a low-resistance grounding system is under multi-point(including multi-outlet)in-phase grounding fault,the zero-sequence current on faulty outlets will decrease obviously,and the sensitivity of the traditional zero-se. quence over-current protection will be reduced accordingly. Based on the comparison of amplitude and phase of zero-se. quence current between different outlets,a protection method suitable for multi-point grounding fault is proposed in this paper,in which a centralized protection device is used to collect the zero-sequence current information about each out. let;the protection is started by means of the zero-sequence current amplitude of the outlet or neutral point,and the line whose zero-sequence current amplitude is larger than that of any other one by a factor of a fixed number and whose phase leads by a certain angle is selected as the faulty outlet. The proposed method improves the traditional zero-se. quence over-current protection method in principle and realizes the protection under single- and multi-point grounding fault,which can effectively improve the reliability and sensitivity of grounding fault protection for the low-resistance grounding system. Finally,simulation results verify the feasibility of the proposed algorithm.