现代配电网继电保护技术及其发展

Modern distribution systems relay protection technology and its development

随着供电安全性与可靠性要求的提高以及分布式电源(distributed electric resource,DER)的大规模接入,配电网继电保护成为一个热门研究领域。综述了中压配电网保护的发展历程、技术现状与亟待解决的问题。针对相间短路保护优化提升的需求,介绍了兼顾动作快速性与选择性的电流保护方案;提出基于短路电流边界值评估DER对保护的影响,给出了DER高度渗透配电网电流保护拒动与误动问题的解决方案。分析了防止触电与电气火灾事故对接地故障保护提出的新要求,介绍了小电流接地故障暂态方向保护技术及其应用情况,提出了基于零序电流与故障相电压同步变化关系的小电阻接地系统高阻接地保护新方法。指出电压/频率原理防孤岛保护难以兼顾DER在配电网故障时快速解列与大电网扰动时穿越运行的要求,为此提出了故障量加速防孤岛保护方案;建议研发信号协同注入法等新型防孤岛保护技术,以彻底解决电压/频率保护存在动作死区以及在大电网扰动时误动的问题。

With the improvement of power supply safety and reliability requirements and the large-scale access of distributed electric resource(DER),the relay protection of distribution network has become a very active research field.The development process,technical status and problems to be solved of medium voltage distribution network protection are summarized.Aiming at the demand of optimization and improvement of phase-to-phase short-circuit protection,a current protection scheme considering both rapidity and selectivity is introduced.The influence of DER on protection is evaluated based on the boundary value of short-circuit current,and the solution to the problem of current protection rejection and misoperation of DER highly penetrating distribution network is given.The new requirements for grounding fault protection to prevent electric shock and electrical fire accidents are analyzed.The transient direction protection technology and its application of small current grounding fault are introduced.A new method of high resistance grounding protection for small resistance grounding system based on the synchronous change relationship between zero sequence current and fault phase voltage is proposed.It is pointed out that the anti-islanding protection based on voltage/frequency principle is difficult to take into account the requirements of fast splitting of DER in distribution network fault and crossing operation in large power grid disturbance.Therefore,a fault acceleration anti-islanding protection scheme is proposed.It is recommended to develop new anti-islanding protection technologies such as signal co-injection method to completely solve the voltage/frequency.