防止过负荷时相间距离Ⅲ段保护误动的新方法

摘要

For two large electric power grids that are interconnected via multiple AC lines, when one or several lines are tripped after fault, the load of tripped lines will transfer to the remain running lines, and thus so-called “emergency overload” occurs. The zone Ⅲ relay may disconnect the overloaded lines and cause large area blackout. A new method is proposed to prevent such kind of maloperation by adding a control element to zone Ⅲ component. Based on RTDS, a simulation model is set up and proves that the new method can prevent maloperation of distance protection caused by emergency overload effectively and unblock zone Ⅲ distance protection when fault does happen.%两个大电网通过多回交流线路互联,在系统发生故障切除一回线或多回线情况下,被切除线路的负荷转移到剩余的运行联络线上,形成事故过负荷,此时运行线路中的距离Ⅲ段元件可能动作切除过负荷线路,引发大范围的停电事故.提出了一种新的方法,为相间距离保护Ⅲ段元件增加了限制条件,可以有效防止相间距离保护Ⅲ段元件在事故过负荷时误动.通过RTDS搭建了系统模型,验证了该方法既可有效防止过负荷时距离保护Ⅲ段保护误动,又能够保证在故障时可靠开放距离保护Ⅲ段保护.