电气主设备纵差保护的进展

根据比率制动式纵差保护在运行中提出的问题 ,主要是电流互感器在外部短路暂态过程中造成的纵差保护不平衡电流增大和饱和效应使制动电流减少 ,可能产生误动作 ,发电机或变压器绕组短路时一侧可能存在不大的流出电流会影响保护动作的灵敏性 ,甚或造成保护拒动 ,这种流出电流可能是负荷电流 ,也可能是由短路安匝对健全绕组的互感所引起的感应电流。作者吸取国内外先进经验 ,结合主设备内部故障的分析建议推广标积制动原理的比率制动或纵差保护新方案

Progress of longitudinal differential protection for electrical main equipment

In terms of the problems occured during the ratio restraint longitudinal differential protection operating especially the restraint current is decreased owing to the increment of unbalanced current and saturation of the longitudinal differential protection caused by CT in external short circuit transient fault. Therefore maloperation will be resulted in. Moreover, a certain amount of out_flow current maybe exist on the primary side of generator or transformer at short circuit fault on windings. It will decrease the sensitivity of the protection or bring the protection in non_operation. The outflow current maybe load current, or maybe inductive current caused by transforming of short circuit fault to health windings. Advanced experiences at home and abroad are absorbed in this paper, together with analysis on internal fault at the main equipment, a new scheme for ratio restraint or longitudinal differential protection in scalar product restraint principle is proposed.