基于综合阻抗比较原理的广域继电保护算法

将两端输电系统的综合阻抗保护原理推广到三端或多端输电系统,提出一种新型广域继电保护算法。针对广域保护区域不同故障时综合阻抗的定义和计算分析,区外故障时,综合阻抗反映区域内线路等效容抗,其虚部大小为千欧级,阻抗角约为90°;区内故障时,综合阻抗反应系统阻抗,其虚部大小不大于600,阻抗角在～90°之间,二者有明显区别。同时,结合广域继电保护对引起差流启动时的不同情况分析,提出三步保护方案以实现输电系统故障判断,正常运行时测量信息错误或变电站直流消失等运行工况的可靠保护。IEEE 10机39节点系统仿真结果表明:该算法容易整定,具有选相能力,且不受分布电容电流和过渡电阻影响,与广域差动保护相比具有较高的灵敏度。

A Study of Wide-Area Protection Algorithm Based on Integrated Impedance Comparison

This paper extends integrated impedance protection to multiple terminal transmission system in order to realize wide area protection,and discusses integrated impedance definitions and calculation analysis.The integrated impedance reflects line capacitive reactance when external fault occurs,and its magnitude reaches several kilo-ohms and its impedance angle is in-90°or so.In contrast,the amplitude of integrated impedance is no more than 600? and impedance angle is about ?? ～90° when internal fault occurs.Then,the three-step protection scheme is also presented based on the different situation analyses caused by wide-area protection differential current activated,which always realizes transmission system reliable protection when internal fault,measurement errors or substation DC disappear occur.Simulation tests based on IEEE 10-machine and 39-bus system illustrate that this algorithm could be set conveniently and could select phase naturally,the fault estimation results are immune to distributed capacitive current and grounding resistance,which has helpful applied prospect in wide area protection domain.