特高压交流输电线路接地阻抗继电器动作特性分析

针对特高压交流输电线路分布电容大、故障后渡过程明显的特点,从分布参数线路模型入手,分析了正常运行和接地故障状态下,接地阻抗继电器测量阻抗的变化规律,证实了故障情况下测量阻抗与故障距离呈双曲函数关系,提出了一种新型接地阻抗继电器电流接线方式,并探讨了P值常数化、线性化的相关问题.理论分析和测试结果表明:对于400 km以下的特高压交流输电短线路,接地阻抗继电器可以基于集中参数模型整定;但是对于400 km以上的长线路,在基于分布参数模型整定阻抗继电器和采用新型电流接线方式的基础上,方向性接地阻抗继电器能够正确判别故障发生、检测故障位置.

Analysis of Ground Impedance Relay Operation Characteristics for UHV AC Transmission Lines

In this paper, the characteristics of the measuring impedance are discussed under load operation and ground fault conditions based on the distributed parameter line model due to the large shunt capacitance, the high voltage level and the long transmission radius for UHV AC transmission lines. The hyperbola function relationship between the measuring impedance and the fault distance has been established. A novel residual compensation mode for ground impedance relays is proposed and correlative issues, such as normalization and linearization of factor P, are also discussed. Theoretical analysis and case test results show that the ground impedance relay can be set based on the lumped parameter line model if the length of a UHV AC transmission line is less than 400 km. Otherwise, the directional ground impedance relay must be set based on the distributed parameter model and the residual compensation mode should be used.