平行线弱电强磁模型下零序方向元件改进

Improvement of Zero-sequence Directional Relay for the Parallel Line with Magnetically Strong and Electrically Weak Connection

针对近来几起高压电网中由于线路零序互感影响而导致的纵联零序保护误动事件,分析了出现这种问题的弱电强磁联系的典型电网结构形式,研究了相邻线互感对纵联零序方向元件的影响,并分析了几种解决方法,提出采用一种新型的基于故障类型的零序方向元件,分析了该元件的可行性和具体方案流程,结合2次现场事例的数据分析验证了该方法的正确性。

According to the several real-operation accidents of zero-sequence pilot protection happened recently in the high- voltage power network due to the influence of zero-sequence mutual inductance between power lines, this paper analyzes the typical power network topologies with magnetically strong and electrically weak connection that caused the mal-operation. The influence of zero-sequence mutual inductance on the behaviors of zero-sequence pilot protection is studied in detail and several countermeasures are analyzed. A new type of zero-sequence directional relay based on fault type is proposed and the feasibility and detail scheme flow are described. The scheme is validated to be correct by the data analysis of two local examples.