基于模型识别的平行线路零序方向元件

分析指出,平行线路区内故障时的零序电源可等效为一个位于区内的电压源,零序电路符合电感模型,线路区外故障时的零序电源则可等效为一区内电压源和一区外电压源的叠加,零序电路不再满足电感模型.所以区内故障时,电感模型误差很小,区外故障时,电感模型误差很大.通过计算模型误差,结合传统的零序方向元件,提出了一种基于模型识别的平行线路零序方向元件的新原理,能够有效防止区外故障时的保护误动,当本线内部故障时,保护的灵敏度随动作时间自适应提高,可以快速动作切除故障.理论分析和EMTP仿真实验表明,新原理利用全部故障暂态信息,在时域中计算而无需滤波,区内故障时保护动作灵敏,区外故障时保护则快速闭锁,可靠性很高.

A New Type of Zero-Sequence Directional Relay Based on Model Recognition for Parallel Lines

The mal-operation of pilot zero-sequence direction protection working on parallel lines is usually caused by the zero-sequence mutual inductance. By analyzing zero-sequence network of parallel lines, an inductance circuit model is established for the internal fault, and a novel zero-sequence directional relay based on model recognition is proposed for parallel lines. When the in-ternal fault occurs, the model error is small and decreases quickly, and when the external fault occurs, the model error is large and oscillates. By computing the model error, the performance of the conventional zero-sequence directional relay is improved. The theoretic analysis demonstrates the validation of the new relay.