一种改进的纵联零序方向保护方案

相较于单回线,同塔双回和多回输电线路发生故障时零序特征更为复杂多变,导致传统的纵联零序方向保护误动或拒动频发。首先从灵敏度、弱电强磁和跨线故障三个方面分析了传统纵联零序方向保护的性能,指出其中存在的问题。然后,提出了一套新型的纵联零序方向保护方案:通过零序方向电压补偿算法提升零序方向元件在高阻故障下的灵敏度,通过零序综合方向元件消除零序互感的影响,构造了跨线故障识别逻辑。最后,通过三个现场实例分析,验证了该算法的有效性。

An improved pilot zero-sequence power directional relay scheme

Compared with single-circuit transmission lines, the zero-sequence characteristics of double-circuit and multi-circuit transmission lines on the same tower are more complex and changeable, resulting in frequent maloperation of traditional pilot zero-sequence directional protection. First, the performance of traditional zero sequence directional protection is analyzed from three aspects: sensitivity, weak current and strong magnetism and crossline fault, and the existing problems are pointed out. Then, a novel pilot zero-sequence directional protection scheme is proposed. A zero-sequence directional voltage compensation algorithm is used to enhance the sensitivity of zero-sequence directional elements under high resistance faults, and zero-sequence integrated directional elements are used to eliminate the influence of zero-sequence mutual inductance. Thus a cross-line fault identification logic is constructed. Finally, the effectiveness of the proposed algorithm is verified by three field examples. This work is supported by Youth Fund of National Natural Science Foundation of China (No. 51507050) and Young Elite Scientists Sponsorship Program by CSEE (No. CSEE-YESS-2017).