特高压输电线路负序方向纵联保护

采用数字式二阶RC低通滤波器和半波差分傅里叶算法，结合相序变换滤取负序分量，可在微机保护中实现负序方向元件，并可在故障初几毫秒内正确动作。用该方法实现的负序方向元件可正确及时地捕捉到由不对称故障发展起来的三相短路故障瞬间的不对称，故可以反映各种不对称故障和由不对称故障发展起来的三相故障。仿真试验验证了用所提出的方法实现的负序方向元件用于特高压输电线路的可行性和优越性。

Pilot Protection of Ultra-high Voltage Transmission Lines with Negative Sequence Directional Component

In order to obtain the negative sequence component,this paper presents a novel algorithm,in which the digital second order RC low band pass filter is combined with the half-wave differential Fourier algorithm.By using microcomputers,a negative directional element is realized which operates during several milliseconds after fault initiation.As this directional element can also operate during unsymmetrical beginning period of three-phase faults,it can be used to detect different unsymmetrical faults and three-phase faults with short time unsymmetrical beginning.Simulation results show the effectiveness of the proposed method.