基于暂态零序电压-零序电荷时频相关性的配电网单相接地故障选线方法

Fault Line Selection of Distribution Network Based on Time-frequency Correlation of Transient Zero-sequence Voltage-charge

谐振接地系统发生单相接地故障时,健全线路的暂态零序电压和零序电荷呈线性关系,故障线路的则不满足线性关系,据此提出一种利用暂态零序电压和零序电荷时频相关性的配网接地故障选线方法。该方法利用各线路故障后半个工频周期的暂态零序电压和零序电荷数据,经小波包分解和重构,得到各频带重构系数,将各频带系数等分为多个时频小块,进而求得时频矩阵。通过比较暂态零序电压和零序电荷的时频矩阵相关系数形成选线判据。大量仿真结果表明,该方法准确、可靠。

For single-phase grounding faults in resonant earth systems, the zero-sequence voltage is linear with the zero- sequence charge in healthy lines while there is no linear relationship in fault lines. A new approach based on the time- frequency correlation of transient zero-sequence voltage-charge was presented to detect the fault line in distribution net- work. The fault transient zero-sequence voltage-charge data of each lines are extracted for the last half of power cycle, which are then decomposed by the wavelet packet and reconstructed into different frequency bands. All frequency bands coefficients were divided into several time-frequency pieces which had the same time interval. The time-frequency matrix be obtained by calculating the amplitude of time-frequency pieces. Faulty line is detected by comparing the time-frequen- cy matrix correlation coefficient of transient zero-sequence vohage-charge. A large number of simulation results show that the proposed approach is accurate and reliable.