考虑二次回路暂态传变特性的单端组合测距算法及其应用

Single-ended Assembled Fault Location Method and Application Considering Secondary Circuit Transfer Characteristics

故障点反射行波的准确辨识是单端行波测距的重要前提。由于现场中,故障测距装置必须通过由电流互感器、二次侧传输电缆以及二次侧负载组成的二次侧传变回路(简称二次回路)才能获得故障行波数据,因此必须首先分析二次回路的暂态传变特性。建立二次回路的暂态高频等效模型以及相应的传递函数,推导出二次侧行波波头衰减振荡的数学表达式,并通过数值计算的方法给出衰减振荡频率与二次侧传输电缆长度的关系。基于此,提出利用二进小波变换、Prony分解以及单端工频阻抗算法结合的单端组合测距方法;研发了相应的硬件装置,初步实现了现场的成功应用。该文的研究揭示了二次侧行波数据畸变的本质。同时,仿真结果和现场实际故障数据也验证了所提算法的精确性和实用性。

Identification and verification of the wave fronts is the precondition of single-ended travelling wave based fault location methods. The fault locators can obtain the data only from the secondary circuit which consists of the current transformer, the secondary cable and the secondary load. Therefore, transfer characteristics of the secondary circuit must be studied first. The high frequency model of the secondary circuit was built and the transfer function was obtained. The damped oscillation in the recorded traveling waves was explained. Based on the discovery, a single-ended fault location scheme involving an impedance fault location algorithm, the dyadic wavelet transform and Prony analysis was proposed in the paper. Relevant traveling wave fault locator was developed and implemented in a 220 kV substation. Recorded waveforms of a single-phase-to-ground fault has proved both the analysis and the location scheme. Abundant simulation results based on EMTP/ATP have also demonstrated the validity and improvement of the novel assembled single-ended fault location method.