混合电力线路高频保护信号衰减计算方法

针对由多个传输介质组成的混合电力线路上高频保护信号衰减严重的情况,采用均匀传输线理论和传递矩阵法给出了混合电力线路信号衰减计算方法。结合由架空线路和埋地电缆组成的徐州220kV任贺线高频保护的信号衰减情况,分析了不同因素对单一介质线路上信号衰减的影响,并计算了任贺线混合电力线路的衰减曲线随频率的变化关系,结果表明其衰减特性随频率呈振荡变化趋势,混合电力线路的衰减最大值远大于同一长度的单一介质类型线路。通过试验测量了任贺线双回线上55kH z^200k Hz的载波信号衰减曲线,测量结果与理论计算结果基本一致,验证了计算的正确性。根据计算结果指导了高频保护的工作频率选取,更换频率后信号衰减显著降低。研究内容对分析混合电力线路的高频载波通信具有重要应用价值。

A Signal Attenuation Calculation Method of High Frequency Protection for Hybrid Power Lines

Aiming at the problem that high frequency protection signal transmission has serious attenuation on hybrid power lines composed of multiple media, a method for calculating the signal attenuation on hybrid power lines is proposed, using the theory of uniform transmission line and transfer matrix method. Based on signal attenuation of high frequency protection of 220kV Renhe Line in Xuzhou, Jiangsu, composed of overhead lines and buried cables, the influencing factors on signal attenuation in single medium are simulated and analyzed, and the changing relationship between Renhe hybrid line signal attenuation curve and frequency is calculated. Results show that the attenuation characteristics are oscillating with frequency, and the maximum attenuation for hybrid power lines is far greater than that for single medium line of the same length. The attenuation curves of 55kHz^200kHz carrier signal on Renhe double circuit line are measured by experiment, and the results basically coincide with theoretical calculation results, verifying correctness of the calculation. Based on the calculation results, the working frequency of high frequency protection is selected and the signal attenuation is significantly reduced after replacement of frequency. The researches in this paper have significant application value for analyzing the high frequency carrier communication of hybrid power lines.