基于能量分布的特高压直流输电线路雷电暂态识别方法

Lightening Transient Identification Method for Ultra High Voltage Direct Current Power Transmission Lines Based on Energy Distribution

特高压直流输电线路雷击引起的暂态信号高频分量,是行波保护和暂态保护误动的主要因素之一。输电线路在雷击故障和普通接地短路故障下,因有故障电流入地通路,保护安装处检测到的电压信号的幅值会快速衰减,信号复杂度低;在雷击未故障情况下,不存在故障电流入地通路,保护安装处检测到的电压信号的幅值衰减较慢,信号复杂度高。研究基于多尺度小波变换分析了电压信号频率分量的衰减,用小波能谱熵反映电流或电压频率空间的能量分布信息,实现雷电暂态信号的识别,并通过能量相对熵实现故障极的选择。在EMTP/PSCAD中搭建了±800 k V直流输电模型,仿真结果表明,方案能很好地进行暂态信号的识别,受故障距离、过渡电阻等因素的影响小。

Transient signal high-frequency component caused by lightning strokes on ultra high valtage direct current transmission lines is one of the main causes for the malfunction of travelling wave protection and transient protection. In the case of lightening stroke fault or normal grounding short circuit fault of the transmission line,as the fault current has a grounding passage,the voltage amplitude detected at the protection installation attenuates quickly and the signal complexity remains at a low level. If the lightening stroke does not cause any failure,there is no grounding passage for the fault current,the voltage amplitude detected at the protection installation will attenuate slowly,and the signal will have a high complexity. This paper analyzed the attenuation of the frequency component of the voltage signal on the basis of multi-scale wavelet transform. Energy distribution information of current or voltage frequency space was reflected by the wavelet energy entropy to realize identification of lightening transient signal,and faulty poles were selected through relative entropy of energy. A ± 800 kV DC power transmission model was set up in EMTP/PSCAD. Simulation results indicated that the proposed approach could make good identification of transient signal,under little influence of fault distance,transition resistance and other factors.