电缆渗水缺陷模型及识别波形特征研究

电缆长期处于潮湿地下环境中,外部水分会渗入电缆内部引发绝缘故障,因而电缆渗水缺陷的研究至关重要。为实现电缆渗水缺陷精准定位,构建电缆中间接头及渗水缺陷模型,通过PSCAD搭建电缆传输线路计算模型,根据不同阻抗点特征波形分辨渗水缺陷;对含渗水缺陷电缆进行仿真,根据时域反射(TDR)定位原理确定渗水缺陷位置,并通过渗水缺陷定位试验进行验证。结果表明,TDR检测电缆渗水缺陷时会产生独特的反射波形,该波形与渗水缺陷在电缆中位置无关,但会因渗水量的不同改变其幅值与振荡频率,从而分辨出缺陷,达到精确定位的目的。

Study on Model of Cable Water Seepage Defect and Identification Waveform Characteristics

When the cable is in the damp underground environment for a long time,the external water will gradually infiltrate into the internal to cause the cable insulation failure.In order to achieve the precise positioning of cable water penetration defect,this paper builds the cable intermediate joint and water penetration defect model.The calculation model of cable transmission line was established on PSCAD platform.According to the characteristic waveform of different impedance point,water penetration defect was discriminated.The containing water penetration defect cable was simulated.The principle of time domain reflection positioning is used to determine the water penetration defect location,and the defect location of water seepage of relevant tests have been carried out.The results show that the TDR will produce a unique reflection waveform when detecting cable water seepage defects.The waveform has nothing to do with the position of water seepage defect in the cable,but it will change its amplitude and oscillation frequency due to different water seepage.Therefore,the defect has been distinguished,and the defect’s position is determined accurately.