中压交联电缆接头复合界面受潮缺陷的诊断方法研究

Study on Diagnostic Method of Compound Boundary in Medium Voltage Cross-linked Cable Joints Moistened

电缆中间接头复合界面受潮是中压交联电缆的常见缺陷,在运行的过程中会导致界面表面电阻下降,进而产生沿面放电,逐渐降低电缆的绝缘性能,甚至直接导致电缆中间接头绝缘击穿事故,给电缆线路的安全稳定运行带来严重隐患。笔者根据电缆中间接头的结构特征建立了复合界面受潮缺陷的等效电路模型,仿真分析了不同程度受潮缺陷下,注入脉冲信号的时域反射波形图谱及其典型特征。提出了一种采用基于注入脉冲信号时域反射波法检测与定位电缆中间接头复合界面不同程度受潮缺陷的方法,并通过工业应用案例验证了该方法的有效性。

As the main problem of MV XLPE cable,the compound boundary in MV XLPE cable joints moistened reduced the surface resistance which will lead to creeping discharge and cause a sharp decline in insulation performance, and may make joints breakdown. These hidden troubles affect the safe and stable operation of XLPE cable. Based on the compound boundary of the cable joint, this paper has established the equivalent circuit model. Simulation analyses characteristics of time-domain of wave reflection in the different degree of the joints moistened by injecting pulse signal. This paper proposes an approach to detect and locate the cable intermediate joint composite interface be affected with different degree of the joints moistened based on the injection pulse signal time domain reflection wave. The effectiveness of the proposed method is verified by practical engineering testing.