直流XLPE电缆绝缘泄漏电流与局部放电试验特征研究

目前,直流电缆制造技术及工程空前发展,然而,国内外关于直流电压下XLPE电缆故障特征及劣化规律研究极少。局部放电和泄漏电流是电缆绝缘状态的两种重要表征手段。文中搭建了局部放电和泄漏电流联合检测试验平台,研究了绝缘内部气隙、主绝缘表面划伤以及金属毛刺电晕3种缺陷的局部放电和泄漏电流试验特征。结合理论分析及仿真,首先研究了放电量、放电重复率以及泄漏电流幅值间的相关性。之后,基于Shannon熵、互信息等分析手段,研究了不同极性电压下泄漏电流和施加电压间相关特征。综合来看,正常电缆、气隙缺陷、电晕缺陷在负极性电压下的泄漏电流-电压曲线,比正极性电压下的呈现更强线性相关性;划伤缺陷在正、负极性下的泄漏电流-电压间线性相关性均比较明显。该研究对电缆现场状态检测策略的研究具有重要价值。

Study on Experimental Characteristics of Leakage Current and Partial Discharge for DC XLPE Cables

At present,the manufacturing technology and engineering of DC cable systems has been developed quickly.However,there are few studies on the operation,fault characteristics and degradation of XLPE cables under DC voltage.Partial discharge and leakage current are two important characterization means of cable insulation.The joint test platform of partial discharge and leakage current is built.The characteristics of partial discharge and leakage current of three kinds of typical defects are studied.The defects are the air gap inside XLPE,the scratch on the insulation surface and the corona discharge.Combined with theoretical analysis and simulation,the correlations among the discharge capacity,discharge repetition rate and the leakage current amplitude are studied.After that,based on Shannon entropy and mutual information analysis,the correlation between leakage current and applied voltage is studied.In summary,the correlation between the leakage current and voltage of normal cable,air-gap defect and corona defect under negative voltage shows a stronger linear correlation than that under positive voltage.Both of the linear correlations between the leakage current and voltage under positive and negative polarity of scratch defects are obvious.Studies in this paper are of great value for cable status detection.