直流叠加冲击电压下XLPE中空间电荷特性研究

Study on space charge characteristics in XLPE under DC superimposed impulse voltage

高压交联聚乙烯(XLPE)直流电缆在工作状态下,会受到电力系统中由投切等操作引起的操作冲击电压的破坏,导致绝缘受到影响,而目前缺乏多次冲击累积效应引起空间电荷累积导致电缆绝缘劣化的相关研究。本文基于实验室已有的直流叠加冲击电压下的PEA法空间电荷测量系统,分别测量了直流电压、冲击电压、直流叠加冲击电压作用下XLPE电缆绝缘中的空间电荷特性。结果表明:正直流电压下XLPE体内以异极性电荷为主,负直流电压下SC电极上出现同极性负电荷的注入;连续的高幅值冲击电压作用会导致双电极上大量的同极性电荷注入,且负极性冲击下电荷注入量略多;当直流叠加冲击电压时,同极性叠加方式比异极性叠加方式更能促进双电极上同极性电荷的注入,而且冲击电压作用时间越长,XLPE试样内部积聚的电荷量越多。

HVDC cross-linked polyethylene(XLPE) cables will be damaged by operation impulse voltage caused by switching and other operations in the power system under working condition, which will affect the insulation. However, at present, there is a lack of relevant research on the cable insulation deterioration generated by space charge accumulation caused by multiple impulse cumulative effect. Based on the PEA space charge measurement system under DC superimposed impulse voltage in the laboratory, the space charge characteristics of XLPE cable insulation under DC voltage, impulse voltage, and DC superimposed impulse voltage were measured in this paper. The results show that XLPE is dominated by heteropolar charges under positive DC voltage, and negative charges of the same polarity appear on the SC electrode under negative DC voltage. Continuous high-amplitude impulse voltage can cause large number of homopolar charges injection on the two electrodes, and the amount of injected charge is larger under negative impluse voltage. Under DC superimposed impulse voltage, the same polarity superimposition method can promote the injection of homopolar charge on the two electrodes more than the opposite polarity superimposition method. Moreover, the longer the impulse voltage is applied, the more charge accumulates in the XLPE sample.