直流叠加交流电压下交联聚乙烯中电树枝特性研究

摘要

电树枝在直流电压和交流电压下具有明显不同的引发和生长特性.为了研究直流电缆系统中直流成分和交流成分对电树枝特性的影响,该文研究了直流叠加交流电压情况下电树枝的引发和生长特性.研究结果表明,交流分量的引入极大地降低了电树枝的引发电压,并使得电树枝的生长速度较单纯直流电压下大大增加.直流叠加交流复合电压下电树枝的引发主要受交流分量的影响,而直流电压对其影响较小.负极性直流偏置电压下,电树枝主要为双结构的松枝状树枝,生长速度较慢,且直流电压的增大并未对其生长速度造成明显影响;而正极性偏置电压下,电树枝分支较少,生长速度较快,生长速度随着电压的增大而迅速增加.实验结果表明直流电缆系统中若存在较大的交流分量,将对直流电缆系统的绝缘安全构成较大威胁.%The initial and growth properties of electrical trees under DC and AC voltages are quite different.In order to investigate the influences of DC and AC components in HVDC cable system on the electrical tree properties,the initial and growth properties of electrical trees under DC and AC composite voltages were studied in this paper.The results showed that the introduction of AC component greatly reduced the DC tree inception voltages and the growth rate increased significantly compared to that under pure DC voltage.The initial properties of the electrical tree were mainly affected by the AC component,and the DC voltage had little influence on the initial properties.The electrical trees were mainly pine-branch type with a relatively slow growth rate under negative DC bias voltages.Besides,the increase of the negative voltage had little influence on the growth rate of the electrical tree.In contrast,the electrical trees were mainly branch type with a relatively faster growth rate under positive DC bias voltages and the growth rate of the electrical tree increased rapidly with the increase of the voltage.The test results indicated that the insulation safety will be threatened if there is a larger AC component in the HVDC cable system.