论文部分内容阅读
该文自主研发了一种以交联聚乙烯(cross-linked polyethylene，XLPE)为基体，添加0.5wt%纳米MgO颗粒的新型高压直流电缆绝缘材料。为研究不同温度下该材料中直流接地电树枝特性及其影响因素，对该材料和某商用级XLPE高压直流电缆绝缘材料进行了20~80℃下不同极性不同电压幅值的周期性直流接地电树枝实验。结果表明：电子比空穴更易注入，且在材料中拥有更大的平均自由程，因此负极性下电树枝比正极性下更易引发，且生长更为分散；纳米MgO的添加增加了材料中的陷阱密度，减弱了电荷注入，故纳米 MgO/XLPE 绝缘材料表现出更好的抗电树枝化性能；温度升高增强了电荷注入与脱陷，提高了电子平均自由程与电荷分布均匀度，使电树枝更容易引发和生长，且形态更加茂密。由此可见，电压极性与温度的改变，以及纳米MgO 的添加均会对材料中的周期性直流接地电树枝的引发与生长产生影响。“,”A new high voltage DC cable insulation material, based on cross-linked polyethylene(XLPE) and containing 0.5wt% nano-MgO, was developed independently. In order to investigate the characteristics of grounded DC tree and its influencing factors in this material under different temperatures. Periodic grounded DC tree experiments were conducted on this material and a commercial grade high voltage DC cable insulation material at 20~80℃ under different polarities and different voltage amplitudes. The results show that electron is easier to be injected than hole, and has larger mean free path in material, so the negative tree is easier to generate, and grows more dispersedly. The addition of nano-MgO increases the trap density in material, and weakens charge injection, so the nano-MgO/XLPE insulation material shows a better resistance to electrical tree. The increase of temperature enhances the charge injection and detrapping, and improves the electron mean free path and charge distribution uniformity, making the electrical tree easier to generate and propagate, and denser in shape. Thus it can be seen that the change of voltage polarity and temperature, and the addition of nano-MgO all have effect on the initiation and growth of periodic grounded DC tree.