低频电压下XLPE电树枝生长及局部放电特性

Propagation and partial discharge characteristics of electrical tree in XLPE cable insulation under low-frequency AC voltage

低频电缆作为柔性低频交流输电系统中的关键设备,其绝缘介质在低频电压下的特性对电缆的设计和运行具有重要意义。为了研究低频电压下交联聚乙烯(XLPE)电树枝的生长及局部放电特性,设计并搭建了不同频率下电树枝生长实时观测和局部放电同步测量系统,探究了XLPE试样分别在20、30、40、50 Hz频率下电树枝的引发、生长及局部放电特性。结果表明:电压频率对XLPE电树枝生长及局部放电特性的影响有明显规律性。在20~50 Hz范围内,随着频率的降低,XLPE的起树电压略有升高,但电树枝生长速度加快,损伤面积增加,局部放电量和放电次数增大,放电相位分布基本不变。

Low-frequency cable is a key equipment in the flexible low-frequency AC transmission system,and the characteristics of insulation medium under low-frequency voltage are of great significance to the design and operation of cable.In order to study the growth and partial discharge characteristics of electrical tree in cross-linked polyethylene under low-frequency voltage,a real-time observation system for electrical tree growth at different frequencies and a synchronous measurement system for partial discharge were designed and constructed.The initiation,growth,and partial discharge characteristics of electrical tree in XLPE samples were investigated at four frequencies of 20,30,40,and 50 Hz.The results show that the influence of voltage frequency on the growth and partial discharge characteristics of electrical tree in XLPE has obvious rules.In the range of 20−50 Hz,with the decrease of voltage frequency,the tree starting voltage of XLPE increases slightly,but the growth rate of electrical tree is accelerated,the damage area increases,the amount and number of partial discharge increase,and the partial discharge phase is basically unchanged.