摘要
为了实现变频电源供电方式下的电流互感器局部放电试验,解决各类背景干扰问题,分析了高压大厅内辐射和传导干扰的波形和相位特征、电源回路与试验回路干扰的区别。通过对变频柜滤波、屏蔽改造以及高压试验装置无局放处理,采用单点接地与分开接地相结合以及平衡法检测回路,实现了整套装置的背景噪声的局部放电量<5pC,满足对500/220kV电流互感器的局放试验要求,并通过试验发现一处500kV倒立式油浸电流互感器绝缘缺陷。分析表明,经过降噪处理后,变频电源供电方式能获得常规工频电源等同的局放效果,其措施也可指导现场试验。
Interference must be removed in partial discharge test for current transformer supplied with variable-frequency power source, which has the merits such as small capacity, low cost, no magnetic saturation and so on relative to conventional power frequency source. In this paper, the waveform and phase features of both radiation interference and conduction interference in high-voltage hall are analyzed. When test is conducted, the phase angel of the interference come from experimental loop is invariable while the one come from power loop is variable according to power frequency. It was achieved that the background noise in the complete set of apparatus was less than 5 pC to satisfy the requirement of PD test for 500/220 kV current transformer by the measures including filtering for conversion cabinet in variable-frequency cabinet, reforming the shield, no PD disposal for high-voltage test facility, the combination of single-point grounding and multipoint grounding, and adopting the measuring circuit with balanced method. An insulation defect of 500 kV stand upside down type oil immersed current transformer was detected by testing with this method. After reducing noise, the equal PD effect could be obtained by supplying with variable-frequency power compared to conventional power source, and the methods could be used at locale test.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2009年第4期889-893,共5页
High Voltage Engineering
基金
国家电网公司重点科技项目(SGKJ[2007]892)~~
关键词
局部放电
抗干扰
电流互感器
变频电源
平衡法
接地
partial discharge
anti-interference
current transformer
variable-frequency power
balance method
grounding
