Partial discharge test on a transformer is carried out according to the items in IEC 60. During the test, unproved measuring system is calibrated by proved system at a voltage no less than 50% the rated testing voltag...Partial discharge test on a transformer is carried out according to the items in IEC 60. During the test, unproved measuring system is calibrated by proved system at a voltage no less than 50% the rated testing voltage. The result is then extrapolated linearly, leading to an error related to the distribution of stray capacitance, which varies with the testing frequency, especially to large transformers. In this paper a factor, named the capacitive rise fact, is introduced to assess the rise. The factor can be adjusted to some extent by changing the reactance that is connected to the LV side of the testing circuit to lower the capacity of the power source. However, the factor changes when the voltage divider on the high voltage side is removed after the voltage ratio has been calculated, and a great error is resulted under unfavorable conditios.展开更多
我国特高压交流变压器局部放电试验的电源大多采用中频发电机组,具有配套装置多、笨重不便操作等缺点。为此,提出了一种基于调频式谐振特高压试验电源(UHV-FTRTPS)的特高压交流变压器局部放电试验方法。该方法试验电源的功率放大器件主...我国特高压交流变压器局部放电试验的电源大多采用中频发电机组,具有配套装置多、笨重不便操作等缺点。为此,提出了一种基于调频式谐振特高压试验电源(UHV-FTRTPS)的特高压交流变压器局部放电试验方法。该方法试验电源的功率放大器件主要为模拟功率放大器,通过计算与分析高压补偿电抗器的损耗、试验电路的附加损耗、被试特高压交流变压器空载损耗、中间升压励磁变压器损耗得出试验电源的总容量,并以减少试验回路总损耗为目标,确定了试验电源输出电压信号的频率调节范围;同时依据被测试特高压交流变压器现场加压时间和步骤,提出了中间励磁升压变压器台数及档位的2种选择方式;针对试验过程中试验电源输出电压信号中出现的自激振荡干扰和电磁干扰,提出了增加信号屏蔽措施和RC输出滤波器的解决方法。依据理论分析和计算得出了试验电源的总容量≥600 k W,确定了试验电源输出电压信号的频率调节范围为140~155 Hz。现场试验结果表明,被测试特高压交流变压器的局部放电量≤500 p C,验证了提出的局部特高压交流变器局部放电试验方案的正确性、有效性。展开更多
文摘Partial discharge test on a transformer is carried out according to the items in IEC 60. During the test, unproved measuring system is calibrated by proved system at a voltage no less than 50% the rated testing voltage. The result is then extrapolated linearly, leading to an error related to the distribution of stray capacitance, which varies with the testing frequency, especially to large transformers. In this paper a factor, named the capacitive rise fact, is introduced to assess the rise. The factor can be adjusted to some extent by changing the reactance that is connected to the LV side of the testing circuit to lower the capacity of the power source. However, the factor changes when the voltage divider on the high voltage side is removed after the voltage ratio has been calculated, and a great error is resulted under unfavorable conditios.
文摘我国特高压交流变压器局部放电试验的电源大多采用中频发电机组,具有配套装置多、笨重不便操作等缺点。为此,提出了一种基于调频式谐振特高压试验电源(UHV-FTRTPS)的特高压交流变压器局部放电试验方法。该方法试验电源的功率放大器件主要为模拟功率放大器,通过计算与分析高压补偿电抗器的损耗、试验电路的附加损耗、被试特高压交流变压器空载损耗、中间升压励磁变压器损耗得出试验电源的总容量,并以减少试验回路总损耗为目标,确定了试验电源输出电压信号的频率调节范围;同时依据被测试特高压交流变压器现场加压时间和步骤,提出了中间励磁升压变压器台数及档位的2种选择方式;针对试验过程中试验电源输出电压信号中出现的自激振荡干扰和电磁干扰,提出了增加信号屏蔽措施和RC输出滤波器的解决方法。依据理论分析和计算得出了试验电源的总容量≥600 k W,确定了试验电源输出电压信号的频率调节范围为140~155 Hz。现场试验结果表明,被测试特高压交流变压器的局部放电量≤500 p C,验证了提出的局部特高压交流变器局部放电试验方案的正确性、有效性。
