不拆引线测量500 kV自耦变压器套管电容量及介质损耗的方法

500 kV自耦变压器体积庞大,套管高,拆除引线和接测量线都有困难。然而,自耦变压器高压套管、中压套管及中性点套管实为同一绕组连接,在低压绕组首尾短接接地的前提下,从中性点加测量电压、从套管末屏取试品电流来测量高压及中压套管电容量及介质损耗,可避免拆装引线和在高、中压套管上接拆测量线。通过对500 kV自耦变压器进行模型简化和等效电路运算,得出从中性点加测量电压测高压套管电容量及介质损耗的误差;并对广东省中山市500 kV香山变电站2台自耦变压器现场实测,验证了此种方法的可行性。

Measurements of Capacitance and Dielectric Loss of 500 kV Auto-Transformer Bushings Without Disconnecting Leads

In the measurement of 500 kV auto-transformer, it is difficult to connect and disconnect measuring lines to the transformer because of its large size and high placed bushings. However, the bushings at the ends of high- and medium-voltage and the neutral are connected by the same winding. If the low voltage winding is short-circuited and grounded, it is possible to achieve the values of bushings’ capacitance and dielectric loss by measuring neutral voltage and current from the bushing end without connecting or disconnect measuring lines. Through the computation of the simplified equivalent circuit model of 500 kV auto-transformer, the deviation of the capacitance and the dielectric loss of the testing bushing by using neutral voltage can be calculated. The proposed method is evaluated by using two 500 kV autotransformers in Xiangshan substation located in Zhongshan, Guangdong province, which demonstrates that the proposed method is effective and can be implemented in practice.