屏蔽泄漏变化对电压互感器串联加法的影响研究

Research on the influence caused by shielding leakage variation on the method of series summation for voltage transformers

电压互感器串联加法是国家工频电压比例标准体系量值溯源的重要理论及基础。串联加法测量过程中上级互感器的工作电位发了变化,高压条件下,初级高压绕组与屏蔽间的电势差变化导致泄漏电流发生改变,从而给测量结果带来影响。计及屏蔽泄漏的影响,文章对串联加法重新进行推导,理论分析由屏蔽泄漏带来的测量误差,同时提出一种改进方法,巧妙地将泄漏误差等值带入,使泄漏在整个测量过程保持不变。最后对改进方法进行了测试与验证,测试结果表明:改进前后测量结果的差异较明显,比差最大偏差为4. 6 ppm,角差最大偏差为5μrad,且改进后的测量结果与国际常用的电容器电压系数法更加接近。

The method of series summation for voltage transformers is an important theory of the traceability of the national power frequency voltage proportional standard system. The working potential of the upper transformer changes during the series summation measurement process. In the condition of high voltage, the difference of the potential between the primary high voltage winding and shielding leads to the change of leakage current. The measurement results will also vary. Considering the influence of shielding leakage, this paper re-deduces the series summation method and analyzes the measurement error caused by shielding leakage theoretically. Moreover, this paper proposes an improved method, which brings the leakage error into the measuring process equivalently and skillfully. In this way, the leakage remains unchanged throughout the measuring process. The improved method is tested and validated in the end. The test results show that the maximum deviation of specific deviation is 4.6 ppm for ratio error and 5 urad for phase error. The improved measurement results are closer to the method of capacitor voltage coefficient that commonly used worldwide.