±500kV电子式直流电流互感器集肤效应分析

Skin Effect Analysis of Electronic Current Transformer in ±500kV

介绍了用于高压直流电流测量的电子式直流电流互感器,针对其中关键部分——分流器,深入分析了集肤效应的影响。正常情况下在高压直流线路中,流过分流器的电流为直流,但过渡过程及不可避免的干扰会产生一定的谐波电流,由此引起的集肤效应可能会对测量和保护产生影响。本文在理论分析的基础上,结合自行研制的样机和贵州—广州±500kV线路采用的西门子公司的直流电流互感器及其实际挂网试验证明:采用鼠笼结构的分流器,3kHz以下的谐波电流,其集肤效应不会对测量和保护产生影响;对3kHz以上的谐波电流,分流器的集肤效应影响大,必须严格控制谐波电流以保证分流器的性能,同时可在二次电路中进行滤波处理以保证测量和保护的准确性。

This paper briefly introduces an electronic current transformer for high-voltage direct current measuring application. An in-depth study about the influence of the skin effect of shunt ,which is key parts of transformer, is made. Normally at the high-voltage direct current lines, the current flow into shunt is DC, but the transition process and inevitable interference would produce a certain harmonic currents, as a result, the skin effect may have an impact on the protection and measurement. With the theoretical analysis and the actual operating experience of electronic current transformers which are self-developed and made by Siemens Co. Ltd using at Guizhou-Guangxi ±500kV high-voltage direct current lines, this paper show that using cage structure of the shunt, for the harmonic current below 3kHz, the skin effect have no impact on the protection and measurement; for the harmonic current above 3kHz, the influence of the skin effect can not be ignored, to ensure shunt performance the harmonic current must be strictly controlled, accordingly, in the second circuit filtering must be used to ensure measurement and protection accuracy.