变压器直流偏磁抑制方法的应用分析

Application of Transformer DC Bias Restraining Methods

直流输电的入地电流可能导致交流电网内变压器的直流偏磁危害,因此采用合理有效抑制措施是保证交流电网安全运行的关键。对一随机生成的虚拟电网的直流偏磁抑制措施进行理论分析和数值求解,对中性点串联电阻/电容法的工作原理、实施方式、性能效果进行分析。对比2种方法的实现方式和技术参数,证明了采用抑制措施后,交流电网局部直流偏磁危害加剧,但电网直流电流总量下降,总体上直流偏磁风险下降。为了更有效地开展直流偏磁治理工作,提出了现代大型交流电网大范围采用中性点串联电阻/电容法抑制直流偏磁的实施原则。

For transformers in AC power grid, DC bias is caused by earth-return current of HVDC transmission. In order to restrain the adverse effect of DC bias, proper measures must be applied to ensure the safety operation of AC power grid. Based on the theoretical analysis and numerical computation of ordinary mitigation methods of DC bias, the mechanism, implementation and performance of these methods are revealed. Though local DC current of AC power grid rises, the total DC current in AC power grid decreases after mitigation method applied. For further application of neutral-series resistor/capacitor method, the implementation principle has been presented.