Analysis and Suppression of DC bias in Baihetan-Zhejiang UHVDC Transmission Project

Abstract

DC bias phenomenon is a serious threat to the electrical transformer in the power grid, which may cause abnormal vibration or overheat in some area of the transformer. The density of substations in Baihetan-Zhejiang UHVDC transmission project is high and some newly-built substations are close to Baihetan DC grounding electrode, there may have a DC-bias risk for electrical transformer. Therefore, the topology model of Baihetan-Zhejiang UHVDC transmission project is built and the distribution of DC bias current is calculated here. The suppression of the DC bias current measures is proposed based on the analysis of the distribution of DC bias current in Baihetan-Zhejiang UHVDC transmission project. To demonstrate the DC bias risk intuitively, a risk distribution map is defined, which can provide effective information for the construction of future substations in Baihetan district.