Analysis on the Influence of Remote 110kV Substation on Transformer DC Bias

Abstract

High voltage direct current (HVDC) transmission system has the advantages of large capacity, long distance and low loss. Relying on the advantages of HVDC transmission, China has established a large-scale energy transmission channel in the west, effectively solving the problem of uneven local energy distribution. However, HVDC transmission will generate ground current when it is operating in a single pole, which will cause the DC bias effect of the transformer. At this time, the core magnetic circuit of the transformer is saturated. Transformers will experience increased vibration, increased noise, local overheating, and surge in harmonics. This paper, based on the Jinhua HVDC transmission project as a background, established a power grid topology model in Zhejiang area based on the field-circuit coupling method. The focus is on calculating the DC bias of Shenze transformers in Jinhua area, and proposing treatment measures based on the calculation results. According to the actual measurement of the project, the accuracy of the calculation result is verified, which reflects the effectiveness of the governance measures.