Predicting the risk of DC-bias in Sichuan Province during ±800kV Binjin UHVDC transmission system joint debugging based on the finite element method

摘要

This paper analyses the research methods of DC bias, compares the advantages and disadvantages of various domestic and international analysis method, and puts forward that the multi physics modeling method based on FEM is the most reliable and most accurate method of analyzing DC bias. This paper simulates the phenomenon of DC bias in Sichuan province during Binjin DC system joint debugging based on the finite element method. The result shows that the method's error is less than 10 percent in simulating earth potential distribution, main transformer neutral current and DC current in AC systems under the condition of ignoring the local geological structure of the local area. Through this research, we can accurately predict the risk of DC bias of multiple DC transmission lines in Sichuan province, which runs in various earth return running mode such as unipolar maintenance, unipolar latching, and bipolar asymmetry. And the study makes suppression measures as well, which plays a very important role in the safe and stable operation of power equipment.