Affiliations: State Key Laboratory of Power Transmission Equipment & System Security and New Technology College of Electrical Engineering, Chongqing University, Chongqing, China
Correspondence:
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Corresponding author: Xingmou Liu, State Key Laboratory of Power Transmission Equipment & System Security and New Technology, College of Electrical Engineering, Chongqing University, Chongqing 400044, China. E-mail:liuxingmou@cqu.edu.cn
Abstract: Monopole operation model of Ultra High Voltage Direct
Current (UHVDC) system, DC bias has great influence on the safety and
stability of the system, especially for transformers, including temperature
rising and increased in vibration. However, there is less research have done
on increased vibration of transformer due to influence of DC bias on HVDC
system. This study explored transformer vibration caused by DC bias,
including the principle of transformer DC magnetic bias and the related
calculation method. The mathematical model of the electromagnetic force
coupling of the transformer core was also studied and after that its core
magnetic field and force field were analyzed. The displacement change of the
transformer core which included core clamps and fixed structures were
analyzed and discussed. Results revealed that the leakage flux of the clamps
increases with DC bias and odd harmonics appeared in each displacement
component. Specifically, the direction of the y displacement component
changed, and the maximum displacement occurred with the 90-degree phase
shift. Then, vibration experiment was done to analyze the DC bias
characteristic of core, which also valid the effectiveness of the built
simulation mode. Results indicate that amplitude and harmonics of the core
limb vibration increase greatly under DC bias condition. The research of
paper will also serve as references for addressing the vibration problems of
transformers under DC bias conditions.
Keywords: DC bias, transformer, vibration, coupling field
