Study On The Influence Of DC Magnetic Bias On Transformer In Taishan Plant In HVDC System

In order to solve our energy, load distribution is not balanced contradiction, to promote China’s west to East, mutual supply between South and North, nationwide interconnection power development strategy, DC transmission is playing a more and more important role. DC transmission has many advantages, such as long distance large capacity transmission, and can be easily connection. However, the HVDC mono polar ground circuit operation and bipolar unbalanced potential runtime difference will cause the phenomenon of transformer DC magnetic bias. This will affect the normal operation of the power station transformer, such as transformer magnetizing current caused by the harmonic distortion, increase, saturated iron core, magnetic flux aging of transformer insulation. Therefore, study on the caused by HVDC power of main transformer DC bias phenomenon is of great theoretical significance and engineering practical value.This paper studies the factors that lead to DC magnetic bias and the algorithm that calculate excitation current. A mathematical model on Taishan transformers was established and DC magnetic bias were simulated. Besides, this paper studies the influence of DC magnetic bias on main transformers nearby in HVDC system, analyses the effects of bias current on main transformers.This paper analyzes several common DC magnetic bias suppression method, and according to the Taishan power plant main transformer DC bias of transformer neutral point grounding resistance on DC biasing scheme, the 500kV main transformer neutral point connected resistor scheme to suppress the DC magnetic bias of feasibility study, the application of the effect was evaluated.