Analysis of the Influence of Transformer Harmonics Caused by DC Bias on Reactive Power Compensation Capacitor Banks

The harmonics generated by the DC bias of the transformer will damage the reactive power compensation device connected to the low-voltage side. Based on the simplified core model of the transformer, this paper deduces the expressions of the excitation current and the output voltage of the secondary side of the transformer under the condition of DC bias, and analyzes the transmission mechanism of harmonics in the transformer. Based on the simulink tool in MATLAB, this paper calculates the harmonics of the excitation current and the excitation voltage during DC bias, and analyzes the influence of the bias current and the iron core saturation coefficient on the harmonic content. According to the specific configuration of reactive power compensation capacitors, the influence of harmonics on capacitors is analyzed.