Harmonic Braking-Based Optimization Scheme for Saturation Protection of Converter Transformer

This paper proposes an optimization scheme for converter current saturation protection based on harmonic ratio braking, which solves the problem of saturation protection action caused by inrush current. Saturation protection can effectively protect the converter transformer from the influence of direct current (DC) bias, preventing local overheating or insulation damage. When the converter transformer is under DC bias or inrush current scenarios, the method by setting the ratio or the change rate of the third harmonic to the second harmonic,can block saturation protection and prevent saturation protection action caused by inrush current,it also has certain application value for improving the reliability of saturation protection action. Simulation results verify the effectiveness of the proposed method.