In order to study the difference between static var generator (SVG) and static var compensator (SVC) and the practical application of SVG + FC comprehensive compensation system, this paper takes the power supply system of 35 kV substation in Wutongzhuang Mine as the research object, and transforms the original manual switching fixed capacitor compensation into a comprehensive dynamic reactive power compensation and harmonic control system. Through research and comparison, it is concluded that after the dynamic reactive power compensation device is put into operation, the influence of harmonics generated by the main shaft shunt motor, frequency converter and other equipment of the power supply system on the power quality is significantly reduced, the voltage fluctuation is effectively curbed, and the power factor and power quality are significantly improved, which provides a strong guarantee for the stable operation of transmission lines and power supply equipment.