Accurate calculation of system ground capacitive current is very important for precise compensation for self-tuning petersen-coil. In this paper

the power electronic switch is used to generate disturbed voltage and current containing plenty of frequency components by momentarily controlling its conduction state. The disturbance voltage and current signals are used to measure the ground capacitance in conjunction with the measuring method of harmonic impedance based on power electronic perturbation technique. The method is highly effective

and the impact on the working state of the arc suppression coil can be neglected. Simulation analysis and simulated experiment have proved the effectiveness of the method. This work is supported by Shandong Provincial Natural Science Foundation of China(No. ZR2013EEM026)and Shandong Provincial Key Science and Technology Program of China(No. 2015GGX104010).