The error

caused by power system harmonics

in measuring resistive current of metal oxide surge arrester can be lessened by improved capacitive current compensation method.And resistive current of MOA can be acquired effectively in synchronous sampling.DFT has spectrum leakage and fence effect during asynchronous sampling

which influence the accuracy of measured resistive current of MOA.For resolving this problem

modified capacitive current compensation method based on Hanning-windowed interpolation is proposed in this paper.The error of resistive current

caused by asynchronous sampling

is decreased effectively

and the reliability of MOA fault diagnosis based on fundamental harmonic and third harmonic of resistive current is improved.Effectiveness of the proposal algorithm is verified by the simulation analysis result.