A simple windowed interpolation fast Fourier transform (FFT) algorithm is proposed for power harmonic analysis under asynchronous sampling. The time and frequency domain characteristics of 5-term maximum-sidelobe-decay (MSD) window are analyzed first. Then an interpolation approach based on 5-term MSD window FFT is given and the formula of harmonics amplitude

initial phase and frequency are deduced. The approach presented is finally verified by simulations and experimental testing. Results show that the 5-term MSD window has satisfactory sidelobe characteristics for fully suppressing spectral leakage and the 5-term MSD window based interpolation method is easy to realize in embedded systems for its simple interpolated correction formula

closed form expression

highly accurate power harmonic analysis

and low computational burden. This work is supported by National Natural Science Foundation of China (No. 51177039).