Real and reactive power analysis for interharmonics

Due to the non-harmonic nature of interharmonics, power flow analysis associated with interharmonic frequencies has not been intensively studied. Hence, we propose the use of the cross power spectrum technique for interharmonic power analysis. The cross power spectrum allows one to determine the magnitude and direction of real and reactive power flow at every frequency of interest. Therefore, the method appears to be an appropriate tool for interharmonic power analysis. The efficacy of the proposed method is demonstrated through an investigation of voltage and current waveforms from a simulated current source type inverter drive system based on ATP-EMTP. It is shown that power flow associated with interharmonic events can be better understood in a quantitative manner with the use of the cross power spectrum method.