A method for interharmonic measurement based on DQ transform and MUSIC algorithm

Along with the development of electric power system and the wide application of nonlinear equipments or devices, the harmonics in power networks become more complicated, and the interharmonics is more severe gradually. Dq transform and MUSIC algorithm is used to detect the frequency of interharmonics in this paper. The high amplitude fundamental waveform can be eliminated by dq transform. MUSIC algorithm is kinds of the subspace spectrum estimation methods having no requires for synchronous sampling, which is suitable for short-term stable interharmonic detection. Combination of both can effectively detect low interharmonic beside high amplitude fundamental waveform. The joint algorithm is robust when interharmonic-level noise is present. Finally, the amplitudes and phases of signal are estimated by the least squares method.