Novel method on interharmonics detection based on SSI and LS

A novel method of high-accuracy detection for interharmonics based on stochastic subspace identification(SSI) and least square technique(LS) technique is proposed.SSI is used for modal parameters identification of linear system in time-domain. Firstly, Hankel matrix is built by using the output data of system, then system matrix and output matrix of system state equation are separated, so system modal parameters(inherent frequency, damping ratio and mode shape of variation) are identified. Frequency, attenuation factor and amptitute of interharmonics can be detected by SSI and the automatic ranking of system can be realized based on the mode shape of vibration, and phases of each frequency component of interharmonics can be estimated based on LS furthermore. Numerically simulating signals of noise, fluctuating frequency and fluctuating amplitude, and variable-frequency-speed-regulation system's current are analysed based on SSI and LS, and contrasting to Prony method, high accuracy and anti-noise ability of t