Interharmonics monitoring of power network using modified covariance arithmetic and virtual instrument

This paper proposes a method of monitoring and analyzing interharmonics in power system based on modified covariance arithmetic and virtual instrument. The system consists of sensors, signal conditioning circuits, transfer boards, data acquisition (DAQ) and compute, which the parameters of interharmonics are identified by using the modified covariance arithmetic of AR model, Some essential issues, such as the spectrum distinguishing ability and the anti-noise ability of the algorithm, are researched, and the modified covariance arithmetic is applied to virtual instrument by using the MATLAB script node in LabVIEW. The simulation results show that by using the proposed method, the interharmonics near the integer harmonics can be detected accurately with higher anti-noise ability.