An M-class PMU Iterative Interpolated Algorithm Considering DC Offset

A phasor measurement unit (PMU) is a basic tool for synchrophasor estimation in modern power systems. The large-scale integration of power electronic devices in modern power systems results in DC offset on the AC side. In addition, with the rapid development of high-voltage DC transmission projects, the decay time of the DC offset in the system has further increased, which severely affects the estimation accuracy of the M-class PMU. When DC offset and out-of-band interference (OOBI) such as interharmonics coexist, the errors in the time-frequency domain convolution and higher-order matrix inversion increase. The errors of the M-class PMUs are further amplified as a result. Existing methods are ineffective in addressing this challenge. To address this problem, this paper proposes an algorithm based on polynomial fitting and three-point interpolation. First, the iterative elimination concept is employed to restructure DC offset. The initial estimation of the synchrophasor is subsequently performed via linear Bessel interpolation. Finally, the conditional iterative optimization is used for the second estimation of the synchrophasor. The simulation scenarios are designed based on Standard IEC/IEEE 60255-118-1, and the results show that the proposed algorithm can accurately estimate with OOBI and DC offset.