An Elliptical Fitting Algorithm Based Detection Method for Reverse Power

In allusion to the reverse power detection of grid-connected irreversible-flow PV generation system, a reverse power detection method based on fitting algorithm of the ellipse parameters and delayed signal cancellation(DSC) is proposed. According to the different features of coefficient of elliptic equations under the occurrence of reverse power and grid fault, whether the reverse power or the fault was occurred can be rapidly detected and judged. The time-domain based DSC algorithm is adopted to eliminate the influence of power grid harmonics on the detection accuracy and real-time performance of the proposed algorithm. Results of both MATLAB/Simulink based simulation and actual operation show that the least square for fitting ellipses method and the proposed cascaded DSC algorithm can accurately distinguish reverse power from power grid fault around a cycle after the occurrence of the reverse power, and the proposed method possesses strong robustness for noise, and the proposed method is feasible.