Grid equipment parameter error identification based on mean algebraic sum of branch measurement normalized residuals

According to the normal distribution of random measurement error, a method of parameter error identification is applied for grid equipment, which is based on the mean values of its PMU or SCADA measurements for multiple periods. Based on the equivalent circuit model of transmission line, double- winding transformer and three-winding transformer, and together with their PMU or SCADA measurements, a comprehensive normalized value residual index of single equipment for the same period is presented, which comprehensively reflects the influence of both measurement error and parameter error on the residuals. With the variance coefficient as the convergence condition, the absolute mean value of the algebraic sum of comprehensive residuals for multiple periods(index T) is obtained, which mainly reflects the influence of parameter error on the residuals. According to index T, the parameter error of the device is identified. The identification method based on the mean square sum of comprehensive residuals presented in the reference is analyzed and the advantages of the proposed method in the elimination of measurement error influence and the determination of sample size are introduced. Its effectiveness is verified by simulative analysis.