Influence and Dominant Factors Determination of Errors in the Parameter Identification of Three-Winding Transformer with PMU Data

Abstract

AbstractThe online identification of transformer parameters is influenced by the measurement errors, and engages deviations which could deteriorate the analysis and control of power system. However, the characteristics of influence of error are unknown. This paper presents the influence of measurement error and transformer ratio on identified transformer parameter, and determines the dominant factors, with the sensitivity analysis. Specifically, first, the parameter identification method for transformer based on the three-winding equivalent model is presented and simulated. Secondly, the analytical and approximate calculation methods for the sensitivities of the identified parameters with respected to the phase angle and amplitude measurement error, and transformer ratio error are introduced. Thirdly, with simulations, the correctness of the sensitivity analysis and approximate calculation results are verified. Furthermore, the characteristics of the different sensitivities are compared. Finally, with the characteristics of the sensitivities, the dominant factors for the identified transformer parameter are determined. That is, the dominant factors for the identified resistance are the errors of voltage phase angle and amplitude, and ratio of high-middle voltage side. The dominant factors for the identified reactance are errors of voltage amplitude and phase angle, and errors of ratio of high-middle voltage side and high-low voltage side. For example, when the voltage amplitude measurement error is 1%, the relative error of the identified resistance and reactance can reach more than 5000% and 20% respectively.KeywordsThree-winding transformerParameter identificationSensitivity analysisDominant factorsPMUData errorInfluence characteristics