A novel online robust identification method for Xq of synchronous generator based on IGG criterion

This paper proposes a robust on-line identification method for the synchronous generator´s quadrature-axis synchronous reactance Xq with steady-state PMU (Phasor Measurement Unit) data based on the IGG criterion. Firstly, the mathematical formulation for identification of Xq, which is a least square estimation with the objective of terminal voltage fiting, is introduced. And then, the robust IGG criterion, which divides the measurement data into three types with different weight, i.e., retaining the weight of the effective measurement, reducing the weight of the available measurement, but refusing the harmful measurement is applied by modifying the objective function of the estimation. The proposed method could not only eliminate the effects of gross errors among measured data, but also resist the effects of bad data. Simulation results with BPA data and field PMU data verify the high accuracy and robustness of the proposed method in different cases.