针对参数估计值受量测误差影响而随机变化的问题,基于三绕组变压器三侧的相量测量单元(PMU)或数据采集与监控(SCADA)系统多时段量测信息,提出了变压器电抗参数的抗差估计方法.首先,以变压器三侧的支路电流向量、中性点电压及电抗参数为状态变量,建立三绕组变压器的多时段PMU或SCADA量测方程及对应的增广最小二乘电抗参数估计模型,并采用高斯牛顿法求解.其次,以变压器电抗参数的最小二乘估计值为样本,以随机样本的方差系数门槛值为收敛判据,迭代计算变压器电抗参数最小二乘估计值的均值,并将其作为最终的参数估计值.由于采用均值估计方法并选择了合适的均值样本数,因而文中所述方法具有明显的抗差性优势.考虑典型500 kV三绕组变压器的不同负载水平,仿真分析了其最小二乘参数估计值的随机变化特点,同时验证了文中模型和方法的有效性.%Considering the problem of randomly changing estimated parameter values with the impact of measurement errors, a robust method for transformer reactance estimation is presented based on phasor measurement unit (PMU) or supervisory control and data acquisition (SCADA) system multi-period measurement information of three-winding transformer at three sides. Firstly, the transformer three sides' branch current phasor, neutral point voltage and reactance are regarded as state variables, the paper establishes the three-winding transformer multi-period PMU or SCADA measurement equations and corresponding extended least squares reactance estimation model, which can be solved by Gauss-Newton method- Secondly, the least squares estimated values of transformer reactance is regarded as the sample and the variance coefficient threshold of random sample as the convergence criterion, the average value of the transformer reactance's least squares estimated value by iterative calculation is obtained as the final estimated parameter values. Because the average estimation is used and the proper average samples are chosen, the proposed method has excellent superiority in robustness. With different load levels of a typical 500 kV three-winding transformer, the random characteristics of its parameter values obtained by least squares estimation is analyzed. The model and method proposed are also verified.
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