频域灵敏度及其在电力系统参数辨识中的应用

Frequency-domain Sensitivities With Application to Power System Modeling

在以往的电力系统参数辨识研究中,灵敏度分析都是在时域进行的。分析和实践表明,时域灵敏度分析并不能完全地区分重要参数与次要参数,有可能出现时域灵敏度大但参数辨识误差也大的情况。定义几个频域灵敏度指标,提出计算频域灵敏度的2种数值方法,即基于传递函数的计算方法和基于傅氏变换的计算方法;指出要得到参数辨识的精度和难易度,需要综合分析时域灵敏度、频域灵敏度、功率谱等因素;推导基于电流变量的电力负荷传递函数模型。通过IEEE9节点系统算例进行频域灵敏度和时域灵敏度分析,并获得了有意义的结果。

The sensitivity analysis for parameter estimation in power system was generally studied in time-domain. However, the key parameters can not be completely distinguished only through the time-domain sensitivity. For example, it occurs the situation very possibly that the time-domain sensitivity is large and so is the parameter error. The frequency-domain sensitivity was defined. Two methods were developed for calculating the frequency-domain sensitivity, i.e. an analytical method based on the transfer function and a computational method based on the Fourier transformation. It was pointed out that the parameter estimation accuracy depends on factors such as the time-domain sensitivity, the frequency-domain sensitivity and the power density function of measurements. A transfer function model was developed for the composite power load with currents as state variables. Through case studies on IEEE 9-bus system, both the frequency-domain sensitivity and the time-domain sensitivity were analyzed, and some valuable results were obtained.