参数可观测性分析及其在电力负荷模型中的应用

Parameter Observability Analysis and Its Application to Power Load Model

给出了参数可观测性概念,指出如果输入激励的功率谱能够覆盖研究对象的振荡频率,则能够在输出信号中观测到这些振荡频率,从而也就可以观测到其对应的模式和参数。提出基于参数的功率谱灵敏度来定量分析参数可观测性,基于输出功率谱实测值与计算值误差平方和的最小化来优化辨识参数。以一个二阶系统为例,分析了输入激励类型、系统幅频特性尤其是系统阻尼对参数可观测性的影响。针对电力负荷传递函数模型,分析了负荷模型的频域特性,通过两种不同频谱分布的激励信号,验证了参数可观测性方法的正确性。

The concept of parameter observability is given,which indicates that if the power spectrum of input excitation can cover the oscillation frequency of the system,then the frequency can be observed via the output.So the corresponding modality and parameters can be identified.The power spectral sensitivity based on parameters is proposed to quantitatively analyze the parameter observability.Parameters are identified by minimizing the sum of square error between the measured and the calculated values of power spectrum.By taking a second-order system as an example,the factors of parameter observability are analyzed upon input excitation,the amplitude-frequency characteristic of system,especially the system damping.Finally,the frequency-domain characteristics of the power load model are studied,and the correctness of the concept proposed is verified by parameter identification using two different kinds of excitation signals.