基于最小二乘法的电力系统网络参数误差估计

Estimation of Parameter Errors in Power System Network Based on LeastSquare Method

为满足电力系统实时动态观测的要求,需要精确估计电网络参数,基于电力系统的任何网络参数误差都会影响状态估计中的量测残差,通过对量测残差的分析提出了一个基于最小二乘的电网络参数误差估计方法。分两步完成电网络参数误差的估计:首先根据动态系统的量测方程,利用加权最小二乘法(weighted least squares method,以下简称WLS),同时引入网络节点虚拟量测量作为等式约束条件建立最优化模型,利用拉格朗日乘法提出量测残差的表达式,网络节点虚拟量测量的引入加强了算法的精确性和收敛速度;第二步首先利用递推最小二乘建立量测残差方程中偏差项的的迭代公式,电网络参数误差包含在量测残差方程的偏差项中,通过迭代得出一个无偏估计的初始状态量,最后求得电网络参数误差。IEEE9节点系统的仿真验证了算法的正确性和有效性。

In order to serve the real-time dynamic power system observation, it is necessary to precisely estimate network parameters. Any error of network parameters in power system will affect the value of measurement residuals calculated in state estimation. An identification model of parameter errors in power system network based on the leastsquare method is proposed through analysis of measurement residuals. A two-step approach for parameter error estimation is introduced. The first step is that based on the measurement equation of the dynamic system, the virtual measurement of network node is introuduced as its constraint equations, the optimization model is established by using the weighted leastsquares method （WLS）, and the formulation of measurement residuals is proposed by using Lagrange mul- tiplication. The virtual measurement of network nodes will enhance algorithm accuracy and convergence speed. The second step is that the iterative formulation for a bias vector of measurement residuals is established with the recursive leastsquare method first, and parameter errors in network of power system are contained in bias vectors of measure- ment residuals. The initial state values are obtained, and pa- rameter errors are obtained at last. The simulation on IEEE 9 bus system proves that the algorithm is correct and effective.