Analysis Of Measurements Influence On Power System State Estimation

With the increasing of the power system network, the accuracy requirement of the power system state estimation gets higher and higher. The accuracy of the power system state estimation will affect the decision-making power system analysis and control.So it is necessary to analyse the precision of state estimation.This thesis makes a thorough study on the state estimation theory and three kinds of classical algorithms. It focuses on the analysis of the measurements error on state estimation precision, and studies the weight set of the measurements. Setting reasonable weight is very helpful for improving state estimation accuracy, The traditional method of measuring the weight is generally to select the reciprocal of the variance of the measurement error as weights, which does not consider the different types of measurements for state estimation precision effects. This thesis makes a thorough study and discuss on how different types of measurements affect the accuracy of state estimation. The example analysis showed that measurements have effects on state estimation, and the setted weight is rational.Through analysis, the affect of branch power on the accuracy of state estimation is smaller than the nodal injection power, the node voltage and phase angle.Therefore, when setting the weight, the weight of the branch power is setted larger, corresponding to the nodal injection power, node voltage and phase angle smaller weights. The weight of nodal injection power is based on the number of outlets. Setting the reasonable weight can greatly improve the precision of state estimation.This thesis uses the weighted least squares method for the example analysis of4node system. Firstly the power flow calculation results are regarded as the value. Then, we respectively set errors of measurements, and the error values can be obtained. By simulating IEEE30system, an improvement of the weights setting method for measurements is made out, which can verify the correctness of the theory analysis and the setted weight is reasonable.