State Estimation Study Based On Phasor Measurements

With the gradual development of national economy, the scale of power system is rapidly increased accordingly. Therefore, state estimation is regarded as an essential part of Energy Management System (EMS) due to the economy and security of power system. In recent years, GPS-based Phasor Measurement Units (PMU) have been successfully developed and equipped in power system. Thus, the novel mathematical model of state estimation based on PMU and the placement of them are proposed in this paper. The main tasks of the thesis are as follows:1.The phasor measurement technology based on GPS is introduced briefly. This paper also discusses the application of PMU in power system.2.On the basis of state estimation based on PMU in possession, a new model of state estimation is presented in this paper. The equivalent-current-based measurement transformation method is introduced first and then the rotational operator to the state and measurement functions result in the strict decoupling of the real and image part of normal equation. The algorithm can adequately utilize the information form PMU, including current phasor measurement. And it is also efficient, rapid and has small burden of storage. Furthermore, the precision improvement of state estimation due to incorporation of PMU is analyzed based on the model and particle swarm optimization (PSO) is applied to solve the placement of PMU. The results demonstrate that the model and algorithm are effective for practical use.3.This paper also presents a new algorithm of three-phase state estimation based on PMU by the decoupling compensation model that is used for three-phased load flow. According to the characters of iterate equation, the equation of three-phased state estimation can be decoupled strictly on phase coordinates, and with the rotation transformation added, the real and image part of normal equation can also be strict decoupled. Simulation test proves that this model is effective.