A distributed power system state estimator incorporating linear and nonlinear areas

The highly interconnected power systems require a robust distributed state estimator. Nowadays, many PMUs have been installed and some high voltage networks have already achieved PMU observable. However, many other areas are still PMU unobservable due to budget limitations. In PMU observable areas, the state estimation model is linear, while for the other areas, it remains nonlinear. This paper proposes a distributed state estimation method for solving the multi-area state estimation problems between linear and nonlinear areas. The relation between the objective function in the linear area and the boundary states has been derived as a linear function. By exchanging the linear function which contain the complete information in the linear area, the global optimal estimation can be achieved without any coordinate iterations. Consequently, the robustness and efficiency can be significantly enhanced.