A decomposition and coordination power system loss calculation for multi-area interconnected system

In order to realize hierarchical and distributed computation and keep results consistent, a decomposition-coordination approach is needed in large scale power system loss calculation. This paper proposes a simple and practical two-level algorithm. Firstly, the interconnected power system is divided into several overlapped subsystems. The boundary buses with measurement data, which belong to neighboring subsystem, constitute a boundary region. With the idea of state estimation, the power system loss calculation model is established. Then, the KKT(Karush-Kuhn-Tucker) condition equations of the problem are divided into two kinds of subsets naturally. One is regional state estimation, and the other is coordination equation of boundary region. With the given boundary state and considering the known measurements type, the former equation can be solved by the traditional power flow algorithm. Then, if the error condition of coordination equation is satisfied, the whole power system loss calculation is finished. Otherwise, the result of coordination equation is used to modify boundary buses state in subsystem. The algorithm is implemented and tested using a real power system. The result indicates the validity of the approach.