TWO-LEVEL STATIC STATE ESTIMATOR FOR ELECTRIC POWER SYSTEMS.

A hierarchical concept is used to solve the static state estimation problem for large-scale composite power systems. The solution is obtained by performing a two-level calculation. In the lower level, a conventional state estimation is carried out simultaneously for all subsystems. The coordination of these local estimations is realized in the upper level. One of the main contributions of the paper lies in the construction of an appropriate second-level algorithm. Its suitability and also the main features of the overall procedure are then explored and illustrated on the basis of the Belgian 380-220-150 kv transmision network. Comparisons with the standard ″integrated″ state estimation are also performed.