Hierarchical Control of Bifurcating Power Systems

{ A multilevel nonlinear control scheme with capability of operating over wide ranges is proposed. The rst control level connnes the system operation to some reference segments in its state space. On each reference segment, the required control actions are identiied through structural analysis of the (nonlinear) system which helps in exploitation of its qualitative behavior. The exploitation of the system structural behavior is used for further division of the reference segments. The operating sub-segments are modeled in terms of fuzzy sets and for each region the proper local control law is identiied. The variations of the control law on each reference segment are established as the average of local control laws weighted by the operating region membership functions. The approach is demonstrated for control of a bifurcating power system model as its loading level is varied.