Reduced order models for power system analysis

The development of two major reduction techniques which characterize slow speed dynamic phenomena is discussed. These reduced order models can be successfully applied to both linear and certain non-linear representations of a power system. A new approach to simplifying large linear dynamic systems is developed. A method of constructing a suboptimal control policy for a large system using the simplified model is developed. Three examples in the area of dynamic stability studies are considered to demonstrate the techniques developed. An approach to identifying coherent groups of generators is developed. The concept of coherency is developed from analyzing the eigenvectors of the linearized power system model. The concept of identifying coherent groups of generators is extended to include a more detailed model of a synchronous machine and its associated excitation and governing systems. By the modified definition of coherency, the coherent groups of the 39 bus sample test system are identified.