Research progress in dynamic security assessment

Abstract

Progress achieved during a three-year research effort in power-system security assessment is discussed. The areas discussed are: power-system modeling, state estimation, structure decomposition, state forecasting, clustering and security measure development. A detailed dynamic model of a multimachine power system has been developed. The model includes the effects of stochastic load variations and possible transmission line and/or generator outages. A process state estimator was developed to estimate the long-term dynamic behavior of the power system. The algorithm is in a form identical to the extended Kalman filter but has a modified process noise driving term. A two-stage structure estimation technique was proposed for identifying the power system network configuration from available measurements. Two approaches to structure decomposition were investigated. A time-scale decomposition of the system equations, based on a singular perturbation approach, was evaluated using a detailed model of a generating system. This approach to system order reduction was extended to the process state estimation equations. Spatial decomposition was examined by applying an optimal network decomposition technique to a 39-bus test system. Stochastic approximation based approaches to estimator simplification were examined. Explicit expressions were obtained for the evolution of the first and second moments of the system state which take intomore » account the possibility of changes in system network configuration. Clustering criteria were developed for use in reducing the number of system disturbances that must be considered.« less