LAUSR

Summary An initialization of power system dynamic simulation using conventional power-flow model is not suitable for induction motor load due to unavoidable mismatch between prespecified reactive powers from power-flow calculation and the ones actually required by motor dynamic model. To eliminate the undesired mismatch, this paper presents a unified method for simultaneously solving power-network and motor variables in single frame of reference using Newton-Raphson algorithm for getting a good rate of convergence. An advanced inverse-Γ model of double-cage induction motors is newly developed to perform the initialization with minimum extra power-flow variables. An ability of the unified Newton-Raphson algorithm is demonstrated using IEEE-300bus and 118bus systems with large numbers of groups of induction motors. The studied results show that the unified algorithm yields a correct steady-state initialization without presence of reactive-power mismatch and also retains a good quadratic convergence characteristic.