Combined detailed and quasi steady-state time simulations for large-disturbance analysis

This paper deals with the simulation of long-term responses of power systems to large disturbances in the presence of discrete events. After outlining the power system model under the quasi steady-state (QSS) approximation, a method combining detailed and QSS time simulations is presented, the former being used for accuracy and the latter for efficiency reasons. Detailed time simulation is used to analyze the short-term period following a large disturbance and identify the discrete controls triggered. Next, QSS simulation is used to simulate the same time interval with the discrete controls imposed as external events, before letting the system evolve as usual in the long-term. This simple method has been successfully tested on the Hydro-Québec system.