Transient stability assessment and preventive control of power systems

As the electric utility industry moves toward a more open and competitive environment, the power system will be stressed significantly. Maintaining the stability of the power system is an important concern. On-line transient stability assessment and preventive control tools can be used to enhance the security of a power system. In the first part of this thesis, the SIngle Machine Equivalent (SIME) method for on-line transient stability assessment is presented. SIME is a recently proposed hybrid direct-time-domain method that is better suited to the tasks of contingency filtering and ranking than the conventional time-domain methods. The SIME method for transient stability assessment is implemented in Matlab and tested using different power system models. Case studies indicate that this method is reliable in identifying and ranking harmful contingencies with respect to transient stability problems.; In the second part of this thesis, SIME is used in a transient stability preventive control strategy. The SIME method for transient stability preventive control is implemented in Matlab and is tested on different power system models. This method is successful in stabilizing the harmful contingencies identified in the SIME transient stability assessment. Programs for the stabilization of individual contingencies and the simultaneous stabilization of multiple contingencies are developed. By scheduling the real power outputs of generators suitably, it is possible to enhance the security of a power system with respect to transient stability problems.; In the final part of this thesis, a method to integrate both dynamic and steady-state security constraints in the conventional optimal power flow is proposed and implemented. Through case studies, it is shown that it is possible to achieve the lowest possible total fuel cost while satisfying specific constraints with respect to stability and post-fault operating conditions.