On-line dynamic security assessment in energy management system

In this paper an on-line dynamic contingency screening and ranking approach integrated with fast potential energy boundary surface (PEBS) method and corrected hybrid method to enhance efficiency of system transient stability assessment for a large complex power system is proposed. Three levels of assessment are included in the approach. The first is the prescreening level. Two contingency lists, must run list and mild contingency list, are determined based on experience with power system operation and off-line studies. Ignoring all mild contingencies, the must run contingencies that may threaten dynamic security of the system is further screened by the second PEBS screening level. The PEBS approach re-ranks the must run contingencies according to their critical clearing time evaluated at this level. Neglecting highly stable contingencies, the marginal stable and unstable contingencies are further analyzed in the corrected hybrid method to detect their stability behaviour and operation limits. Case studies are presented to demonstrate the applicability of the method to real size power systems