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Center for Nonlinear Studies |
Most existing electricity markets provide dispatch solutions that are based on economic grounds and, generally, do not explicitly consider security issues. As a result, during real-time operation, the system operator must check system security and implement control actions as necessary. This includes three primary tasks: security assessment, contingency filtering, and security control. In addition, market participants expect that the security control modifies as little as possible the market dispatch solution. In order to ensure that the security adjustments minimally impact the original market solution, it is necessary to model the behaviour of the system and the security constraints in detail. As a consequence, the system operator typically has to deal with a nonlinear model and advanced stability analysis concepts, such as bifurcation theory. In this work, we propose OPF-based preventive control tools to assist system operators in avoiding security problems related to voltage, small-signal, and transient instability. The starting point of our analysis is a market dispatch solution adjusted by losses. The proposed procedures are mainly of three types: security assessment, contingency filtering, and security control procedures. The characteristics of the security assessment and contingency filtering procedures depend on the instability phenomenon of interest. The security control procedures are basically redispatching procedures based on OPF problems that incorporate stability constraints. The form of these constraints depends on the instability phenomena that limit the system security. Although, for clarity, the proposed procedures for each instability problem are presented separately, they belong to a unified procedure.
Host: Marian Anghel