Computational framework for assessing voltage security using energy methods

The restructuring of the electric power industry has intensified the need for efficient and accurate tools that identify threats to reliability, gauge their severity, and prescribe their cures. Today's diverse catalog of large, simultaneous, geographically expansive energy transactions poses severe challenges to the thermal capacities of transmission ties and the angular and voltage stability limits of the areas they connect. Incidents of the summer of 1999 suggest that threats to voltage stability are perhaps the most difficult to address, largely because of a lack of efficient and accurate tools for describing and identifying voltage-related problems.; This thesis develops a theoretically sound and computationally practical set of tools for assessing and quantifying the voltage security of a power system in terms of an intuitive measure. This measure, called the maximum loading percentage (MLP), expresses the proximity of a system to serving the maximum amount of load it can furnish without experiencing a voltage collapse. When used in conjunction with the adaptive system reduction technique introduced in this research, an effective method of screening the system for areas of concern, and a new, improved method for locating alternative power flow solutions, the proposed measure quickly and accurately evaluates the voltage security of power systems, even those of large dimension. This work also introduces a technique for identifying the most effective controls for mitigating the effects of voltage collapse once it occurs. Finally, it advances power flow calculation methods by offering algorithms that improve the convergence properties of power flow engines in solving modern power system models. The proposed tools are applied to systems ranging in size from two to several thousand buses.