Integrated Security Analysis

This is a project report from the Power Systems Engineering Research Center (PSERC). PSERC is a multi-university Center conducting research on challenges facing a restructuring electric power industry and educating the next generation of power engineers. More information about PSERC can be found at the Center's website: Notice Concerning Copyright Material PSERC members are given permission to copy without fee all or part of this publication if appropriate attribution is given to this document as the source material. This report is available for downloading from the PSERC website. In today's power marketplace, the ability to accurately and quickly determine system security limits has become increasingly important. Over the past several decades, research has resulted in significant advances in analytical techniques needed for quantifying system security limits. At the same time, the phenomenal growth in computational speeds of modern computers has brought on-line security analysis closer to practical use. Despite these great strides, system operators continue making limited use of new system analysis tools. Operators tend to follow relatively fixed sets of procedures and pre-calculated system limits. One of the factors hindering operator adoption of new sophisticated security techniques is their limited understanding of the underlying analysis methods on which the new tools are based. Another barrier to adoption is the natural preference to use older, well-understood and tested tools given the critical responsibilities operators have for maintaining security. There is a need for a comprehensive security analysis framework that operators can use. This project explored the issues associated with developing such a framework and implemented an approach that integrates techniques that make extensive use of off-line studies. In doing so, the project has contributed to the understanding of integrated security analysis in a number of ways. • A comprehensive framework was developed for on-line estimation of security margins, calculated based on current operating practices. • The framework includes families of estimators, each specialized for specific system limits and the appropriate security criteria (i.e., static, dynamic or voltage). The estimators can be combined to provide an overall assessment of system operating conditions. • A system of estimators was implemented and tested on a modified New England 39 bus system. • Based on the insights from the New England system, a more sophisticated set of estimators were implemented and tested on a 6500 bus model of the Western Area system. The focus of this study was the California-Oregon intertie transfer limits. • …