Next Generation On-Line Dynamic Security Assessments

(PSERC) is a multi-university Center conducting research on challenges facing the 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 for internal use if appropriate attribution is given to this document as the source material. This report is available for downloading from the PSERC website. Executive Summary This project addresses five elemental aspects of analysis for the enhanced performance of on-line dynamic security assessment. These five elemental components include: a) A systematic process to determine the right-sized dynamic equivalent for the phenomenon to be analyzed, b) Employing risk based analysis to select multi-element contingencies, c) Increased processing efficiency in decision-tree training, d) Using efficient trajectory sensitivity method to evaluate ability for changing system conditions, and e) Efficient determination of the appropriate level of preventive and/or corrective control action to steer the system away from the boundary of insecurity. An overview of the work accomplished in each part is presented below: To account for the challenges associated with rapid expansion of modern electric power grid, power system dynamic equivalents have been widely applied for the purpose of reducing the computational effort of dynamic security assessment. Dynamic equivalents are commonly developed using a coherency based dynamic equivalencing approach in which a study area and external area are first demarcated. Then the coherency patterns of the generators in the external areas are determined. A commonly used method is to introduce faults on the boundary of the study area and to group the generator with similar dynamic responses in the external area. Other methods, such as slow coherency-based method and weak-link method have also been proposed. As a result, the coherent generators in the external area are equivalenced. Network reduction is then performed at the interface between the study area and the external area to suitably interconnect the equivalent generators. In the process of building a dynamic equivalent, the definition of the retained area can significantly impact the effectiveness of the final reduced system. As more components are included in the retained area, more attributes related to the dynamic characteristics of the study area can be retained. In conventional dynamic equivalencing applications, the study area and external area are arbitrarily determined without examining the phenomenon of interest with respect to the system …