A novel approach for contingency ranking through voltage stability indices to assess the security in a power network

摘要

Investigation and online monitoring of power system stability have become vital factors to electric utility suppliers. At present, power system utilities operate very close to the limit of system stability owing to an increasing number of new economic and environmental restrictions. The most important task in security analysis is the problem of identifying the critical contingencies from a large list of credible contingencies. The condition of voltage stability in a power system can be characterized by the use of voltage stability indices. This paper presents the Fuzzy approach for ranking the contingencies using a composite-index based on a parallel operated Fuzzy Inference Engine. The system user is provided with the capability to determine the set of conditions under which a line-outage is critical, and if critical, then how severe it is, thereby providing some degree of severity of a particular contingency through a Fuzzy solution. In this paper, two powerful stability indices called voltage stability index (L-index) and fast voltage stability index (FVSI) are considered along with bus voltage magnitudes as post contingent quantities to rank the contingencies. The proposed method is tested on an IEEE-14 bus system.