Tools for voltage collapse assessment

A variety of tools and techniques used for voltage stability analysis in power systems are discussed in this paper, with particular emphasis on their application to electricity markets. Thus, the computation of transfer capability limits, which are directly associated with the security constraints used in energy auction systems, by means of continuation power flows (CPF) as well as maximum loadability optimal power flows (OPF) are discussed in some detail. The paper also describes a "standard" security-constrained (SC) OPF auction, as well as two recently proposed voltage-stability-constrained (VSC) OPF-based techniques used to better represent security limits in market clearing and power dispatch techniques. A simple 6 bus example is utilized to illustrate the application of all these methodologies, and discuss and compare the various market prices, power and system security levels obtained from the different techniques, showing the advantages of the VSC-OPF techniques over the standard SC-OPF