The Voltage Security Assessment (VSA) project is designed to be part of the suite of advanced computational tools for congestion management that is slated for practical applications in California in the next few years. Modern voltage assessment methods include the development of such advanced functions as identification of weak elements, automatic selection of remedial actions and automatic development of composite operating nomograms and security regions. Real-time production-grade VSA tools are becoming increasingly available nowadays. These tools are integrated with EMS/SCADA systems and use results from the state estimator.

Some advanced contemporary real-time applications already promote the idea of using the security regions determined in parameter space with the composite boundaries limited by stability, thermal, and voltage constraints. At the same time, the majority of the tools are still based on the static system power flow models and implement such traditional approaches as sink-source system stressing approach, P-V and V-Q analyses, V-Q sensitivity and modal analysis. Unfortunately, many of the most promising methods suggested in the literature have not been implemented yet in the industrial environment, including the state-of-the-art direct method to finding the exact point of collapse. Currently there exists no real-time monitoring tool for voltage security assessment. The problems of voltage security will be exacerbated by the effects of multitransfers through the network. These sets of simultaneous transfers are manifest because of the buying and selling of electric power across the boundaries of control areas. Moreover the point of production and the point of delivery may be in geographically distant locations.