MEASURES OF VOLTAGE INSTABILITY AND VOLTAGE COLLAPSE .1. THEORETICAL DEVELOPMENT

The purpose of this paper is to present a theoretical foundation for m odeling, analysis, and testing of systems experiencing voltage collaps e. The boundary theorem of the load how feasibility region (FR), the s teady-state stability margin and the sensitivity of the stability marg in to bus voltages and bus injections are defined. The theoretical con cept of feasibility region and practical multiple load how solutions a re unified and presented in this paper. The voltage-weak points and ke y contributing factors affecting the system voltage instability can be identified according to the values of the sensitivity of the stabilit y margin to bus voltages and bus injections.