STATIC VOLTAGE STABILITY ANALYSIS USING FUZZY SET THEORY

Abstract

One important threat of heavily loaded line is voltage instability. A prior knowledge of the voltage stability limit at various operating conditions is essential to operate the system with an adequate safety margin. With the increase in power demand and limited power sources has caused the system to operate at its maximum capacity. A study that is able to determine the maximum capacity limit before the voltage collapse must be carried out so that necessary precaution can be taken to avoid system capacity violation. If power flow equations are not solvable under some specified conditions, one can conclude that generation and network are not physically capable of supplying the specified load. Therefore, modifications are needed on the generation dispatch and on the transmission system in order to securely supply that load requirement. It is necessary to know that how far the current system operating point is.from the voltage stability limit. In this paper voltage stability index is calculated in fuzzy environment. The uncertainties are properly modeled in terms of fuzzy sets by assigning membership functions. The fuzzy stability index is compared with the voltage stability index calculated in non-fuzzy environment. This index will indicate which line is going to cross