Voltage stability margin estimation for a load area using a three-bus equivalent

This paper describes a new method for estimating the power transfer limits on tie lines of a load area represented using a three-bus equivalent recently proposed. This new method uses companion matrix eigenvalues to solve a sextic equation about the maximum active power transfer against voltage instability and is able to handle more general load increase scenarios. The proposed method is compared with a previously proposed partial derivative calculation based method using an artificial three-bus system to demonstrate its better accuracy and is also tested on the Northeast Power Coordinating Council 140-bus power system for calculating the power transfer limits of three tie lines of the Connecticut Load Center.