Computer simulation study of voltage stability of a power system

This paper presents the methods and results of a simulation study of voltage stability of a power system. Important load and reactive power components are included. A nine-machine electric power system is chosen as the working example so that the dynamic interactions among machines in a system are adequately represented. Since it is a very high-order system with many nonlinearities and variable constraints and including both fast transients and slow dynamics, a variable step size is chosen for the integration and a new method is developed to solve the Jacobian matrix equations in each integration step without taking the inverse of a very large matrix directly. Case study results show that all voltage-dependent load and reactive power components are important and must be adequately modeled in voltage stability studies