Placement and operation strategy of FACTS devices using optimal continuous power flow

In this paper, an effective method is presented to determine the security margin against voltagecollapse, and improve it by means of facts devices in the optimal continuous power flow framework.the primary methods for determining the system's critical states of voltage collapse points are basedon the convergence of the newton-raphson method in various iterations. unlike these methods, inthis investigation, a method based on sequential quadratic programming is proposed to overcome thedivergence of the problem near the critical states, and also to incorporate operation and control constraintsthrough optimal continuous power flow. furthermore, two facts devices, the thyristor-controlled seriescapacitor (tcsc) and the static var compensator (svc), are mathematically represented and employedin the optimization process to improve the security margin. the proposed method is implemented on apractical power network to investigate the efficacy of the method