جایگذاری و استراتژی بهره برداری از دستگاه های FACTS با استفاده از جریان بهینه توان پیوسته

In this paper, an effective method is presented to determine the security margin against voltage collapse, 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 based on the convergence of the Newton-Raphson method in various iterations. Unlike these methods, in this investigation, a method based on sequential quadratic programming is proposed to overcome the divergence of the problem near the critical states, and also to incorporate operation and control constraints through optimal continuous power flow. Furthermore, two FACTS devices, the Thyristor-Controlled Series Capacitor (TCSC) and the Static VAR Compensator (SVC), are mathematically represented and employed in the optimization process to improve the security margin. The proposed method is implemented on a practical power network to investigate the efficacy of the method.

The capacity of power systems can be increased by their performance improvement via optimal use of existing power equipment, rather than by installing new transmission lines. Load growth and the non-optimal use of electric power transmission lines adversely affect the stability of power systems. Although power system control and stability have been studied for several decades, they attract special attention, due to ever-increasing electricity demand and economical considerations. The high cost of transmission line expansion, including equipment, installation and right of way, force transmission lines to operate at their maximum capacity. Therefore, voltage stability, even under normal conditions, becomes more and more difficult to guarantee

In this paper, a method for determining the voltage security margin in a real power system is presented. The mentioned approach considers the problem as an optimization problem that should maximize the load demand (MVA). This optimization problem is solved by means of the SQP technique and the system’s critical states values regarding voltage collapse, and, hence, the differences between the current values and these values will be obtained as the present security margin of the system. Unlike previous methods for determining the security margin, which made use of load flow iteration, caused the Jacobean matrix to experience singularity, and the equations of load flow to diverge on the verge of a critical state (voltage collapse verge), the presented method in this study is able to determine the correct answers. Furthermore, to improve the security margin, TCSC and SVC modeling and their appropriate equations are used to be added to optimization relations. The results obtained from implementing the proposed method on FPG show that the security margin can be improved about 40% by using FACTS devices. Besides, in this study, it is observed that by using FACTS devices, bus voltage violation and loss can be reduced simultaneously.