Active and Reactive Power Flow Control using FACTS Devices

Abstract

ABSTRACT Flexible alternating current transmission systems (FACTS) technology opens up new opportunities for controlling power and enhancing the usable capacity of present, as well as new and upgraded lines. The Unified Power Flow Controller (UPFC) is a second generation FACTS device which enables independent control of active and reactive power besides improving reliability and quality of the supply. This paper describes the real and reactive power flow control through a transmission line by placing the UPFC at the sending end of an electrical power transmission system. The power flow control performance of the UPFC is compared with that of the other FACTS device called Static Synchronous Series Compensator (SSSC). Simulations are carried out in Matlab/Simulink environment to validate the performance of the UPFC. Keywords FACTS, Matlab/Simulink, Real and reactive power, SSSC, UPFC. 1. INTRODUCTION In today’s highly complex and interconnected power systems, there is a great need to improve electric power utilization while still maintaining reliability and security. While power flows in some of the transmission lines are well below their normal limits, other lines are overloaded, which has an overall effect on deteriorating voltage profiles and decreasing system stability and security. Because of all that, it becomes more important to control the power flow along the transmission lines to meet the needs of power transfer. On the other hand, the fast development of solid-state technology has introduced a series of power electronic devices that made FACTS a promising pattern of future power systems. Power flow between two buses of a lossless transmission line is given by :