84 Pulse Converter, Design and Simulations with Matlab

Abstract

Flexible Alternating Current Transmission System (FACTS) devices have been proposed for fast dynamic control of voltage, impedance, and phase angle in high-voltage AC lines. The application of this technology has opened new and better opportunities for an appropriate transmission and distribution control. The efforts performed all over the world to improve the power quality have originated several power conditioners, which by themselves contribute to power degradation due to switching of the semiconductor devices, and harmonic effects generated in the converters. Thus, big elements have been used as filters, pursuing to have appropriate power quality with low extra noise. Because of that, this technology has not been probed in stringent applications such as hospitals or airports, which are two of the environments to consider. The series and shunt power systems compensation are used with the purpose of improving the operating conditions; respect to the voltage, the compensation has the purpose of handling reactive power to maintain bus voltages close to their nominal values, reduce line currents, and reduce system losses. The voltage magnitude in some buses may be controlled through sophisticated and versatile devices such as the StatCom, which is the smaller and most cost effective FACTS device in many applications (Hingorani, 2007), and is a power reactive source (Acha et al., 2004; Song & Johns, 1999). By regulation of the StatCom’s output voltage magnitude, the reactive power exchanged between the StatCom and the transmission system can be controlled (CIGRE, 1998; Davalos, 2003; El-Moursi & Sharaf, 2005; Hingorani & Gyugyi, 2000;Wang, 2000). This Chapter describes how the assembling of a Voltage Source Converter (VSC) that meets the IEEE Std. 519-1992 (IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems) is performed, and emphasizes its development through Matlab simulations. The low Total Harmonic Distortion (THD) that this VSC produces allows this power conditioner to be considered for its use on stringent applications or in the reactive power compensation and the power quality improvement. The reinjection principle used, makes this proposal to be considered as an affordable solution to the sinusoidal synthesization due to the reduced number of switches needed. The reinjection transformer is one of the most important elements in this configuration, and it can have a wide turn ratio’s variation without leading out the special application standards.