Power quality analysis of a three phase ac-to-dc controlled converter

The controlled ac-to-dc converters are used to control the output dc voltage. A six pulses controlled ac-to-dc converter is one of the efficient converters that is widely used in many industrial applications. The main advantage of any higher pulse converter in ac-to-dc conversion is low ripple factor but on the other hand, it highly distorts the input supplied currents. This distortion degrades the power factor, and increases the stresses across the protective devices and measuring units in the power system, hence exhibits poor power quality. It becomes important to analyze the power quality in ac-to-dc power conversion. A new approach called pulse selective method is introduced to analytically calculate the harmonics in a three phase rectifier circuit both for input and output. Then power quality performance parameters are analyzed on the basis of computed harmonics. Simulation modeling is used to verify the proposed method.