New Control Technique for Compensation of Neutral Current Harmonics in Three-Phase Four-Wire Systems

Use of Nonlinear loads such as power electronic converters, power supplies used in personal computers and etc is the main cause of harmonics in power distribution systems. Hence, voltage distortion on utility outlets and excessive neutral current on distribution lines have arisen and lead to a number of serious problems in distribution systems. In this paper, a series active filter is proposed to be placed in neutral of a three-phase, four-wire distribution system. This filter interacts with neutral by injecting proper current in order to suppress the excessive current harmonics, this in turn will prevent the overloading of the neutral conductor and the distribution transformer. Detailed analysis of the proposed system will be presented. Also a new control method and the related compensation characteristics of a series active filter connected in the neutral conductor are presented in this paper. This approach has been simulated using MATLAB.