Author : Sujin P. R, T. Ruban Deva Prakash, L. Padma Suresh

The necessity for flexible electric systems, changing regulatory and economic scenarios are providing impetus to the development of Distributed Generation (DG), which is predicted to play an increasing role in the electric power systems of the future. The use of distributed generation (DG) in distribution system is expected to increase in the near future due to its positive impacts such as voltage support, improved reliability, small size and losses reduction. With so much new DG being installed, it is essential that the effects on power systems be assessed accurately so that DG can be applied in a manner that avoids degradation of power quality. Distribution generators with wind power source cause voltage flicker problems which degrade the power quality. However, if controlled and regulated properly, the DG grid interfacing converters are able to improve the distribution system efficiency and power quality. This study investigates the impact of DGs on voltage flicker which is considered recently as an urgent power quality problem that can affect motor starting, temperature rise, overloading of generators, motors and may cause health risk problems due to the annoying light flicker which is consequence of voltage fluctuation. This paper also focuses on the distribution system voltage flicker control, through the DG grid interfacing converters. A novel flicker control scheme using a voltage-controlled method is developed in this paper. This control algorithm is based on instantaneous real and reactive power method which compensates current harmonics in addition to flicker mitigation. The voltage-controlled method is more flexible and has similar compensation performance compared to the conventional current-controlled method. In addition, the proposed voltage based method can be seamlessly incorporated into a voltage-controlled DG unit, which is important to provide direct voltage and frequency support in a micro-grid.

Keywords: Voltage flicker, Distributed Generators (DG), instantaneous real and reactive power method, Voltage controlled method, micro-grid.

Article published in International Journal of Current  Engineering  and Technology, Vol.2,No.2 (June 2012)