Harmonic Compensation in Grid Interconnected DG Units by Closed Loop Control

Abstract

This paper deals with improvement of power quality problem namely harmonic problem using distributed generation as their source of electricity. The harmonics occur in such a system because of the nature of loads connected. There are many power quality problems; out of which harmonics normally caused by nonlinear loads like variable frequency drives, fluorescent lightning, office computers etc. have adverse effects on the power quality. Also, harmonic detection and prediction is of utmost importance because it can cause electrical noise, sensitive equipment malfunctioning, tripping of circuit breakers etc. Reduction of harmonics is considered very important for the proper functioning of the customer equipment. There may be many harmonic mitigation techniques including active and passive methods, and choosing the best method out of it may be a challenging task. Proposed method is for single phase inverter for DG systems that requires power quality features like harmonic and its compensation for grid connected operation. Here simulation results in DG and grid connected mode is shown. An active harmonic compensation technique by using current controlled technique has been discussed in this paper, which is basically a closed loop control technique which will eliminate the DG current tracking errors. The effectiveness of the harmonic compensation scheme developed has been verified by the simulation and hardware developed for 1-phase system. The harmonics caused by the nonlinear loads has been compensated by using closed loop control, in which the harmonic current frequency variation is taken as closed loop or given as a feedback to the microcontroller, which in turns gives the pulses to the driver circuit and the driver circuit gives the switching pulses to the gate of the MOSFETS, which is known as PWM technique and this is how harmonics are eliminated in the system. The simulation has been carried out in Matlab 2013. The simulation deals with the PQ theory based PI controller which minimizes the harmonics generated by nonlinear loads. The simulation and hardware results obtained validate this technique.

Keywords: Distributed generation, harmonics, MATLAB/simulink

Cite this Article

Asha Gaikwad, Prachi Jeevane. Harmonic Compensation in Grid Interconnected DG Units by Closed Loop Control. Journal of Power Electronics and Power Systems. 2017;

7(1): 9–17p.