Impact of distributed generation penetration on grid current harmonics considering non-linear loads

In this paper, the impact of large-scale penetration of distributed generation (DG) system in the presence of non-linear loads is addressed. The effect of different DG penetration levels on the grid side current harmonics is examined. It is found that current harmonics generated by downstream non-linear loads with a TDD (total demand distortion) that is compliant with IEEE Standards can lead to significantly high THD (total harmonic distortion) values at the grid side under certain loading scenarios. These low magnitude highly distorted currents may cause protection circuitry and grid-synchronizing circuitry malfunctioning, and may even cause a resonance condition with power factor correction capacitor on the network. This paper further presents a control application of Photovoltaic (PV) solar plant based DG inverter o mitigate the above harmonics problem. The increased harmonic level issue and the application of PV solar plant to mitigate such problem have been demonstrated both by MATLAB/ SIMULINK simulation studies and laboratory experimental results.