Performance Analysis of Non-Linear Load Effects on a Micro-Grid Supplied by Photovoltaic Power Plants

Sanna C;Gawronska M;MUSIO, MAURA;DAMIANO, ALFONSO

2014-01-01

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Abstract

In this paper the power quality analysis of a micro-grid characterised by a relevant presence of non-linear electric loads and non-linear electrical generators, like photovoltaic (PV) systems, is presented. The presence of nonlinear loads, such as PCs, printers, electronic equipment and other such devices, determines a time varying evolution of micro-grid active and reactive powers and causes currents imbalance in the three-phase system. Moreover, non-linear loads introduce current distortions that pollute the electrical network with harmonic components. In this framework it is interesting to analyze how the introduction of PV plants can influence the power quality (PQ). In fact, the harmonic pollution associated with the presence of non-linear loads can interfere with PV energy conversion systems, determining high voltage distortion and worsening the micro-grid stability and reliability. However, under particular energy balance conditions the introduction of PV plants could improve the power quality reducing the harmonic components. In the present paper, the impact of two different PV systems on the power quality of the tested micro-grid has been analyzed for different load conditions. Total harmonic distortion (THD) indexes have been correlated with the active power profile and their evolutions have been discussed referring to the active power absorbed and generated.