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Local Reactive Power Control Methods for Overvoltage Prevention of Distributed Solar Inverters in Low-Voltage Grids
Location: USA
Publication date: 2011-12-07
Published in: IEEE Journal Photovoltaics, December 2011
ref. DOI: 10.1109/JVPHOTOV.2011.2174821
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Demirok, E. , Casado González,P. , Frederiksen, K.H.B. , Sera, D. , Teodorescu, R.

 

Abstract

The main objective of this study is to increase the penetration level of photovoltaic (PV) powerproduction in low-voltage (LV) grids by means of solar inverters with reactive power controlcapability. This paper underlines weak points of standard reactive power strategies which are already imposed by certain grid codes, and then, the study introduces a new reactive powercontrol method that is based on sensitivity analysis. The sensitivity analysis shows that the same amount of reactive power becomes more effective for grid voltage support if the solarinverter is located at the end of a feeder. Based on this fundamental knowledge, a location-dependent power factor set value can be assigned to each inverter, and the grid voltagesupport can be achieved with less total reactive power consumption. In order to prevent unnecessary reactive power absorption from the grid during admissible voltage range or to increase reactive power contribution from the inverters that are closest to the transformer duringgrid overvoltage condition, the proposed method combines two droop functions that are inherited from the standard cos φ(P) and Q(U) strategies. Its performance comparison in terms ofgrid losses and voltage variation with different reactive power strategies is provided by modeling and simulating a real suburban LV network.