Experimental validation of a low-voltage regulator model — a case study of a Maltese low-voltage feeder

Abstract

Solar photovoltaics in Malta have increased substantially over the years, both at large scale and residential scale. The present installed capacity is already having a negative impact on Malta’s’ grid infrastructure, causing problems due to the reverse power flows (resulting from oversupply) and related issues such as voltage rise. This paper considers the integration of a low voltage regulator in a low voltage feeder in a semi-rural area in Malta. A thyristor-controlled transformer-based low voltage regulator was modelled and simulated in MATLAB/Simulink using the PLECS blockset. Experimental results were also obtained via measurements of the voltage profiles at 70% of the actual low voltage feeder that showed several instances of over and under voltage events. The outputs obtained from the simulation model strongly agreed with those obtained from the field testing thereby validating the simulation models that were developed in this study. Results show that the voltage on the feeder was successfully regulated to around the nominal voltage of 240 V. The regulator failed to correct the voltage to within ±10% in one occurrence where the load demand and hence the voltage drop was too high.