Performance Analysis of Distribution Networks under high Penetration of Photovoltaics in Mauritius

Traditionally, for a radial low-voltage (LV) distribution network serving residential loads, it was simpler for the electric utility to predict the demand and adjust the generation from power plants accordingly, thus offering a high reliability of supply. However, with the increasing penetration of photovoltaics (PV) on rooftops of residential houses, it has become difficult to ensure the same reliability without the performance of the distribution network being affected. At times of low loads in residential houses, PV systems will inject power upstream of the host LV network and affect the behavior of the distribution network. In this paper, an LV distribution feeder in Mauritius has been modelled on DigSILENT Power Factory software to simulate how the network performance is affected under high PV penetration. Novel indices were developed for analyzing grid behavior in terms of maximum voltage variation from nominal value, average feeder loading, feeder losses, and transformer reserve. These performance indices were evaluated against three different voltage control strategies of PV inverters in order to choose the best one which will optimize the performance of the network. Furthermore, variations in the loads and PV generation over a 24-hour period were also considered in the performance analysis of the grid.