Remote islanded distribution networks supplied by BESS integrated PV generation units

In some countries, electrical distribution lines have to cross areas where the installation cost could be very high and carrying out maintenance could become extremely difficult (e.g. desert areas). As a result, frequent power disconnections and blackout heavily affect the quality of supply of end-users. Oppositely, the renewable energy sources exploitation in supplying portions of the distribution network during system disconnections is very interesting, both for reducing fossil fuel use and as backup power generator. In case the islanded local electrification makes use of discontinuous and unpredictable energy sources such as photovoltaic, a Battery Energy Storage System is required to regulate the system, supplying power balance and voltage stability. In the paper, a stand-alone distribution network, corresponding in size to a typical Libyan oasis-village, has been developed and analysed. A photovoltaic generator locally supplies the islanded network, while an integrated BESS provides the daily energy balance and the system stability. The research examines the effectiveness of the proposed control strategy, developed with the scope of coordinating the role of both the solar generation and the energy storage system in facing active and reactive power requirements of the connected loads. Specific algorithms are introduced to define the optimal electrical operating condition in terms of voltage and frequency. Power system simulations demonstrate the control strategy strengths in terms of stability and time of response. Quality of supply, evaluated in terms of frequency deviations and voltage profiles, remains considerably high also considering different scenarios and introducing quick load variations. Finally, a brief investigation on integrating photovoltaic, storage and traditional generators (making use of fossil fuels) is presented.