Increase the hosting capacity of four-wire low-voltage supply network for embedded solar generators by optimising generator and load placement on the three supply phases

Abstract

Australia has topped the world in the penetration of residential rooftop solar generation systems. These residential solar generation systems are connected to the low-voltage (LV) supply network, which is not designed for two-way flow of electricity. Localised voltage rises due to excess solar generation feeding energy back into the supply network is commonly experienced. Supply utilities do not generally select the phases for the connection of solar generators. When load/generation is not balanced between the three LV supply phases, phase voltage unbalance arises as a result, which aggravates the phase voltage condition due to neutral voltage shift. Balancing loads and solar generation on each phase is quite complex due to the stochastic nature of loads and solar generation. This study proposes an allocation methodology based on minimising voltage unbalance on the supply nodes, subject to the constraint that voltages on each supply node/bus are within the regulatory limits. The effectiveness of the approach is illustrated by computer modelling studies implemented in MATLAB© and Open Distribution System SimulatorTM, using load and network data of a real-LV network in Australia.