Volt-VAr Optimization of a Low Voltage Distribution Network in Nigeria

Volt-VAr optimization (VVO) is important in a distribution system as the performance of the entire network depends on the voltage profile to a very large extent. The deployment of renewable energy sources, particularly photovoltaic (PV) systems, is usually achieved at the medium voltage (MV) and low voltage (LV) levels of distribution feeders and may exacerbate the challenges associated with maintaining the voltage profile within the pre-defined limits. For such a PV-rich system, VVO can be carried out such that the inverter-based PV systems can actively participate in voltage regulation and optimization by providing flexible reactive power support. This paper addresses the voltage concerns associated with high PV penetration by implementing a distribution grid optimal power flow (DOPF) problem on a realistic LV distribution network in Kano, Nigeria. The current injection-based I-V DOPF formulation is used to model the grid and the VVO utilizes the reactive power of the PV inverter to minimize the active power losses in the network. The results demonstrate the ability of the VVO to perform voltage regulation and can serve as a viable technique for mitigating voltage violation issues in the Nigerian grid.