Designing future residential LV networks with EVs and PVs: a bi-period OPF-based approach

• Proposes a bi-period AC OPF for planning brand-new LV networks with 100% EV and PV. • Minimizes transformer and conductor/cable cost for different tap changer technologies. • Considers locational effects of where the LV network is connected to an MV feeder. • LV OLTC with thin cables: best design for large LV networks at the end of MV feeders. • Off-LTC with thick cables: best design for LV networks near the start of MV feeders. The proliferation of electric vehicles (EVs) and residential photovoltaic (PV) systems in three-phase low voltage (LV) networks is prompting the need for cost-effective designs in brand-new neighborhoods that address the challenges of managing voltage (drop/rise) and asset congestion. This requires selecting the most appropriate conductors, transformers, and voltage regulation devices, which becomes a complex combinatorial problem. This paper proposes a bi-period three-phase AC Optimal Power Flow methodology to minimize asset costs while capturing the time-dependent impacts of EVs, PVs, and the locational effects on the transformer’s primary voltage. The proposed approach is demonstrated using two realistic residential Australian LV networks: one having a single circuit with 31 houses, and another having multiple circuits with 89 houses. The approach identified optimal designs for both networks that minimize costs addressing the technical challenges. For single-circuit networks, off-load tap changers with thicker conductors is the most cost-effective design for both close and distant locations (relative to the primary substation). However, in multi-circuit networks, particularly in distant locations with significant voltage variations, on-load tap changers with thinner conductors is the most cost-effective design. These findings highlight the importance of considering individual network characteristics to optimally design brand-new LV networks with EVs and PVs.