Impact of neutral conductor sizing on LV networks hosting capacity - a Monte-Carlo analysis

Due to the rapid increase in residential PV capacity, it gets more and more difficult for an LV grid to absorb power at peak hours due to overvoltage issues, causing concerns to DSOs and prosumers who are temporarily unable to inject power into the grid. Monte-Carlo simulations were performed with a parametrized LV feeder model representing typical feeder characteristics in Belgium, in order to notably gain insights on the impact of the feeder cable type on the risk of overvoltage occurrences. The simulations’ outputs highlighted the significant impact of the cable type, with a noteworthy influence of the neutral conductor impedance. The significance of impact of the neutral impedance is directly linked to the significance of the unbalance levels of PV production. The gain in terms of voltage excursion (|Vph-N- Vnom|) reduction can be large for a DSO switching from asymmetrical cables (with reduced neutral cross-section) to symmetrical ones. Voltage excursion reductions of 22 to 32% are typically observed, although much larger reductions have been obtained. The reduction of the risk for overvoltage occurrences ranged from 43 to 74% depending on the asymmetrical/symmetrical cable pairs considered.