Increasing the PV hosting capacity of LV networks: OLTC-fitted transformers vs. reinforcements

The increasing adoption of domestic-scale photovoltaic (PV) systems in the UK is likely to bring significant technical voltage rise issues in low voltage (LV) networks. This work investigates the techno-economic benefits from using onload tap changers (OLTC)-fitted transformers to cope with high penetrations of PV. Two voltage regulation approaches are considered: local (busbar) and remote (furthest point). Results are contrasted with traditional network reinforcements. High resolution profiles for residential load and PV systems are used on a real UK LV network. The findings show that the OLTC-fitted transformer increases the hosting capacity of the network. The remote approach combined with adequate OLTC design performs better than the local one but the former is only needed for high penetration levels (from 70%). Finally, it is shown that the reinforcement alternative is more cost-effective for smaller penetration levels (up to 60%) in the network studied and for current prices.

I. Introduction

Nowadays there is a large consensus about the necessity of decreasing the carbon emissions in our society [1]. One alternative to face that challenge is to increase the use of domestic-scale low carbon technologies (e.g., photovoltaic systems, electric heat pumps, electric vehicles, micro combine heat and power, etc.). However, the adoption of these technologies might lead to some problems in low voltage (LV) distribution networks. For example, photovoltaic (PV) systems can produce voltage rise, increase energy losses, produce higher harmonic content, etc. [2].