Using Automatic Low-Voltage Regulators to Increase Distribution Networks' Hosting Capacity: A Real case Study in Milan, Italy

The energy transition is leading to growing electrification of consumption and production from non-programmable renewable sources within distribution networks. In this scenario, new challenges emerge in the operation of distribution networks, which distribution system operators must efficiently manage. The paper investigates a real case study in Milan's distribution network where frequent overvoltage and under-voltage problems have led to the deployment of an automatic low-voltage regulator to guarantee a reliable service of a long rural low-voltage feeder with photovoltaic and storage systems connected to it. Firstly, the paper presents current voltage issues in distribution networks, the working principle of the installed low-voltage regulator and a brief description of the feeder under study. Secondly, after the description of the optimal sizing and location through the feeder, the field data collected by the low-voltage regulator over a couple of months is punctually and statistically analyzed to demonstrate the valuable impact on voltage stability. In the end, the paper highlights the benefits gained by Unareti, Milan's distribution system operator, comparing the presented innovative voltage control solution with the traditional approach of network reinforcement from both technical and economic points of view.