Impact of on-Load Tap Changers and Smart Controllers on the Distributed Renewable Energy Hosting Capacity

Abstract

In the course of the global energy transition, the power infrastructure is subject to fundamental change taking place at unprecedented speed. Existing electrical networks are increasingly exposed to operation near their technical and thermal limits due to the impact of grid-integrated renewable energy sources as well as by variable loads such as electric vehicles. Most current networks were not designed to operate under today’s conditions. Distribution network operators are taking measures to keep their networks complaint to grid codes while considering the pressure to integrate variable distribution generation and consumption units to meet the climate goals. It is a challenging task to operate distribution networks with high volatility in the generation and consumption.  New technologies, such as smart transformers, battery storage systems, and advanced load and generation controllers, have emerged to help mitigate the effects of distributed renewables and variable loads, but established technologies, such as on-load tap changers, can also provide very effective solutions for increasing the hosting capacity of variable renewable energy resources, as demonstrated in this paper. Simulation results show that on-load switches combined with smart controllers can improve the hosting capacity by a factor of 1.92 in distribution feeders where overvoltage is the main constraint to the integration of distributed renewable energy sources.