Challenges of Future Distribution Systems with a Large Share of Variable Renewable Energy Sources – Review

Power distribution systems with a high share of Variable Renewable Energy Sources (VRE) face problems due to the variability, uncertainty, and non-dispatchable nature of VRE. This paper reviews and discusses the pertinent challenges arising for steady state operation of future distribution systems with a large share of weather-dependent renewable energy sources. The substantially increased amount of VRE in future distribution networks transforms them into highly weatherdependent networks with limited real-time observability. Challenges of such networks, like sustained over-voltage, increased power losses in the network, growing stress upon the existing network assets and changing interactions with the upstream grid, are addressed in the paper. Illustrations from past research and practical demonstrations of these challenges are presented to emphasize the severity of the problems.