Integrating micro-generation into distribution systems — a review of recent research

Micro-generation in its various forms, photovoltaics, micro-wind and micro-CHP to name the primary technologies, is steadily gaining market share and is growing in popularity with energy policy makers. Most installations are connected to existing rather than purpose designed distribution systems, and this is likely to continue for some time. Given that existing networks were not designed with such distributed generation in mind, a series of related problems can be caused by these new sources of generation, in particular local voltage rise and the potential to exceed thermal limits of the certain lines and transformers. Distribution network operators (DNOs) have legitimate concerns regarding these issues and also the efficacy of the existing protection arrangements. There are of course also potential benefits. Enthusiasts for micro- generation point to a reduction in CO₂ emissions, a reduction in distribution losses and increased security of supply amongst others. Research has been underway in recent years to quantify both the problems and the benefits associated with micro-generation, and to determine limits to their penetration into existing networks. Moreover, new approaches to system design and operation are immerging. Research developments and progress with the installation of micro generation in the UK will be used to highlight the key issues. The perceived technical, commercial and regulatory barriers to uptake of micro generation are also discussed alongside current connection codes and requirements.