Smart Inverters in LV networks: A Review of International Codes and Standards, and Opportunities for South Africa

Over the past few decades, the percentage of grid-interconnected distributed energy resources (DERs) has increased significantly. Even higher percentages are expected in the future as more countries implement policies, energy resource plans, and incentives towards the adoption of renewable energy. However, it is not so simple to progress towards a larger penetration of DERs, as there are associated technical challenges that threaten the existing distribution network's stability, reliability, and power quality. Smart inverters can be used to address grid integration issues related to voltage or frequency, disconnection from the grid, and overgeneration, through dynamic and central operation and control of these inverters. Due to the grid support provided by smart inverters, various countries have redefined grid codes motivated by the need to optimize distributed generation (DG) utilization while ensuring system adequacy. This paper explores existing grid codes and related regulations within the context of advanced inverter functionality, in leading states and countries with high DG penetration, particularly Germany, California, and Hawaii. The content of the international regulations are contrasted with those in South Africa to identify areas where changes are needed. The results show that South Africa would benefit from having a communication protocol, similar to IEEE 2030.5, as well as defined voltage and frequency regulation functions, similar to those stated in California Rule21 and Hawaii Rulel4H. Standards modification to include smart inverter requirements that are applicable for all DER sizes and types, including solar, wind, energy storage, and smart loads, would also be beneficial.