Multi-Criteria Analysis of Grid Expansion Concepts on the Low Voltage Level

In recent years, the power generation and consumption in Germany have undergone fundamental changes. New political regulations and the renewable energy law have resulted in a sharp increase in the installed generation capacities of photovoltaics connected to a low voltage grid. Distribution system operators are faced with the challenge of preventing grid component overload as well as a violation of voltage range. Due to increasing requirements of grid expansion in future years, distribution system operators must evaluate new expansion concepts compared to conventional ones. One interesting approach is the installation of Voltage Regulated Distribution Transformers (VRDT) regulating the voltage level of distribution grids. In this paper, the local network of one of the largest German distribution system operators is analysed in the context of future requirements for grid expansion using the conventional and VRDT expansion. Grid structures have grown over the last decades and therefore vary widely in their grid topologies. A classification of the entire grid in a few classes results in high inaccuracies. Therefore, the creation of synthetic grid structures is developed for the calculation of the required network extension. In addition, both grid expansion concepts are evaluated not only for financial aspects, but against environmental, economic, technological, and social dimensions using a multi-criteria decision making approach. The study shows a high market potential for VRDTs in low voltage grids with an increasing enforcement level of photovoltaics.