Gaining experience with a regulated distribution transformer in a smart grid environment

The regulated distribution transformer can be a powerful tool against voltage range problems in low voltage grids with a high amount of distributed power generation. To gain experience with this new technology the German DSO EnBW Regional AG has equipped one of its MV/LV-substations with a regulated 400-kVA-transformer developed by Siemens AG. This paper outlines the general benefits of using regulated distribution transformers and EnBW´s steps to implement and test the aforementioned prototype. The technology of this transformer with its on-load voltage regulation is described in detail as well as the process of finding and optimizing a suitable voltage control algorithm. After several months of successful operation it can be stated, that the regulated distribution transformer has proved its potential for a permanent use the realization of a new “smarter” distribution grid.