Grid-serving charging of electric vehicles: concepts from the unIT-e² project

A wide range of use cases is being implemented and tested in the unIT-e² project, with each of the four clusters setting thematic priorities. The use cases for influencing charging processes to support grid stability are an exception: all four clusters have developed a concept for this. While these have a common goal, namely to provide the grid operator a tool for solving grid congestion, the elaborations differ in detail. The purpose of the concept paper is to first present and then compare the implementation variants from unIT-e². It thus provides approaches for concrete technical implementations, which serve as input for the discussion.

The implemented concepts differ in detail

In terms of conceptual implementation, it can be seen that the applications are implemented under different framework conditions. All clusters consider the implementation of specifications of the grid operator at a single-family house, while Cit-E-Life additionally considers the implementation in multi-party houses and Harmon-E the implementation at an industrial site. The use case is implemented in Cit-E-Life, Harmon-E, and Heav E as a curative measure. Sun-E is testing both preventive and curative implementation for the use case. While the concept of sun-E and Heav-E is to have mandatory participation, the concept in Harmon-E is to initially function on a voluntary basis. Compensation is to be provided in two clusters, as currently envisaged in the § 14a of the German EnWG (Energiewirtschaftsgesetz, Energy Act), via a uniform reduction of the grid usage charges. Heav-E, on the other hand, provides for flat-rate compensation for the provision of flexibility. Figure 1 shows the concepts with regard to the conceptual design. The concept paper also compares the technical implementations and examines the specific further developments compared with the status quo of the concepts.

Figure 1 Comparison of the concepts with regard to conceptual parameters

Addition of a market component to the mechanisms in preparation.

This concept paper shows implementation options for the grid-serving control of charging processes of electric vehicles that basically match the BNetzA’s proposal from the draft determination. The unIT-e² consortium is working intensively on the issues for a successful ramp-up of electromobility, whereby attractive business models are to be harmonized with the requirements of the electricity grids. In addition to the design of grid-serving charging, concepts for market-based flexibility procurement are also being discussed. The concepts and results are to be continuously introduced into the industry discussion.