BDL Next – Empowering Mass Bidirectional Charging

The transition to electric vehicles in the mobility sector is an integral element of the energy transition and requires a holistic view of energy and mobility. As demonstrated by the “Bidirectional Load Management” (BDL) project, electric vehicles, capable of both drawing and feeding back power, present diverse potential for market, grid, and system-friendly purposes, as well as for applications in the interest of end consumers, such as self-consumption optimization in photovoltaic applications. The technical implementation of the use cases has already been demonstrated in a protected project environment. However, some gaps and further developments for the transition to real operation remain open. These gaps concern both the technology and the legal, regulatory and process-related foundations and are to be closed in BDL Next.

Motivation

With the enactment of the Climate Protection Act, which came into effect on August 31, 2021, the German government has intensified the goals for achieving climate neutrality. By the year 2045, Germany must achieve climate neutrality, and until then, annual reduction targets apply to each sector. In the transportation sector, this particularly entails a transition to electric drives to reduce annual emissions. This must be accompanied by the further expansion of renewable energies to make the power sector independent of fossil fuels and to achieve climate neutrality in this sector as well.

The transition to electric drives and the expansion of renewable energies bring multifaceted challenges on both the energy system and power grids, as well as on the side of the automotive industry and users. Some of these challenges can be addressed by thinking across sectors and developing solutions collaboratively. New components, software solutions, and processes are needed for their integration, along with defining the interplay of various market participants and manufacturers.

Project Objectives

The goal of the BDL Next project is to design mass-market technologies and processes for bidirectional charging. To achieve this, it is initially necessary to address weaknesses along the effectiveness chain implemented in the predecessor project BDL. Subsequently, the systems should be more closely integrated with the ecosystem of customers and established processes in the energy industry. This includes grid-friendly operation of vehicles, such as through the use of dynamic grid tariffs or other coordination mechanisms at the low-voltage level, to avoid jeopardizing the rapid expansion of electromobility due to constraints in the power grid. Only in this way can bidirectional electric vehicles be fully integrated into energy markets as part of a robust and secure power grid.

On the other hand, vehicle users must also be convinced through simple system interactions, monetary benefits, and potential CO2 savings. A comprehensive multi-stage pilot operation is therefore aimed at, with the goal of ensuring the seamless integration of even more complex multi-use applications. Initially, some vehicles from the predecessor project will be used to implement new processes, strengthen existing processes, and further optimize various systems before transitioning to bidirectional production vehicles to demonstrate the mass-market viability of the technology.

Project Structure

The project is structured into 10 work packages (APs), outlined in Figure 1. In AP 1, led by FfE, the initial focus is on establishing the common foundations of potential use cases along with detailed use case definitions. Subsequently (AP 2 and 3), the systems are further developed for technical aggregation, and the necessary interoperable communication between the systems is defined and implemented. At the beginning of AP 3, a common overall system architecture is developed collaboratively across stakeholders. Building on this, APs 4-6 address network, system, and market integration. Ongoing coordination and exchange needs exist between the described APs 2-6. The practical implementations and developments culminate in a joint field trial for the demonstration and improvement of the solutions developed. APs 8 to 10 constitute the scientific support and synthesis for the project.

The FfE’s project contents

• Expansion of Use Case Methodology to include multi-use
• Implementation of grid state estimations and predictions
• Processing of measurement data
• Network expansion costs in scenarios with different Use Case combinations
• Realistic assessment of revenue potentials in various Use Cases and Multi-Use scenarios
• Analysis of systemic impacts of bidirectional charging
• Interactions between the network, market, and system for the identification of optimal Use Case combinations.

Methodology

The contents of the FfE, as one of the four research institutions in the BDL Next project, are primarily located in the work package for accompanying research on network impacts, system, and market integration.

As the lead of the consortium, the FfE will also contribute its methodological expertise in Use Case development at the beginning of the project. In comparison to the predecessor project or the unIT-e² project, methodological advancements in representing Use Case combinations are being developed at both the conceptual and technical levels. This is done to highlight synergies and interferences between different use cases. The resulting system diagrams and sequence diagrams aim to enhance understanding of the issues and provide a structured foundation for the subsequent technical development phase.

The FfE will develop forecasts for the grid integration of electromobility, enabling comprehensive planning of network utilization. Machine learning methods will be developed, evaluated, and applied to determine and predict the network state, allowing for grid-friendly use cases. Furthermore, customer behavior predictions will enable the utilization of electric vehicle flexibility without restricting customers.

Additionally, the FfE will analyze resulting network expansion needs for various scenarios using the FfE model GridSim. Different use cases will be simulated in representative models of low-voltage networks, and their impacts will be analyzed. The model expansion will allow for the calculation of network expansion needs for different network models, examining relevant indicators and threshold violations.

To achieve a realistic assessment of bidirectional charging revenues from the user’s perspective, revenue-oriented optimization will be performed in the actor model eFlame, assuming a rolling forecast horizon. Actors will optimize based on forecasts rather than historical data. This approach aims to provide a more realistic evaluation of multi-use and the revenue potentials of energy communities, in addition to assessing individual use cases.

For the study of systemic impacts of bidirectional charging, a realistic scenario with the inclusion of resource scarcity in the energy system model ISAaR will be modeled. The interaction of future hydrogen production and provision in the energy system will be analyzed, comparing it with the added value of bidirectional charging flexibility.

Furthermore, the FfE will address the central research questions arising from the comprehensive integration of bidirectional vehicles into the three different domains: network, market, and system. This integration effort requires not only considering the domains in isolation but also planning for a stronger interconnection concerning the model representation at FfE through the models eFlame, GridSim, and ISAaR.

Funding

The research project is funded by Bundesministerium für Wirtschaft und Klimaschutz (BMWK) (Funding Code: 01MV23013A, 01MV23013F). The three-year pilot project is led by the German Aerospace Center (DLR).