Smart grid in real-time test: the new Digital Grid Lab of Fraunhofer ISE

Europe’s power grids are undergoing a profound transformation as part of the energy transition: from large-scale power plants to distributed, intelligently networked, digitally controlled, low-emission and diverse units. Millions of small feed-in plants and storage facilities, new consumers and players are entering the scene, which have to be managed at the lower grid levels. In the future, the accustomed high quality of supply can only be achieved with the digitalization of the grids and intelligent operational management concepts. The Fraunhofer Institute for Solar Energy Systems ISE has now put its new Digital Grid Lab into operation, where the necessary components, grid control concepts and operation management strategies are being tested.

“Integrating both centralized and fluctuating distributed systems and maintaining grid stability is a major challenge for grid operators. With the Digital Grid Lab, Fraunhofer ISE is expanding its expertise in the area of grid simulation and can view the grid and the communication within it in real time,” explains Prof. Christof Wittwer, Division Director Power Electronics, Grids and Intelligent Systems at Fraunhofer ISE.

Hardware-in-the-loop simulations in real time

At the heart of the new laboratory are the six powerful hardware-in-the-loop (HIL) computers: they allow power grids with up to 2000 nodes to be modelled and their behaviour to be tested at high temporal resolution. For devices or systems at grid nodes, but also for self-sufficient micro grids, smart districts and distribution grids, critical grid situations can also be simulated in this state-of-the-art test environment without endangering the real power grid. Eight flexibly switchable power amplifiers with a total output of 800 kVA allow this simulated network situation to be applied to a test object or batteries and generators (e.g. photovoltaic systems) to be simulated in hardware. The modern infrastructure allows the consideration of AC or DC networks.

“The digital twin on the HIL computer is very flexible to configure thanks to a library of models. We can simulate power grids of different sizes and voltage levels and simulate both residential and commercial power systems. The twin enables the evaluation and optimization of components, energy management systems and communication standards in a safe, realistic environment,” says Dr. Bernhard Wille-Haußmann, who heads the laboratory as group manager for network operation and network planning.

The Digital Grid Lab is also equipped with a control room in which new control algorithms and operating strategies for smart grids are tested using artificial intelligence methods. The hardware-in-the-loop computer takes on the role of the digital twin here and models a power grid including its communication for the control room. This allows new control concepts to be evaluated in a realistic environment under critical conditions without any risk to real grid operation.

Tests for intelligent electromobility

The infrastructure described allows the testing of various energy technology components, such as battery systems, combined heat and power plants or heat pumps. For the launch of the laboratory, the experts at Fraunhofer ISE have developed the digital twin of an electric vehicle. With this, they emulate an electric vehicle or even an entire vehicle pool with its power flows and its communication with the charging station. In this way, different types of charging stations can be tested with regard to their grid feedback (according to grid connection guidelines VDE AR 4100/4105) and in interaction with intelligent metering systems and energy management systems. In addition to grid conformity, this also includes the adaptation of the charging current to external requirements, e.g. by the grid operator or charging station operator. The Digital Grid Lab allows testing of the grid conformity and communication of charging plugs and modes according to the IEC 62196, IEC 61851 and ISO 15118 standards. The test of charging stations thus includes communication tests for the entire signal chain and evaluations of the device behavior to external market and control signals. Since the test stand in the Digital Grid Lab is also connected to numerous real charging stations, the compatibility testing of charging management concepts can be carried out in a manufacturer-neutral and safe manner.

Virtual tour of the Digital Grid Lab

Follow this link for a virtual tour of the Digital Grid Lab with audio commentary and information on test equipment and opportunities.