Success Story
Enhancing testing capabilities with Power Amplifiers
Preparing today the electrical systems of tomorrow
The EDF Group is a leading player in the European energy market, active across the entire electricity value chain: generation, transmission, distribution, trading, and energy sales. Its ambition is to become the benchmark electricity provider in the world of tomorrow.
The primary missions of EDF Group’s Research and Development Division are to improve the performance of operational units, identify and prepare future growth drivers, and anticipate the major challenges of the 21st century. The transition toward more intelligent electrical systems is a cornerstone of the shift to a carbon-free energy economy.
Concept Grid: A Full-Scale Experimental Power Network
Concept Grid is a real, full-scale electrical network extending from the source substation to the end user’s meter. The medium-voltage (MV) network includes 5 km of underground and overhead lines, complemented by an additional 120 km modeled using RLC elements. The neutral grounding regime can be modified on demand.
Seven distribution substations supply a 10 km low-voltage (LV) distribution network. The platform integrates model homes and photovoltaic installations and allows for flexible network configurations, enabling controlled operation with or without distributed generation.
By combining a real-time simulator with a power amplifier, Concept Grid can generate complex production and consumption scenarios under highly realistic conditions.
The platform is equipped with fiber-optic and Ethernet communication networks, supporting a wide range of communication protocols. It also enables testing of power line communication (PLC) technologies and the implementation of control commands compliant with the IEC 61850 standard.
Power Hardware-in-the-Loop at EDF: Insights from the Field
We had the pleasure of speaking with Nikola Stankovic, PhD, R&D Engineer in Real-Time Simulation and Grid Testing at EDF. He shared insights into how Power Hardware-in-the-Loop (PHIL) testing began at EDF and how power amplifiers are used to enhance grid flexibility and support a wide range of testing scenarios.
How it all started
The stability of a power system depends on the stability of each of its components—an observation that also applies to Power Hardware-in-the-Loop simulations. Within a PHIL setup, the power amplifier and its interfaces are integral parts of the loop and directly influence both the dynamic behavior and overall system stability.
The concept of integrating a PHIL setup into EDF’s laboratory emerged during the laboratory’s design phase, back in 2012, and was envisioned as a core building block from the outset.
In environments without access to a physical grid, grid behavior must be simulated using a real-time simulator to enable real-time testing. At EDF, however, we operate a real experimental grid. Our objective was therefore not to replace the grid, but to enhance its testing capabilities. In this context, the power amplifier serves as a complementary element within the overall system architecture.
EDF’s experimental grid operates at 50 Hz, with voltage levels of 20 kV (medium voltage) and 400 V (low voltage). While this setup is ideal for many tests, it has inherent limitations. For example, testing equipment designed for the U.S. market requires a 60 Hz supply, and certain scenarios—such as voltage dips or the injection of specific harmonics—cannot be realized using the existing grid alone.
In such cases, a power amplifier acts as a grid-forming device, enabling precise control over voltage, frequency, and waveform characteristics. Combined with a real-time simulator, power amplifiers significantly expand testing flexibility and enable more versatile and advanced PHIL simulations.
The Importance of Speed and Versatility
From the early stages, EDF relied on power amplifiers, initially using linear amplifiers. While these met early requirements, testing demands evolved rapidly. Initial tests focused on electric vehicle chargers in the 10–20 kW range, but power levels soon increased to 350 kW, 400 kW, and eventually to the megawatt scale.
Linear amplifiers could no longer meet these requirements due to limitations in power capacity and efficiency. As a result, switching power amplifiers became the preferred solution, offering significantly higher power levels and improved efficiency while remaining competitive in terms of bandwidth.
„High bandwidth is critical, as it directly impacts system dynamics, response speed, and the overall performance of PHIL simulations. Equally important are digital interfaces, which eliminate parasitic effects commonly associated with analog signaling and ensure accurate reference signals between real-time simulators and power hardware.”
As a laboratory conducting a wide variety of tests, EDF requires equipment that is both fast and highly versatile. To meet diverse and evolving testing requirements, EDF relies on state-of-the-art power amplifiers capable of supporting the most demanding experimental scenarios.
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