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Video: Research Network Tests Direct Current In Use
2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-05-24 11:12
A DC network has recently been put into operation at the Flexible Electrical Networks (FEN) research campus, which is intended to serve as a test environment for DC voltage converters and protection technology. The background of the research network is the desire for more flexible electricity networks, explains the research campus. Conventional distribution networks are based on alternating current (AC), while the research network that is now in operation works with direct current (DC).
The advantages of DC networks:
- A higher degree of efficiency is achieved.
- Renewable energies mostly work on a direct current basis - so there is no conversion to alternating current.
- In addition, DC networks require components with considerably less material than conventional 50 Hz systems and are therefore more resource-efficient.
New DC-DC converter developed
In the coming years, the research network will connect the test rigs of the Institute for Power Generation and Storage Systems (PGS) at E. ON ERC and the RWTH Center for Wind Drives (CWD). In this test environment, new DC voltage converters and components, protection technology and operational management concepts are tested.
A new direct voltage converter (DC-DC converter) was specially developed for the network, which could be used as a key component for future intelligent direct voltage substations. Such DC voltage substations could arise, for example, as large collector fields for renewable energies and as battery storage, for example in quick-charging stations for electric vehicles or as industrial DC networks.
What can the DC converter do?
The DC-DC converter works according to the three-phase dual active bridge (DAB) principle, thus enabling a bidirectional, flexibly controllable power flow and at the same time offering galvanic isolation, which meets the requirements of future DC voltage networks. The converter will in future be part of an arrangement by the Institute for Power Generation and Storage Systems of several converters built in the same performance class at E. ON ERC.
While conventional megawatt class power converters in the PGS laboratory were equipped with an adapted control for operation, the medium frequency transformer with a nominal output of 5 MW was completely redeveloped and designed together with the industrial partners. The operating frequency of 1000 Hz increases the gravimetric power density by 15 to 20 times compared to a conventional dry mains transformer.
AC vs. DC
Why direct current is a real alternative
In the meantime, another DC-DC converter, which can deliver up to 7 MW, is already connected to the research network in order to be tested there under realistic conditions. With this new converter type for low energy losses, the switching of the high-performance semiconductors is supported with a resonance circuit. This can be compared to a pendulum that swings automatically between its end positions (the switch positions) and requires only minimal push to keep the process going.
The FEN research network was created as part of a public-private partnership between RWTH Aachen University with 16 participating professorships and 21 industrial partners. The Federal Ministry of Education and Research, on whose initiative the nine research campuses in Germany are based, supports them with the funding initiative "Research Campus - Public-Private Partnership for Innovations".