Decentralized power generation: New Megawatt testing equipment for over-voltage ride through
To keep pace with the latest changes to grid codes and testing standards the facilities of Fraunhofer IEE‘s laboratory SysTec have recently been upgraded by an over-voltage-ride-through (OVRT) test container. The new testing equipment is designed to analyze the dynamic behavior of wind turbines, photovoltaic inverters and combined heat and power units during short time over voltages of the supply voltage. Since the revision of grid codes in fall 2018 riding through short-term voltage swells now also became a requirement for generating plants installed in regional and local distribution grids.
“Decentralized power generators have to cope with disturbances in the power system in a supporting an reliable way“, explains Dr. Philipp Strauß, deputy head of the institute and head of the division Systems Engineering and Distribution Grids at Fraunhofer IEE in Kassel. The institute performs the measurement of generating plants according to the requirements of the interface to the power grid for the socalled type-specific unit certificate. This certificate is prepared for each type, e.g. a combined heat and power unit (CHP) or a photovoltaic system, and precedes the certification of complete systems. If required, the modelling for the simulation of the entire plant can also be carried out. “Our laboratories are used for developing components and systems as well as for final accredited tests”, describes Strauß.
According to the recent revision of the German VDE grid codes the laboratories of Fraunhofer IEE were now completed with an over-voltage-ride-through (OVRT) test equipment for a maximum power of 6 MVA. Since 2011 Fraunhofer IEE is testing power generators concerning grid compliance including their fault-ride-through (FRT) behavior.
“The transformer-based, mobile test container was successfully developed in cooperation with KoCoS Engineering GmbH”, explains IEE project leader Nils Schäfer. The new OVRT test container allows generation of short-term over-voltage events of up to 140 % of nominal voltage. The OVRT as well as the UVRT container are designed for mobile utilization and can be deployed in field measurements. Both have a power capacity of 6 MVA and can be installed in the medium voltage level at 20 kV or 10 kV nominal voltage. The new testing equipment was successfully set in operation in summer 2019; first tests have been accomplished with CHP units.
Beneath testing of grid compliance and studies on grid dynamics, Fraunhofer IEE offers
services regarding conceptual design, development, implementation and operation of mobile testing equipment. Together with partners, services range from support and supervision to turnkey solutions.
The Fraunhofer IEE Test Center for Smart Grids and Electromobility (SysTec) in Fuldatal-Rothwesten (12 km north of Kassel) comprises an outdoor area of around 80,000 square meters with configurable distribution network sections and three laboratory areas for testing low and medium-voltage converters, combined heat and power plants, electrical machines and network equipment, systems for integrating electric vehicles and power storage devices into the network, and portable FRT test containers (UVRT and OVRT) for on-site use. SysTec includes the network integration (PNI) test laboratory, a test field for hybrid systems, a test laboratory for electrical machines and a hardware-in-the-loop (HiL) laboratory.
Dr.-Ing. Gunter Arnold
Phone +49 561 7294-244
Dipl.-Ing. Nils Schäfer
Phone +49 561 7294-244