Energy systems are becoming increasingly complex and include a growing proportion of distributed energy resources (DER) such as photovoltaic systems, wind turbines or energy storage units.
The challenge is to coordinate these components in order to ensure stable power supply of critical equipment in microgrids such as hospitals or critical industrial processes. As it is difficult or even impossible to test these components in a real-life setting, the components are hooked into a simulated microgrid and put through their paces in a safe hardware-in-the-loop (HIL) environment. New trends in HIL testing of microgrid and DER controllers were the topic of a workshop at the Massachusetts Institute of Technology, which was organised by the MIT Lincoln Lab and sponsored by the Massachusetts Clean Energy Center. AIT demonstrated its DER controller concept on a HIL platform provided by Typhoon HIL, an international market and technology leader in this field.
Successful demonstration at MIT
“Reliable control of distributed energy resources is of special importance for microgrids, says Zoran Miletic, Senior Engineer at the AIT Center for Energy. If the main grid fails, due to a hurricane for example, the microgrid should continue to supply critical equipment such as servers or emergency rooms with energy provided by distributed energy resources like solar systems or batteries.” This situation must be simulated in a HIL environment. The new DER controller developed by AIT has successfully demonstrated that it is able to simulate all these energy resources in real time and can thus be used for grid integration studies, research and testing of HIL microgrids.
The novel controller also forms an integral part of the Smart Grid Converter (SGC) developed by AIT. Smart power converters act as the intelligent interface between distributed energy resources and the grid, making them a key enabling technology for future energy systems. AIT's SGC can interactively switch between two grid modes: it can operate as a solar system or energy storage converter when connected to the grid or alternatively emulate the grid in the event of grid failure. “Today’s solar inverters will disconnect when the main grid breaks down”, says Zoran Miletic. “Our converter is able to recognise this condition and continues to supply power to critical loads during power outages.” A prototype of this new development will this year be presented at PCIM and Intersolar, two major international exhibitions for the power electronics and renewable energy industries.
Cooperation with industry and high-level research
The DER controller is the result of a successful collaboration between AIT and Typhoon HIL. The two companies have already worked together in previous projects, developing a commercial tool for pre-certification of solar inverters for grid codes of different countries. It allows manufacturers to run standardised tests in-house and has enabled leading solar companies in Austria and abroad to shorten time to market for their products. To keep abreast of international developments, AIT will also continue its cooperation with key research players. "The MIT Lincoln Lab has recognised the potential of our smart grid controller solution for their microgrid testbed", says Wolfgang Hribernik, Head of Electric Energy Systems in the Center for Energy, confirming plans for joint future projects.