5 Megawatt Medium Voltage Direct Current Test System
Researchers at the Future Renewable Electric Energy Delivery and Management (FREEDM) Systems Center, a National Science Foundation (NSF) Engineering Research Center (ERC) based at North Carolina State University in partnership with Arizona State University, Florida State University (FSU), Florida A&M University, and the Missouri University of Science and Technology, completed the installation and commissioning of a 5 megawatt (MW), 24,000-volt (V) direct current (DC) power test system that provides FREEDM with the ability to test novel medium voltage direct current (MVDC) electrical equipment and control algorithms in simulated real-world conditions. The system consists of four individual 6 kilovolt (kV), 1.25 MW converters that can be arranged in series, in parallel, or in any combination of connections to form an agile testbed for MVDC systems research.
Scientists can use the MVDC laboratory in combination with FSU’s Center for Advanced Power Systems’ (CAPS) real-time digital simulator (RTDS) to establish both power-hardware-in-the-loop (PHIL) and controller-hardware-in-the loop (CHIL) tests for validating smart energy solutions and micro-grid technologies. The reconfigurable nature of FSU-CAPS’ four converters, combined with the PHIL and CHIL capabilities of FSU-CAPS’ existing infrastructure, provides an ideal facility for testing the capabilities of novel equipment emerging from the FREEDM Systems Center. These discoveries follow the natural progression of wide band gap (WBG) power electronic technology, originally spearheaded within the FREEDM System Center, as it trends towards DC systems.
The development of Modular Multilevel Converter (MMC) technologies has accelerated the use of MVDC as a feasible technology with benefits not currently available from conventional Voltage Source Converter (VSC)-based systems. The recent co-emergence of MMC and MVDC systems affords new opportunities for micro-grid technologies, such as offshore wind farms or future Navy ship systems. MMC technology offers many benefits for electrical distribution, such as: lower device switching frequency despite high overall apparent switching frequency, low harmonic content, and small or no filter requirement on the DC side. The technology also provides current limiting capability during faults, and fast recovery from alternating current (AC) or DC short circuit.