Multifunctional megawatt scale medium voltage DC test bed based on modular multilevel converter (MMC) technology

Abstract

The recent development of modular multilevel converters (MMC) provides new opportunities for medium voltage DC (MVDC) systems for all electric ship design and offshore wind parks. Therefore, the Center for Advanced Power Systems at Florida State University has recently commissioned a new MVDC power-hardware-in-the-loop laboratory rated at 5 MW at DC voltages between 6...24 kV. The new lab features four individual MMCs, each composed of 36 full-bridge cells, and capable of delivering 210 A at 0...6 kV. This paper describes the entire system in detail, including the advanced current and voltage control concepts along with the state of the art digital control hardware. Selected commissioning results demonstrate the performance of the system under dynamic conditions and provide comparison with simulations obtained from a corresponding controller hardware-in-the-loop setup which is also described in the paper.