A High-Performance 2×27 MVA Machine Test Bench Based on Multilevel IGCT Converters

In this paper, a high-performance 22 MW/27 MVA test bench using a pumpback topology is introduced for testing electrical machines. It proposes a cost-effective concept that works reliably even with a weak grid. A paralleling concept of two three-level integrated gate-commutated thyristor (IGCT) converters is presented. I generates a five-level pulse pattern with low harmonic distortion at 600-Hz carrier frequency and 80-Hz load frequency. The selected magnetic device minimizes the circulating current, which ensures the full power utilization of IGCT converters. Moreover, the control concept works reliably at 7.5 times of the carrier-to-load frequency ratio while there is a sine filter and a variable-frequency transformer between the converter and load machines. This test bench has been experimentally validated at the customer site.