Detection and Mitigation of Fault in 11-Level Converter STATCOM

This paper introduces an approach to detect the existence of the faulted switch, identify which switch is faulty, and reconfigure the STATCOM. This approach is illustrated on an elevenlevel STATCOM and the effect on the dynamic performance and the total harmonic distortion (THD) is analyzed Many static synchronous compensators (STATCOMs) utilize multilevel converters due to the following: 1) lower harmonic injection into the power system; 2) decreased stress on the electronic components due to decreased voltages, and 3)lower switching losses. One disadvantage, however, is the increased likelihood of a switch failure due to the increased number of switches in a multilevel converter. Due to its unique topology, the Modular Multilevel STATCOM has many advantages but requires a sophisticated controller and puts higher requirements on simulation tools. A single switch failure, however, does not necessarily force an (2n + 1)-level STATCOM offline. Even with a reduced number of switches, a STATCOM can still provide a significant range of control by removing the module of the faulted switch and continuing with (2n − 1) levels.