Fault Detection and Ride-Through Operation Method for CHB Converter Based STATCOM Integrating Controller Information and Measurement Data

This paper presents a simple detection and ride-through operation method for single IGBT open-circuit faults in cascaded H-bridge STATCOMs. The method requires only the addition of a DC component controller to the current inner loop, in conjunction with the existing control loops for specific harmonics and voltage balance, to achieve rapid detection and localization of the faulty IGBT. In this approach, the controller also serves as a system state monitoring loop, eliminating the need for additional sensors and computational processing units. Upon fault localization, the paper further provides a reliable fault ride-through method. During the ride-through operation phase, the faulty H-bridge module can switch to half-bridge operation, with the DC offset voltage compensated by the remaining healthy modules. The effectiveness of the proposed method is validated through experiments.