Active and reactive power operational region for grid-interactive cascaded h-bridge multilevel converters

摘要

Cascaded h-bridge (CHB) multilevel converters are being considered as a promising option for interfacing renewable energy resources with the grid, due to their modularity, scalability, and increased efficiency when compared to traditionally used two-level inverters. When used as grid interfaces, CHB converters should be capable of controlling the injected active and reactive power while also satisfying operating criteria such as grid standards, e.g. IEEE 519. This paper aims to identify practically available operating points in the PQ plane when using a grid-interactive CHB converter, and to determine the factors which prevent utilization of other operating points. This work (i) provides distribution engineers with information regarding the active and reactive power which can feasibly be generated by a grid-interactive CHB converter, (ii) creates a framework for assessing operating point trajectories when altering the steady-state operation of grid-tied CHB converters, and (iii) provides a basis for selecting and modifying steady-state PWM generation techniques in order to meet desired performance criteria. Simulation data are presented to verify the findings of this work.