Integrated power conditioning system for MTG and SOFC with improved power quality

This paper presented a power conditioning system integrating microturbine (MTG) and solid oxide fuel cells (SOFC) for auxiliary power units (APU) applications. Cascaded multilevel inverters are applied to achieve the power conversion between MTG and SOFC. Two different switching schemes, i.e. independent switching scheme and unified switching scheme, are proposed to eliminate low-order harmonics of output voltage, improve power quality and increase system efficiency. The independent switching scheme can implement the constant power distribution between MTG and SOFC under different load requirement. The unified switching scheme can achieve lower total harmonic distortion (THD) than the independent switching scheme but the angles range are limited. A control system with the hybrid two switching schemes is designed to achieve flexible power distribution, steady ac bus voltage with different load and lower THD of voltage and current. The simulation results demonstrate that the proposed control system can effectively implement good performance of the proposed power conditioning system.