Performance of Distributed DC Power System using Quasi Z-Source Inverter Based DC/DC Converters

DC microgrids for power combining and distribution are of interest in many applications due to their high efficiency, relatively low cost of installation and operation, freedom from harmonic and reactive power and stability. The quasi Z-Source Inverter (q-ZSI) is a particularly promising circuit for DC Distributed Power System (DPS) because of its unique buck-boost characteristics, high power handling capability and inbuilt fault tolerance. The buck-boost capability reduces the number of power conversion stages required and provides ride-through capability during voltage sag and swells from the grid. However, the performance of q-ZSI in DC DPS under varying sources and load conditions has not previously been investigated. We present analysis and simulation of 400V DC DPS by placing q-ZSI converters in parallel under widely varying input and output conditions. An automatic master-slave control strategy was used to share the load current among parallel converters. The results verify the benefit of q-ZSI converters in DC DPS and show that DC DPS can have good transient and steady state response and is capable of maintaining stiff DC voltage at the common bus with minimal interaction.