Performance of Distributed DC Power System using Quasi Z-Source Inverter Based DC/DC Converters Yam P. Siwakoti Department of Electronic Engineering, Macquarie University, NSW-2109, Australia. Email:
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Graham E. Town Department of Electronic Engineering, Macquarie University, NSW-2109, Australia. Email:
[email protected]
Abstract—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 buckboost 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. Index Terms— DC/DC Converter, Distributed DC Power Systems, Quasi Z-Source Inverter, Load Sharing, Automatic Master-Slave Current Control.
I. INTRODUCTION DC power distribution system have number of desirable features, including elimination of heavy transformer, absence of reactive power and harmonics, fewer conversion stages, and possibility of integration of small distributed generation units e.g. photovoltaic array, fuel cells, wind generator [1-3]. Additionally, distributed power system with several low power converter modules in parallel offers number of advantages over a high-power centralized power supply due to increased reliability, redundancy, better thermal management and modularity. Consequently DC DPS are of interest for applications such as data servers farms and hybrid power systems [4-6]. A variety of converters, especially Voltage Source Inverter (VSI) based DPS topologies have previously been reported which aim to combine power for large scale power systems [4]
& [7]. However, VSI are buck type converter in their linear modulation range (m
