The Parallel Operation of the Output Three Phase Inverters in the MicroGrid

The article concentrates on the parallel operation of output the three-phase power inverters in MicroGrid. The MicroGrid for an electric train is considered that contains two output three-phase inverters with a total power 400 kVA. Analytic expressions for determination of a required phase and output voltage amplitude of the three-phase inverters are obtained. The problem related to current rushes appearance when the output three-phase inverter connected to the MicroGrid is shown. For solving this problem, the control algorithm of the output three-phase inverters with the use of two proposed control modes (PLL-mode and Droop-mode) was developed. It is shown that the combination of the developed PLL-mode and Droop-mode allows excluding the output current rushes and provides an equable output power division between the three-phase inverters at the level of 5%. This article is of interest for power electronics engineers who develop MicroGrid for stand-alone power supply systems with renewable electric power sources, and also for onboard power supply systems of aircrafts, watercrafts and electric trains with the use of several parallel operating output three-phase power inverters.