Decentralized synchronization of parallel inverters for train auxiliaries

A decentralized controller for the synchronization of two remote parallel voltage source inverters used to supply train auxiliaries is presented. A modular hybrid dynamic model of the entire power electronic apparatus is constructed; possible unbalanced line and load impedances are also considered. The power sharing between the converters is obtained by designing a droop controller based on local measurements of active and reactive powers. The controller is completed with a synchronous reference frame Phase Locked Loop which detects the local line voltage phase. The inverters synchronization allows a good power sharing in steady state and avoids the typical current overshoots due to the activation of one converter when the other is already operating. The controller effectiveness is tested in a realistic simulation scenario.