ABSTRACT:

A scheme for controlling parallel-connected inverters in a standalone AC supply system is presented. This scheme is suitable for control of inverters in distributed source environments such as in isolated AC systems, large and distributed uninterruptible power supply (UPS) systems, photovoltaic systems connected to AC grids, and low-voltage DC power transmission meshes. A key feature of the control scheme is that it uses feedback ofonly those variables that can be measured locally at the inverter and does not need communication of controlsignals between the inverters. This is essential for the operation of large AC systems, where distances betweeninverters make communication impractical. It is also important in high-reliability UPS systems where systemoperation can be maintained in the face of a communication breakdown. Real and reactive power sharing between inverters can be achieved by controlling two independent quantities: the power angle and the fundamental inverter voltage magnitude. Simulation results are presented