Parallel-connected inverters with separate controllers having impedance current regulators

Abstract

A control system () for a power converter () designed to convert DC power from a source () such as a battery, flywheel or fuel cell into AC power. The control system includes an impedance current regulator () for providing an impedance current signal to a summing unit () where it may be combined with real and reactive current command signals provided from respective sources (). The resultant current signal provided by the summing unit is provided to a voltage correction unit () that uses the resultant current signal in developing a correction voltage signal provided to the power converter. The correction voltage signal contains information used by the power converter in adjusting the real and reactive currents in its output AC power based on the ability of the AC power network to accept changes in current. Multiple power converters having the control system of the present invention may be connected in parallel to a single AC load or multiple AC loads, without the need for a separate control system interconnecting the power converters. The control system may be advantageously incorporated into a distributed generation network and in uninterruptible power systems, whether or not such systems are included in a distributed generation network.