Northern Power Systems, Inc.

Belvin Sewell Freeman

Jeffrey K Petter

A system and method are disclosed for controlling DC to AC power converters (inverters) that are operated as voltage sources and are paralleled on the AC side. This method allows for controlling frequency while sharing real power. The disclosed method requires no communication between inverters for proper load sharing, thus enhancing reliability of a system of parallel inverters. The only signals required for control are the AC voltage and frequency and their reaction to the inverter output current. The present invention allows a multiplicity of inverters or active rectifiers to share power in relation to their share of the available power capacity of the system. This makes it possible to parallel DG sources with various response times while they are connected to either a utility grid or in a stand-alone power network with no communications required between inverters. The addition of communications to the system allows the dispatch of energy for economic reasons and to fine tune load balance. Communications can be used for systems status and maintenance but is not required for reliable short-term operation.

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Moretown, VT, United States of America

Belvin Sewell Freeman