Power system stabilizer for comunicationless parallel connected inverters

In this paper, small-signal stability issues of low-voltage parallel-connected voltage source inverters without control interconnections are addressed by means of dynamic analysis and experimentations. The studies performed showed that the parallel system damping is severely reduced when the traditional droop method is employed and the cabling is long. This paper proposes the application of the PSS (Power System Stabilizer) action to the control of parallel inverters in order to increase the stability range concerning the connection impedance composition R/X. It is shown that the PSS action can significantly improve the system damping. Experimental results for two 1kVA inverters in parallel sharing a common load are presented and corroborate the presented ideas.