Improvement of three-phase unbalance due to connection of dispersed generator by damper windings of synchronous generator

It is well known in the numerical simulation of synchronous generator that the damper winding contributes to suppress the three-phase circuit unbalance in power systems. However, experimental study has not been performed yet. In this paper, authors verify experimentally the suppression of the three-phase unbalance by the damper windings. In order to simulate the three-phase unbalance, a 470 W dispersed generator of single-phase-two-line type is connected to a three-phase laboratory-scale power system that includes a 6 kVA synchronous generator. Authors measured and analyzed line voltages and currents as well as damper bar currents both with and without dispersed generator. The influence of damper windings to the unbalance of three-phase circuit is also investigated. The results show that the damper winding contributes to improve the three-phase unbalance.