On single-phase operation of three-phase synchronous generators

Classical synchronous generators have been used for decades in the field of power generation. The traditional manner of operation of these systems is the balanced, three phase configuration. However, recently there has been an interest in re-configuring consolidated, commercial, three phase generators to operate in single phase operation. A main driver for this phenomenon is the aim of manufacturers to extend their range of products for minimum development cost. Such an approach however brings a number of design challenges, especially in terms of the elevated damper cage currents and the negative sequence currents, when a 3-phase machine is ‘forced’ to operate in 1-phase. This paper therefore investigates and analyses these challenges. Considering a commercial, 3-phase, 400 kVA alternator. Detailed models, validated against experimental validation in 3-phase operation are first obtained. The machine is then re-configured to single phase operation. This paper proposes and shows how a suitable single phase loading can be found for 3-phase generators operating in single phase.