Electromechanical Analysis of Low Voltage Faults in a Magnetically Coupled Synchronous Generator Set

This paper investigates the magneto-mechanical performance of a magnetically coupled, engine driven synchronous generator set exposed to a severe low voltage grid fault. A multi-physics model of a generator, coaxial magnetic coupling and diesel engine is subjected to a 100% voltage drop scenario and the mechanical response is analysed. The peak coupling torque is significantly lower than that of a generator set coupled with a standard rubber flexible coupling, but the time required for generator to grid resynchronisation is increased. As a result, the machine shafts are protected from severe stress transients that can lead to structural failure. An oversized coaxial magnetic coupling is also analysed to determine the relationship between peak coupling torque and fault ride through performance.