Effect of commutation failures on torsional vibrations of a turbine generator nearby an hvdc link

For an HVDC system, it is studied the torsional vibrations induced on the inverter side turbine generators due to a rectifier side ac faults. It is found there may be up to several times difference in the torsional torques induced at the turbine shafts and blades for the same fault, depending on the inverter commutation behavior. Further, if a single-phase-to-ground fault takes place with the commutation failure, it might cause a more serious impact on the turbine generator unit than a three-phase-to-ground fault without commutation failure.