Simulative investigation of the load propagation in a wind turbine drive train during a power converter fault

Highly dynamic load situations in the drive train of wind turbines can occur during operation as a result of faults in the electrical grid or damage in electrical components. The dynamic loads can lead to damage or increased wear in the drive train components. At the Center for Wind Power Drives a wind turbine research nacelle has been set up in the course of a national project. Extensive experiments with this research nacelle have been conducted with the corresponding 4 MW test rig. Furthermore multi body simulation (MB S) models of the nacelle and the test rig have been developed and validated by experiments with load cases defined in the IEC 61400. Among other experiments, a test with a highly dynamic load situation in case of a power converter fault has been conducted. For that particular load case a power converter short-circuit has been emulated. This test's results show significant high torque reversals inside the drivetrain. This paper focuses on the implementation of the measured dynamic torque excitation in the existing MBS model in order to investigate the calculated torque load propagation from the high speed side to the low speed side of the drive train. The MB S model delivers further insight into the torque load propagation by providing the torque on the intermediate speed shaft (IMS) which could not be measured on the test bench. It is shown that the highly dynamic torque ripple is filtered out mainly in the spur gear stage from the HSS to the IMS.