Electrical faults can lead to transient and dynamic excitations of the electromagnetic generator torque in wind turbines. The fast changes in the generator torque lead to load oscillations and rapid changes in the speed of rotation. The combination of dynamic load reversals and changing rotational speeds can be detrimental to gearbox components. This paper shows, via simulation, that the smearing risk increases due to the electrical faults for cylindrical roller bearings on the high speed shaft of a wind turbine research nacelle. A grid fault was examined for the research nacelle with a doubly fed induction generator concept. Furthermore, a converter fault was analyzed for the full size converter concept. Both wind turbine grid connection concepts used the same mechanical drive train. Thus, the mechanical component loading was comparable. During the grid fault, the risk of smearing increased momentarily by a maximum of around 1.8 times. During the converter fault, the risk of smearing increased by around 4.9 times. Subsequently, electrical faults increased the risk of damage to the wind turbine gearbox bearings, especially on the high speed stage.
Three phase short circuit power converter faults in wind turbines (WT) result in highly dynamic generator torque reversals, which lead to load reversals within the drivetrain. Dynamic load reversals in combination with changing rotational speeds are, for example, critical for smearing within roller bearings. Therefore, an investigation of the correlation between three phase short circuit converter faults and drivetrain component failures is necessary.Due to the risk of damage and the resulting costs, it is not economically feasible to extensively investigate three phase short circuit converter faults on test benches. Valid WT drivetrain models can be used instead. A WT drivetrain model, which has been developed and validated in a national project at the CWD, is used and a three phase short circuit converter fault is implemented. In this paper, the resulting torque load on the drivetrain for a three phase short circuit converter fault in rated power production is presented. This converter fault leads to a highly dynamic reversing electromagnetic torque which exceeds the rated torque by a factor of three. As a result the load on the rotor side high speed shaft (HSS) bearing oscillates and increases by around 15 per cent compared to rated power production. Simultaneously the rotational velocity of the HSS oscillates with an amplitude of 10 rpm. Therefore an increase in the risk of smearing is expected.
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 (MBS) 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 MBS 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.