On the Multi-Body Modeling and Validation of a Full Scale Wind Turbine Nacelle Test Bench

Ground testing of full-scale wind turbine nacelles has emerged as a highly favorable alternative to field testing of prototypes for design validation. Currently, there are several wind turbine nacelle test facilities with capabilities to perform repeated and accelerated testing of integrated turbine components under loads that the machine would experience during its nominal lifetime. To perform accurate and efficient testing, it is of significant interest to understand the interaction between coupled test rig/dynamometer and nacelle components, particularly when applying extreme loads. This paper presents a multi-body simulation model that is aimed at understanding the responses of a coupled test rig and nacelle system during specific tests. The validity of the model is demonstrated by comparing quasi-static and dynamic simulation responses of key components with experimental data obtained on an actual 7.5 MW test rig. A case study is conducted to analyze a transient grid-loss event; a Low Voltage Ride Through (LVRT) test on the dynamometer and drivetrain components. It is shown that the model provides an efficient way to predict responses of the coupled system during transient/dynamic tests before actual implementation. Recommendations for mitigating the impact of such tests on the test bench drive components are provided. Additionally, observations of differences between transient events in the field and ground based testing are made.