Loading methodology and dynamics analysis of the digital-servo hydraulic cylinders group in large wind turbine drivetrain test bench

As the capacity of wind turbines continues to increase, wind turbine drivetrain test benches are facing several challenges. These include loading inaccuracies for extreme loads, loading incompatible for multi-MW wind turbines, ever-shortening research and development cycles, and complex dynamic behavior involving vibration loads. In this article, a digital-servo hydraulic cylinders group (DSHCG) is proposed to address the problems of control inaccuracy and incompatibility for multi-MW wind turbine testing. The working area of the DSHCG can be adjusted in real-time to meet loading requirements, and an iterative solving algorithm is proposed to handle the multivariate nonlinear non-torque load decomposition of the DSHCG. To investigate the loading methodology and dynamic characteristic of the DSHCG-based drivetrain test bench, a Matlab-AMESim-Adams co-simulation model is established to simulate the full-scale component response without requiring full-scale field tests. The results demonstrate that the proposed loading methodology can accurately simulate typical field wind loads, as the non-torque load reproduction errors for three power levels of wind turbines are within 9 %. Furthermore, two wind cases are conducted on a 20 MW wind turbine drivetrain test bench, and the dynamic analysis results show that the vibration displacement of the loading disk and bearing load increases under high wind speed.