Temperature Prediction for 3 MW Wind-Turbine Gearbox Based on Thermal Network Model

Focusing on the investigation of a 3 MW wind-turbine gearbox, this paper's aim is to address the challenge of turbine shutdown due to the internal oil temperature exceeding its limits. Additionally, there is the difficulty in measuring the internal temperature. To tackle these issues, a thermal network model for the entire gearbox was developed. This model is based on an analysis of the thermodynamic behavior of the three-stage transmission in the wind-turbine gearbox and internal oil-spray lubrication. Through this model, thermal balance equations were established to predict the steady-state temperatures under different operating conditions. This study delved into the calculation methods for the power loss of heat sources in thermodynamic balance equations and the calculation methods for different types of thermal resistance between nodes, forming an adapted computational process. Applying this model, simulated analyses yielded temperatures at various nodes and bearing temperatures under different operating conditions. These results were compared with actual SCADA data, and steady-state thermal simulations of the high-speed stages were conducted, demonstrating the model's effectiveness in predicting steady-state temperatures for a large-megawatt wind-turbine gearbox. Furthermore, the model-based analysis explored the impact of the oil spray parameters on the gearbox temperature, providing a theoretical foundation for further anticipating overheating malfunctions and optimizing the internal cooling systems.