in wind power projects
20 kW drivetrain
250 kW drivetrain
250 kW Brushless DFIG system
We have successfully built and tested a large-scale Brushless DFIG and its accompanying frequency converter and control systems. The generator is rated at 250 kW and has a speed range from 350 to 680 rpm. A third rated frequency converter was designed and developed by our engineering team, enabling connection to the grid. A control system was developed to perform the control requirements common in wind turbine systems.
The system was highly instrumented and tested on a test bench with mechanical loads provided by a driving motor.
Comprehensive tests were carried out including parameter identification of the generator, steady-state performance measurements, controller's dynamics and stability verifications, long-run thermal tests, and grid fault low-voltage ride through (LVRT) performance characterization. Key tests were inspected by a third party. Overall, the performance was close to design expectations and an efficiency of more than 95% was achieved at full power which shows competitive performance as compared to an equivalent-size DFIG. Fast and stable dynamic response was achieved by the control system enabling the exertion of full power from no-load in less than 1.5 second. The LVRT test results show a significant improvement as compared to the DFIG, eliminating the need for an additional complex hardware (e.g. crowbar protection) for the converter.
Test results have confirmed the correct operation of the Brushless DFIG, with current and flux densities close to expected values. The 250 kW Brushless DFIG is, to the best of our belief, the largest machine of this type ever constructed. Testing the 250 kW Brushless DFIG shows that the expected performance is achieved and the machine can be controlled stably. The most important conclusion is that a large scale Brushless DFIG is practical and is scalable upwards.