| Author: | Wei, Wei |
| Title: | Design of variable speed constant frequency generator |
| Degree: | M.Sc. |
| Year: | 2024 |
| Department: | Department of Electrical and Electronic Engineering |
| Pages: | 93 pages : color illustrations |
| Language: | English |
| Abstract: | The model of the doubly fed asynchronous generator was studied, and the pitch control of the wind turbine was understood. The doubly fed generator can efficiently convert energy in a wide range of wind speeds and improve power generation efficiency. In addition, it can adjust the blade angle through pitch control technology when the wind speed is low or high to ensure that the power generation system can operate stably. Compared with other types of generators, the comprehensive cost of the doubly fed generator and pitch control technology is low, including equipment cost and maintenance cost. The structure of the doubly fed generator is relatively simple, the pitch control technology is relatively mature, and the cost performance is very high. The doubly fed generator can respond quickly to wind speed changes, adjust the blade angle in a short time through pitch control technology, reduce the impact of wind speed fluctuations on the system, and ensure stable power output. By adopting doubly fed generators and pitch control technology, an efficient, stable and economical wind power generation system can be achieved. These solutions and selection reasons help optimize the performance and reliability of the generator set. Based on the above, the doubly fed generator and wind turbine generator set were selected in the design, the doubly fed asynchronous motor with a rated power of 1500kw and a rated voltage of 690V was selected in the design, and the wind turbine set with a rated wind speed of 11.5m/s was selected in the design. Before modeling, the main parameters of the doubly fed asynchronous generator are determined, such as stator voltage, rotor voltage, stator resistance, rotor resistance, stator inductance, rotor inductance, mutual inductance, etc. Based on the d-q axis theory, the parameters are decoupled by Clarke transformation and Park transformation, and the mathematical model of the doubly fed asynchronous generator is established, including the voltage equation, flux equation and mechanical motion equation. The vector control strategy based on the stator voltage and flux direction is used to determine the reference coordinate system by measuring and calculating the phase and amplitude of the stator voltage. In this coordinate system, the stator voltage is decomposed into two components, vertical and horizontal. The actual current and voltage signals are converted to the stator voltage direction coordinate system. The control of current and voltage becomes more direct and simple. In the stator voltage direction coordinate system, the amplitude and phase of the current are directly controlled to achieve precise control of the motor torque and magnetic field. The operating status of the motor is monitored in real time by sensors, the feedback signal is compared with the expected value, and the output is adjusted by the control algorithm to ensure that the motor always operates in the best working state. Finally, the Simulink module is used to build a doubly-fed asynchronous wind turbine model, and the motor, transformer, load and other modules in the power system library are connected according to the mathematical model to perform simulation verification. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 8496.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 2.66 MB | Adobe PDF | View/Open |
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