Research Of Tidal Generation System Based On The Doubly-fed Motor

With the world's economic and social development, the energy demand of the world is increasing continuously, leading to the traditional fossil fuels are depleted, electricity shortage and environmental pollution are increasing. Developing the clean renewable tidal energy vigorously has extraordinary significance for easing energy shortages. Compared with the conventional tidal generation system, this VSCF system based on the doubly-fed motor has many advantages: the inverter of the system is smaller, lighter, and the cost is lower. Because of its efficiency and practicality, an increasing number of domestic and foreign scholars are beginning to pay attention to this system .Firstly, difference and relation between the general asynchronous and synchronous motor and doubly-fed machine with brushes are pointed out in this thesis . On this basis, the equivalent-circuit model of motor is established, issues about operational characteristics, power flow and static operation performance are qualitative analyzed. It concludes that the interrelations of control parameters under power control mode of doubly-fed machine are complicated, it is hard to achieve control objectives and tasks using scalar control strategy.Then, the VSCF operation principle of the doubly-fed machine is expatiated in the thesis. Based on the complex vector model, mathematical model in the synchronous rotary coordinate is established. The key techniques and realization methods of control mode, operational characteristic and system power flow are mainly studied. Some research is done in the Matlab/Simulink environment, the simulation results show that the decoupling control strategy for active and reactive power of the stator port can be achieved by adopting stator magnetic field oriented control strategy.In the end, the electrical excitation control system is designed for the motor in the thesis. TI's F2407DSP is used as the main control chip to design control circuit, main circuit and the drive circuits, some schematics of the key circuits are presented. Software of the dual-loop SVPWM control system for the doubly-fed machine has also been designed, some flowcharts of the main program, interrupt program and functions subprogram are presented in thesis too.