Alternating Current Excitation Control Of Asynchronized Synchronous Generator Based On Digital Signal Processor

With the development of power system and enhancement of transmission line voltage, the problem of power system's stability is more and more of standing out. The asynchronized synchronous generator (ASG)'s reactive power and active power can be adjusted independently by excitation control because of ASG's special multi-phase wounded winding rotor structure, which provides a novel approach for improving power system's stability and extending generator's operating range. The AC-DC-AC voltage source inverter (VSI) main circuit and TMS320LF2407 are selected to form high performance alternating current (AC) excitation system of ASG in this dissertation after detail schemes argumentation. The constitution, interface and control principle of main circuit, rectifier control module, inverter control module, generator's rotor speed and rotor position measuring module, information exchange module are discussed. Specially, the methods of implementing signals level match in multi-voltage system, synchronizing with PC in parameters measurement and measuring rotor speed and rotor position with high precision are explained in detail. The system software uses typical foreground/background model. The main program serves as background and interrupts' ISRs serve as foreground. System program responses all measuring, controlling, communicating and displaying tasks in time through switching between foreground and background and queuing tasks in terms of priority level. The concerted control strategy of rectifier and inverter is analyzed to keep high modulation degree of SPWM, which achieves quick response and high resolution of excitation voltage regulation. The approximate computation method is used in float point computation of system's control algorithms after comparing several methods in respect of running time and program space involved, which attains quick computation besides high precision and implements excitation voltage with low harmonic and high control precision of frequency. The information is exchanged between TMS320LF2407 and PC by CAN bus. The humancomputer interface is made up of LCD and touch screen. The system reached control goal by experimental verification and the experimental results showed the system could produce AC excitation voltage with low harmonic, quick adjusting speed, wide adjusting range and high control precision of frequency. At the same time, the paper put forward some proposed schemes to improve system performances.