The Research On The Digital Excitation System Of The Diesel Generator

Diesel generator is a small and medium-sized independent power generation equipment, at present, the excitation controller of the small and medium-sized generator still is analog excitation controller, analog excitation controller hasn't the capacity in the realization of high-precision and highly adaptive excitation controller, the digital excitation controller has high precision, fast response and the strong adaptability in control algorithm, so the digital excitation controller has the trend of replacing the analog excitation controller in recent years.First of all, the paper introduced the status of the diesel generator sets, the development trends of the diesel generator sets and the development of the excitation system, introduced the composition of the diesel generator sets briefly, studied the small and medium-sized program of the synchronous generator excitation, comparaed and analyed the advantages and disadvantages of a variety of exciting programs, described why the brushless excitation was selected as the excitation program of the diesel generator.After analyed the role and the performance indicators of the diesel generator's excitation controller, the paper designed the excitation power main circuit of the diesel generator exhaustivly, including: the switching excitation power unit based on IGBT, start exciting circuit, de-excitation circuit, bridge rectifier protection circuit, IGBT drive and protection circuit and so on, moreover the paper gave the parameters and the basis of selection of the diodes and the excitation transformer.The paper used a DSP chip named TMS320F2812 as the control chip of the excitation controller. When designing the hardware, the plenty peripherals of the chip named TMS320F2812 were fully used. Moreover, the frequency measurement circuit with high reliability, the multichannel AC/DC signal synchronized sampling circuit, the switch input and output circuit with optical coupling, the man-machine interface circuit and so on were conformed to the integration. When designing the software, the program followed with the programming ideas of structured, modularized, top-dowm and refined step by step. The frequency measurement module with high readability, the data sampling and calculating module, the PWM pulse generator module and the excitation limit and protection module were designed. All the modules were embedded seamlessly in the macrosoftware frame. Finally, the paper gave the mathematical model of the excitation system, and proposed the fuzzy PID control algorithm, made a comparation in simulation with the excitation system whose control algorithm is the conventional PID control algorithm, comparaed and analyed both terminal voltage waveform in the condition of start excitating and when the voltage was changed, the results show that the excitation system useing the fuzzy PID control algorithm in the aspect of improving the dynamic performance is better than the the excitation system useing the conventional PID control algorithm.