高低压整流桥式励磁控制方案及仿真分析

研究了一种适合于三峡特大型机组的高低压整流桥式励磁方案,该方案既能保证强励时励磁电压具有很高的顶值倍数,又能解决额定运行时因触发角过大所带来的问题.具体研究了适合高低压整流桥的2种工作模式:高低压桥同时承担正常励磁任务的工作模式;低压桥单独承担正常励磁任务的工作模式.针对三峡机组,对2种工作模式及传统励磁模式下的励磁电压换相次数及谐波畸变率进行了分析,得出三峡机组采用高低压整流桥式励磁方案时,应优先选择第2种工作模式.进一步的暂态过程仿真表明,高低压桥自并励系统能较好地满足三峡机组的实际需要.

High and Low Voltage Bridge Rectifiers Based Excitation Control Scheme and Its Simulation Analysis

An excitation system based on high and low voltage bridge rectifiers is studied for huge-scale generators in Three Gorges Hydropower Station, which can guarantee high ceiling voltage and solve the problems caused by large firing angle under rated load. Two operation modes are investigated in detail, i.e. the high and low voltage bridges burdening normal excitation and only the low voltage bridge burdening normal excitation. The commutation times and the high order harmonic contents of the excitation voltage are analyzed and the transient processes are simulated for Three Gorges' huge-scale generators. The results show that this kind of exaction scheme can satisfy the practical requirement.