本科毕业论文_变速恒频风电机组交流励磁调节装置设计.doc

毕 业 设 计 设计题目：变速恒频风电机组交流励磁调节装置设计 变速恒频风电机组交流励磁装置设计 摘 要 目前，风力发电是我国政府正在大力发展的清洁能源，但风力发电有它自身的特点，就是风速是变化不定的。要想得到人们想要的合格电能，就要对风电机发出的电进行变换，或对风电机本身进行改进。但是，前者电力电子变换装置所需容量较大，电压和功率因数调节比较困难，近年电力电子技术的发展使对风电机本身的改进成为可能。 励磁装置的功能是实现风电机组的变速恒频运行，即发电机转子的转速是可变的，而发电机输出电压的频率是恒定的。励磁装置采用IGBT组成三相桥式逆变电路，由它来给绕线式异步发电机提供励磁电流。电机的转速通过测速发电机实时监测。转速信号输入S7-200的模拟量输入模块，经计算从PLC输出脉冲串，再经过驱动放大，控制IGBT的开通与关断，使逆变电路输出符合期望的PWM波形，即符合转子三相合成旋转磁场旋转速度为同步转速的三相交流电。根据运行状况，给风电机的励磁电流可以是直流也可以是交流。在最大风速时，可以保证同步转速。风速减小时，通过给转子绕组提供交流励磁，使风电机输出电压能保持50Hz。这样就实现了风力发电机的变速恒频运行。 关键词：风力发电 变速恒频 交流励磁 IGBT PLC The Design of AC excitation device of Variable speed and constant frequency wind power Abstract Currently, wind power is clean energy vigorously developing in government of china，but wind power has its own characteristics, the wind speed is fluctuated. To get qualified power people want，the electricity will be transformed or improvement of the wind turbine itself. However, the former is larger capacity requirements for power electronic conversion device，voltage and power factor is difficult to adjust. However, due to the development of power electronics technology in recent years，the wind turbine of improvements is possible. The features of excitation device is to achieve running of variable speed and constant frequency of the wind turbine. Variable speed and constant frequency , the rotor speed of the wind turbine is variable, while the frequency of the voltage of the generator is a constant. Therefore, to design a device different from the previous exchange excitation device. AC excitation device is a three-phase bridge inverter circuit, by it to provide excitation asynchronous generator. According to operating conditions, the excitation current to the motor can be DC can also be exchange. the synchronous speed can be guaranteed, when the maximum wind speed is maximum.Wind speed is reduced, by providing AC excitation to the rotor winding, the output voltage can maintain 50Hz.The speed of motor is maintain