双馈风力发电机励磁系统技术的研究

发布时间：2019-04-26 04:21

【摘要】：随着新能源的日益盛行,风能的应用吸引了越来越多国家的关注和研究,而在众多应用于风力发电的发电技术中,双馈风力发电技术则以其独一无二的优势而备受人们重视。但是,风能具有随机性和不稳定性,会引起双馈风力发电定子侧电网有功功率不稳定,这影响了风能的广泛利用。为解决在风力发电中的这一弊端,课题将储能装置引入风力发电系统中,这样可以在一定范围内很好的调整定子侧电网的有功平衡。在传统的储能装置与风力发电系统的结合方式中,储能装置位于双馈风力发电机的定子侧,可是在这种结合方式中,储能装置与定子侧电网相连,仍会造成电网的不稳定性。课题设计了一种新型的结合方式,将储能装置与双馈风力发电机的转子侧励磁系统相结合。当风能变化时,发电机定子侧按电网要求提供有功功率,而多余(或不足)的转差功率,则由转子侧的储能装置吸收(或提供),而无需与电网交换能量,从而使发电机系统能够更好的、更稳定的为电网提供输出。储能装置通过充放电电路与直流母线进行连接,因而充放电电路作为一个重要环节会直接影响直流母线两端电压的稳定性,进一步就会影响到双馈风力发电机的转子侧励磁电压的稳定性。针对课题研究应用的超级电容器的特有的一些性质,课题设计了充放电电路主电路,以及在充电和放电模式下的控制策略,并利用Mat]ab软件对储能系统进行了仿真。在利用充放电电路实现了逆变器直流母线电压稳定的前提下,课题基于SVPWM技术对励磁系统的低频逆变控制策略进行了设计研究,并对其进行了仿真分析,结果表明三相SVPWM逆变器具有很好的低频电压输出特性。论文设计了交流励磁系统的拓扑结构,研究了交流励磁系统中网侧和转子侧变换器的数学模型,根据网侧变换器在双馈电机励磁系统中的作用,利用空间电压矢量控制技术,设计了电压、电流双闭环的控制策略;依据交流励磁系统对转子侧变换器的要求,设计了一种输出电压幅值、频率分别可调的转子侧变换器控制策略,通过仿真验证,网侧变换器能够在保持功率因数为1的条件下输出稳定的直流电压,且转子侧变换器可以根据双馈发电机的运行需求,输出幅值、频率和相位可调的交流励磁电流。以此为基础,把转子侧变换器与双馈风力发电机结合,运用电压电流双闭环的控制策略,实现了双馈风力发电机变速恒频运行。为了实现并网控制,根据双馈风力发电机的运行特点,将双闭环控制技术应用在双馈发电机的并网控制上,研究了一种以网侧电压参数为依据,进而对转子励磁电流的幅值、频率和相位进行调节的柔性并网控制策略,将并网过程中的冲击电流控制在合理的范围内,最终实现了双馈风力发电机的柔性并网。
[Abstract]:With the increasing popularity of new energy, the application of wind energy has attracted more and more countries' attention and research. Among the many technologies used in wind power generation, doubly-fed wind power generation technology has attracted more and more attention for its unique advantages. However, the randomness and instability of wind energy will cause the instability of active power of doubly-fed wind power generation stator-side grid, which affects the wide use of wind energy. In order to solve this drawback in wind power generation, the energy storage device is introduced into the wind power generation system, so that the active power balance of stator-side power grid can be well adjusted within a certain range. In the traditional combination of energy storage device and wind power generation system, the energy storage device is located at the stator side of the doubly-fed wind generator. However, in this combination mode, the energy storage device is connected to the stator-side power grid, which will still cause the instability of the power network. A new combination method is designed, which combines the energy storage device with the rotor side excitation system of doubly-fed wind generator. When the wind energy changes, the stator side of the generator provides the active power required by the power grid, and the excess (or insufficient) slip power is absorbed (or provided) by the energy storage device on the rotor side without the need to exchange energy with the power grid. So that the generator system can be better, more stable for the power grid to provide output. Energy storage device is connected with DC bus through charge-discharge circuit, so charge-discharge circuit as an important link will directly affect the stability of voltage at both ends of DC bus. Furthermore, the stability of the rotor side excitation voltage of doubly-fed wind generator will be affected. Aiming at the special properties of supercapacitor, the main circuit of charge and discharge circuit and the control strategy in charge and discharge mode are designed, and the energy storage system is simulated by using Mat] ab software. On the premise that the DC bus voltage of the inverter can be stabilized by charge-discharge circuit, the low-frequency inverter control strategy of excitation system based on SVPWM technology is designed and studied, and the simulation analysis is carried out. The results show that the three-phase SVPWM inverter has good low-frequency voltage output characteristics. In this paper, the topology of AC excitation system is designed, and the mathematical models of grid-side and rotor-side converters in AC excitation system are studied. According to the function of network-side converter in excitation system of doubly-fed machine, the space voltage vector control technology is used. The double closed loop control strategy of voltage and current is designed. According to the requirements of AC excitation system for rotor-side converter, a control strategy of rotor-side converter with adjustable output voltage amplitude and frequency is designed, which is verified by simulation. The grid-side converter can output stable DC voltage under the condition that the power factor is 1, and the rotor-side converter can output AC excitation current with adjustable amplitude, frequency and phase according to the operation requirement of doubly-fed generator. Based on this, the rotor-side converter is combined with the doubly-fed wind generator, and the voltage-current double closed-loop control strategy is used to realize the variable speed constant frequency operation of the doubly-fed wind generator. In order to realize grid-connected control, according to the operation characteristics of doubly-fed wind generator, the double-closed-loop control technology is applied to the grid-connected control of doubly-fed generator, and the amplitude of excitation current of rotor is studied on the basis of grid-side voltage parameters. The flexible grid-connected control strategy with frequency and phase adjustment can control the impulse current in the grid-connected process within a reasonable range and finally realize the flexible grid-connection of doubly-fed wind generators.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM315

【参考文献】