变速恒频系统并网一体化设计的研究

发布时间：2018-05-27 18:53

本文选题：变速恒频系统 + 谐波分析　；参考：《湖南大学》2016年硕士论文

【摘要】：伴随着工业现代化进程的加快和近代科学技术的飞速发展,变速恒频(VSCF)系统越来越多的在实际生活中使用。在目前的新能源发电领域,如风力发电、余热发电等,大多采用背靠背双PWM变流器对能量进行传输。随着电力电子器件的大量使用,将会给整个发电系统和电网带来大量的谐波。目前国内外对于网侧的谐波抑制大多采用L或者LCL无源滤波器实现。但是由于电机本体的工艺和死区效应,电机定子中同样带有大量的谐波,这些谐波轻则影响电机发电效率和发热,重则导致电机损坏。对于电机定子谐波的抑制成为变速恒频系统应用中的一个难题。首先,本文以永磁直驱式风力发电系统为例,对变速恒频系统两种重要的拓扑结构进行了介绍,针对谐波的问题再介绍了几种常用的谐波抑制策略。为了方便后面的分析,本文介绍了一种常用的背靠背PWM变流器控制策略。并通过MATLAB/simulink的仿真对所介绍的控制策略的有效性进行了验证。其次,从电机的本体和变流器控制的角度入手,本文对谐波产生的原因进行了深入的分析。由于电机的工艺问题,在电机定子中会产生一些无规律性的齿槽转矩,从而带了无规律的谐波。同时变流器的死区效应又会带来大量有规律性的谐波,而因为开关管管压降的原因使得这些谐波加重,更大程度的影响变速恒频系统正常运行。这些谐波可以通过傅里叶分解成一系列的奇数次谐波,同时又由于电机定子为星型连接,抵消了三的倍数次谐波,得到了发电机定子的各次谐波含量。然后通过MATLAB/simulink的仿真对所提出的结论进行了验证。针对这些谐波,网侧可以采用LCL滤波电路并网。对于机侧变流器,本文先通过传统的比例积分准谐振控制器控制,但是通过系统的伯德图发现,传统的比例积分准谐振控制器在永磁同步发电机的谐波抑制中的带宽过小且稳定性差。为了解决传统的比例积分准谐振控制器的这些问题,本文提出了一种改进式的比例积分准谐振控制器,通过伯德图可以看出系统带宽和稳定性大幅度提高,提升了比例积分准谐振控制器的实际应用价值。最后通过MATLAB/simulink的仿真对所提出的改进式的比例积分准谐振控制器进行了验证。最后,先是对实验平台的硬件的选型和作用进行了详细的介绍,网侧采用LCL滤波电路进行滤波并网；然后通过软件流程图对实验平台的软件流程进行了详细的分析；再通过所搭建的实验平台机侧变流器对本文所提的控制策略进行了试验运行,得到运行后的实验数据。
[Abstract]:With the acceleration of industrial modernization and the rapid development of modern science and technology, VSCFs are more and more used in real life. At present, in the field of new energy generation, such as wind power generation, waste heat generation and so on, most of the energy is transmitted by back-to-back dual PWM converter. With the extensive use of power electronic devices, it will bring a lot of harmonics to the whole power generation system and power grid. At present, most of harmonic suppression at home and abroad is realized by L or LCL passive filter. However, due to the process and dead-time effect of the motor, there are also a large number of harmonics in the stator of the motor. The light of these harmonics will affect the generation efficiency and heat of the motor, and lead to the damage of the motor. The harmonic suppression of motor stator becomes a difficult problem in the application of variable speed constant frequency system. Firstly, this paper introduces two kinds of important topology of variable speed constant frequency system by taking permanent magnet direct drive wind power system as an example, and introduces several common harmonic suppression strategies for harmonic problems. In order to facilitate the later analysis, this paper introduces a control strategy of back-to-back PWM converter. The effectiveness of the proposed control strategy is verified by MATLAB/simulink simulation. Secondly, from the angle of motor body and converter control, the cause of harmonic generation is analyzed in this paper. Due to the technical problems of the motor, some irregular torque of the tooth slot will be produced in the stator of the motor, and thus there will be irregular harmonics. At the same time, the dead-time effect of the converter will bring a large number of regular harmonics, and because of the voltage drop of the switch tube, these harmonics will be aggravated, which will affect the normal operation of the variable speed constant frequency system to a greater extent. These harmonics can be decomposed into a series of odd harmonics by Fourier transform. At the same time, because the stator of the motor is star connected, the multiple harmonics of the generator stator are offset, and the harmonic content of the generator stator is obtained. Then the conclusion is verified by the simulation of MATLAB/simulink. In view of these harmonics, the LCL filter circuit can be used in the grid-connected network. For the machine side converter, the traditional proportional integral quasi-resonant controller is used to control the converter, but it is found by the Byrd diagram of the system. The traditional proportional integral quasi-resonant controller has a small bandwidth and poor stability in harmonic suppression of permanent magnet synchronous generator (PMSG). In order to solve these problems of the traditional proportional integral quasi-resonant controller, an improved proportional integral quasi-resonant controller is proposed in this paper. The practical application value of proportional integral quasi-resonant controller is improved. Finally, the improved proportional integral quasi-resonant controller is verified by MATLAB/simulink simulation. Finally, the hardware selection and function of the experimental platform are introduced in detail, the LCL filter circuit is used to filter the network side and the software flow chart is used to analyze the software flow chart of the experimental platform in detail. Then, the control strategy proposed in this paper is tested by the experimental platform, and the experimental data are obtained.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM46;TM61

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