三相双向变流器无锁相环控制策略

发布时间：2018-05-10 10:07

  本文选题：锁相环 + 无锁相环　； 参考：《南京航空航天大学》2014年硕士论文

【摘要】：随着能源危机和环境污染的加重,风能、太阳能等新能源的开发和利用成为时代的焦点,三相双向变流器作为分布式发电系统中与电网相接的设备起着至关重要的作用。锁相环技术常用于控制系统中检测电网电压的相位和频率,但由于电网电压存在不平衡和畸变的问题,锁相角的计算会产生一定的误差。因此,研究三相变流器的无锁相环控制策略成为电力电子领域的一大热点。本文首先介绍了锁相环技术和无锁相环技术的研究现状及发展趋势,同时分析了不同电网电压情况下的常规锁相环的锁相误差。本文设计并完成了一台18kVA全数字控制的三相双升压/双降压变流器,针对常规锁相环容易受电网电压影响的这一问题,提出两类变流器的无锁相环控制策略:直接功率控制和直接电流控制,并建立数学模型验证其可行性。仿真与实验证明,与锁相环控制策略相比,无锁相环控制策略能够快速精确地从不平衡以及含有畸变的电网电压中分离出基波正序分量,提高系统在电网电压不理想条件下的运行能力。之后本文从锁相效果、适用范围、算法复杂性以及动态响应速度等角度对提出的无锁相环控制策略进行对比。为了解决电网角频率出现偏差时对基于二阶广义积分器的无锁相环控制策略的影响,提出了一种基于二阶广义积分器的锁频环控制策略,建立了其在频域上的数学模型,并分析了其动态响应性能。仿真和实验表明,该锁频环只需采用负增益系数的积分器即可实现频率锁定,适用于变流器的不平衡控制、谐波抑制以及频率突变的场合。最后,采用常规锁相环控制和锁频环控制策略在实际电网情况下进行变流器双向运行实验对比,证明了本文提出的新型锁频环的优越性。
[Abstract]:With the aggravation of energy crisis and environmental pollution, the development and utilization of new energy, such as wind energy and solar energy, has become the focus of the times. Three-phase bidirectional converter plays an important role as the equipment connected with the power grid in the distributed generation system. Phase-locked loop (PLL) technology is often used to detect the phase and frequency of power grid voltage in control system. However, due to the imbalance and distortion of power grid voltage, the calculation of phase-locked angle will cause some errors. Therefore, the study of phase-free loop control strategy of three-phase converter has become a hot spot in power electronics field. In this paper, the research status and development trend of PLL technology and PLL technology are introduced, and the phase locked error of conventional PLL under different grid voltage is analyzed. In this paper, a three-phase double boost / double step-down converter with 18kVA full digital control is designed and completed, aiming at the problem that the conventional PLL is vulnerable to the influence of power grid voltage. This paper presents two kinds of phase-locked loop control strategies for converters: direct power control and direct current control, and establishes mathematical models to verify their feasibility. The simulation and experiments show that compared with the PLL control strategy, the PLL control strategy can quickly and accurately separate the fundamental positive sequence component from the unbalanced and distorted grid voltage. Improve the system operation ability under the condition of the imperfect voltage of the power network. Then this paper compares the proposed control strategy from the aspects of phase locking effect, application range, algorithm complexity and dynamic response speed. In order to solve the influence of angle frequency deviation on the phase locked loop control strategy based on second order generalized integrator, a frequency locked loop control strategy based on second order generalized integrator is proposed, and its mathematical model in frequency domain is established. The dynamic response performance is analyzed. Simulation and experiments show that the frequency locking can be realized only by using an integrator with negative gain coefficient, which is suitable for unbalanced control of converter, harmonic suppression and frequency abrupt change. Finally, the conventional phase-locked loop control and frequency-locked loop control strategy are used to compare the bidirectional operation of the converter in the actual power network, which proves the superiority of the novel frequency locked loop proposed in this paper.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46
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本文编号：1868881