不平衡和畸变电网下三相锁相环研究

发布时间：2019-05-30 04:23

【摘要】：环境污染和能源危机问题愈加凸显,人类在寻求可持续发展的探索中愈加关注太阳能、风能等可再生能源的开发利用。分布式发电系统作为新型的电能转换系统具有小型模块化、分散性的特点,很好的弥补了可再生能源能量分布不集中的缺陷。分布式发电系统在满足自给自足的情况下,将多余电能并网传输给公共电网,达到补给公共电网的作用。因此如何稳定高效的将分布式发电系统接入电网成为各国学者研究的热点,这一过程中快速精准感知公共电网相位、频率和幅值信息,以便及时准确的调整控制策略是至关重要的。锁相环是获取电压信息的有效方法,基于同步旋转坐标的锁相环是较成熟的解决方案,但在电网电压不平衡或者发生畸变时,环路中存在较多的二次谐波,严重降低锁相效果。本文就此作为切入点,对不平衡和畸变电网下三相锁相环技术进行了详细的研究。首先,本文探讨了提取电压正序基级分量的方法。详细分析电网存在扰动时电压矢量关系,介绍成熟的正交信号发生器技术,深入研究基于二阶广义积分解耦法、双同步坐标系解耦法的传递函数,总结各正负序解耦方法对正负序分量滤波的等效性。其次,在对现有的正负序解耦与锁相方法总结基础上,将瞬时功率理论引入锁相环研究,利用该理论对谐波处理的优势,在环路中构造出参考电流,提出一种新的基于参考电流的锁相环方法,并利用变参数PI控制器进行优化。在基于参考电流锁相环的研究基础上,设计电网不平衡下锁相环电路框图,分析对比各锁相环方法优缺点。最后,通过Matlab仿真平台模拟不平衡和畸变电网情况,将以上各方法进行仿真实验,得到稳态响应和动态响应,对结果进行分析讨论,证实本文提出的锁相环方法在电网故障下能准确检测电压相位和频率信息,对各方法检测效果进行综合比对,结果表明该方法具有一定优势。
[Abstract]:The problems of environmental pollution and energy crisis are becoming more and more prominent. In the exploration of sustainable development, human beings pay more attention to the development and utilization of renewable energy such as solar energy and wind energy. As a new type of power conversion system, distributed power generation system has the characteristics of small modularization and dispersion, which makes up for the lack of centralized energy distribution of renewable energy. Under the condition of self-sufficient, the distributed power generation system connects the excess power to the public power grid, and achieves the function of replenishing the public power grid. Therefore, how to connect the distributed power generation system to the power grid stably and efficiently has become the focus of scholars all over the world. In this process, the phase, frequency and amplitude information of the public power grid are quickly and accurately sensed. In order to adjust the control strategy timely and accurately is very important. Phase-locked loop is an effective method to obtain voltage information. Phase-locked loop based on synchronous rotating coordinates is a mature solution, but when the voltage of power grid is unbalanced or distorted, there are more second harmonics in the loop, which seriously reduces the phase-locked effect. In this paper, the three-phase-locked loop (PLL) technology under unbalanced and distorted power grid is studied in detail. Firstly, the method of extracting positive sequence base level components of voltage is discussed in this paper. The relationship of voltage vector when there is disturbance in power grid is analyzed in detail, the mature orthogonal signal generator technology is introduced, and the transfer function based on second-order generalized integral decomposition coupling method and double synchronous coordinate system decoupling method is deeply studied. The equivalence of each positive and negative order decoupling method for positive and negative sequence component filtering is summarized. Secondly, on the basis of summing up the existing positive and negative sequence decoupling and phase-locked methods, the instantaneous power theory is introduced into the study of phase-locked loop, and the reference current is constructed in the loop by using the advantages of this theory for harmonic processing. A new phase-locked loop method based on reference current is proposed and optimized by variable parameter PI controller. Based on the research of reference current phase-locked loop, the circuit diagram of phase-locked loop under unbalanced power grid is designed, and the advantages and disadvantages of each phase-locked loop method are analyzed and compared. Finally, through the Matlab simulation platform to simulate the imbalance and distortion of the power grid, the above methods are simulated, the steady-state response and dynamic response are obtained, and the results are analyzed and discussed. It is proved that the phase-locked loop method proposed in this paper can accurately detect voltage phase and frequency information under power grid fault, and the detection results of each method are compared synthetically. The results show that this method has certain advantages.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761

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