动态电压恢复器DVR控制技术的研究

发布时间：2018-12-30 12:02

【摘要】：随着工业化程度的日益提高,电力负荷急剧增加,特别是冲击性、非线性负荷容量的不断增长,使得电网出现各种各样的电能质量问题。根据各国学者和电力部门的统计和分析,在电力系统的各种电能质量问题中,电压暂降是发生概率最高的电能质量问题之一。动态电压恢复器是近年来出现的一种可以补偿电压的电力电子装置,串联于电源与敏感负荷之间,具有良好的动态特性。当发生电压暂降时,它能在极短的时间内对电压暂降进行有效补偿,还能抑制电源电压中的谐波、闪变等干扰,是抑制动态电压干扰的有效装置。本文在对动态电压恢复器的基本结构及工作原理的分析和研究的基础上,对电压检测方法、补偿控制策略以及控制方法这三个方面的控制技术进行了研究。在检测方面,本文介绍了传统的电压检测方法,选取了对电压相位进行归零的电压检测方法,进行了理论推导以及仿真分析,验证了其有效性。在补偿方面,本文对各种传统的补偿策略进行了研究,着重研究了最小能量补偿法的基本原理,引入了补偿功率圆的概念来阐述补偿水平的高低与电压暂降间的关系。利用电力系统仿真软件PSCAD来搭建模型,构建了动态电压恢复器各组成部分的模型,实施仿真分析获得了系统在遭受单相接地故障而导致电压暂降问题时的波形,也得到了电压暂降得到补偿后的补偿效果波形。在控制方面,本文对传统的控制方法进行了详细的归纳和分类,研究了各传统控制方法。选用了闭环控制方法,加上前馈校正以及在前向通道上加了积分控制环节,成为改进的前馈控制方法。对比研究了改进的前馈控制方法的传递函数和开环控制的传递函数,分别求出Bode图和单位阶跃响应图进行比较分析。最后对改进的前馈控制方法进行了仿真,仿真结果验证了改进前馈控制方法的可行性。
[Abstract]:With the increasing of industrialization, the power load increases sharply, especially the impact and nonlinear load capacity, which makes the power network appear a variety of power quality problems. According to the statistics and analysis of scholars and power departments in various countries, voltage sag is one of the most likely power quality problems in power system. Dynamic voltage restorer is a kind of power electronic device which can compensate the voltage in recent years. It has good dynamic characteristics in series between power supply and sensitive load. When voltage sag occurs, it can compensate voltage sag effectively in a very short time. It can also suppress harmonic, flicker and other interference in power supply voltage. It is an effective device to suppress dynamic voltage interference. Based on the analysis and study of the basic structure and working principle of the dynamic voltage restorer, the control techniques of voltage detection, compensation control strategy and control method are studied in this paper. In the aspect of detection, this paper introduces the traditional voltage detection method, selects the voltage detection method to zero the voltage phase, carries on the theoretical derivation and the simulation analysis, verifies its validity. In the aspect of compensation, various traditional compensation strategies are studied, the basic principle of minimum energy compensation method is emphatically studied, and the concept of compensation power circle is introduced to explain the relationship between compensation level and voltage sag. The power system simulation software PSCAD is used to build the model, and the models of each component of the dynamic voltage restorer are constructed, and the waveform of the voltage sag caused by the single-phase grounding fault is obtained by the simulation analysis. The compensation effect waveform after voltage sag is compensated is also obtained. In the aspect of control, the traditional control methods are summarized and classified in detail, and the traditional control methods are studied. The closed-loop control method, plus feedforward correction and integral control on the forward channel are selected as the improved feedforward control method. The transfer function of the improved feedforward control method and the transfer function of the open-loop control are compared and analyzed. The Bode diagram and the unit step response diagram are calculated and analyzed respectively. Finally, the improved feedforward control method is simulated, and the simulation results verify the feasibility of the improved feedforward control method.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761.12

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