【作者】 申科；

【导师】 王建赜；

【作者基本信息】 哈尔滨工业大学 ， 电气工程， 2009， 硕士

【摘要】 随着信息技术的飞速发展,基于计算机、微处理器控制的各种用电设备被大量使用,这些新型电力负荷对电能质量的要求不断提高,电压跌落、瞬时断电等暂态电能质量问题已成为电力用户共同关心的问题。动态电压恢复器(Dynamic Voltage Restorer,DVR)装置是一种能够保护关键负荷免受供电端电压跌落、骤升等扰动的新型电力电子设备。级联型多电平逆变器结构简单,技术成熟,易于封装和模块化,已广泛应用在有源滤波、无功补偿等电能质量控制领域。因此,本文针对级联型多电平拓扑结构的动态电压恢复器进行了研究。快速、准确地检测出系统电压跌落的特征量是动态电压恢复器运行的前提条件。本文针对三相系统中基于瞬时无功功率理论的dq0变换方法,引入并设计了数字低通滤波器,在保持检测精度的前提下提高了系统的响应速度。考虑到αβ变换法由于数据的非实时性给检测结果带来的延时和扰动,提出了一种基于拓展矢量的单相电压跌落快速检测算法,该算法以αβ变换检测方法为基础,利用三角函数的正交性,可快速检测出电压幅值和相角的跳变。在动态电压恢复器控制策略的研究方面,分析了前馈控制、负载电压瞬时值反馈控制和电压电流双环反馈控制三种控制方法在稳态和动态性能指标以及稳定性上的优缺点,提出一种基于比例谐振控制器的新型多环反馈控制策略,与传统的比例积分(PI)控制相比,含有谐振控制器的反馈控制能获得更高的稳态精度。直流侧电压平衡是级联型动态电压恢复器的关键问题。针对级联型多电平无串联注入变压器拓扑结构的DVR,详细定量分析了其稳态工作特性。分析表明调节补偿电压相角,可以实现稳定直流电容电压。提出了通过调节DVR注入电压相角实现快速补偿电网电压跌落的同时保持直流侧电压稳定的控制策略。该控制策略在最小能量补偿模式的基础上,将PI控制引入到注入电压生成方法中,DVR从电网吸收或发出有功功率,储能电容随之充电或放电以使电压恢复到额定值。为了减小直流电容间的电压偏差,进而提出引入内环PI控制器解决级联型多电平逆变器工作时H桥逆变单元之间的电容电压均衡问题的方法。最后,本文设计了一台基于DSP数字化控制的单相级联型五电平动态电压恢复器实验样机,进行了主电路方案设计、控制实验板的搭建及程序设计。实验结果表明,本文所设计的动态电压恢复器补偿效果良好,可以满足小功率场合电压跌落补偿的要求,为进一步研究奠定了的理论和实践基础。更多还原

【Abstract】 With the rapid development of information technology, variety of computer-based and microprocessor-controlled power equipments have been used extensively. The new power load demands for continually improving of power quality, the transient power quality problem, such as voltage sags and Instantaneous interruptions of power supply, have become important issues of common concern of power user. A dynamic voltage restorer (DVR) is a power-electronic converter-based device that has been designed to protect critical loads from supply-side voltage sags and other disturbances. Cascade multilevel inverter structure is simple and mature in technological conditions, and easy to modularize and package, which has been widely applied in the field of active filter and reactive power compensation. So, the cascaded multilevel topology based dynamic voltage restorer is researched in this paper.For the operation of dynamic voltage restorer, fast and exact detection of voltage sag characteristics is very important. According to three-phase system instantaneous reactive power theory based dq0 transformation method, in this paper, a digital low pass filter is introduced and designed, which can improve response speed while maintain detection precision. Considering the delay and disturbance of detection results caused by non-real-time data ofαβtransformation method, a single-phase voltage sag detection algorithm based on expanded vector is presented. The improved method mainly originates fromαβtransformation method, can rapid detect the jump of voltage amplitude and phase angle, utilizing the orthogonality of trigonometric functions.In this paper, the steady-state, dynamic performance and stability of control strategy of DVR, including forward-feed control, instantaneous voltage feed-back control, voltage and current double closed-Loop control are analyzed. A novel multi-loop control method with resonant controller for DVR is introduced. Compared to traditional proportional integral (PI) control, the feedback control with resonant controller achieves high steady-state precision.DC voltage balance is the key issues of cascaded dynamic voltage restorer. For the cascaded multilevel transformerless topology based dynamic voltage restorer, of which steady state characteristics were analyzed quantitatively. Analyses show that DC capacitor voltage can be changed by adjusting the injected voltage phase angle. It is deduced feasible method that compensating by adjusting the injected voltage phase angle to achieve DC voltage stable control, under the premise of rapid compensation of system voltage sags. A novel injected voltage generating method with PI controller is introduced based on the minimum energy compensation model. The DVR can absorb or deliver active power to maintain the DC capacitor voltage at its reference value. In order to minimize the DC capacitor voltage deviation, PI closed-loop control is used to solve the problem of cascade inverter power balance. The correctness of theoretical analysis and the feasibility of the proposed design scheme are verified by simulation results.At last, this paper designs a single-phase five-level DVR experimental prototype with DSP-based digital control system. The scheme designs of main circuit, implementation of experimental control board are presented in this paper. The results show that DVR designed by this paper has a good compensation effect, which gives important theoretical and practical foundation for further research.更多还原