【作者】 彭劲杰；

【导师】 樊晓平；

【作者基本信息】 中南大学 ， 计算机应用技术， 2013， 博士

【摘要】 电能是国民经济和人民生活的命脉,随着电力电子技术的飞速发展,各种大功率开关器件得到了广泛应用,非线性负载大量增加。它们造成电网的谐波污染和电能损失；同时冲击性负载及无功补偿不足常引起电网电压跌落和闪变,并导致线路损耗增加。这些问题影响了企业的正常生产和人民的日常生活,给我国电力系统带来了繁重的无功控制和谐波治理问题。有源电力滤波器(active power filter, APF)对电网无功控制和谐波治理等的作用已经得到公认。但是目前APF还存在很多问题有待于进一步研究和完善,因此对APF的研究仍然是电力电子应用技术中的一个重大课题。例如,如何在非理想工况下保证APF的有效运行；当APF的逆变器出现故障,如何能使APF快速正常运行等工程性质问题。本文从有源电力滤波器的容错运行方面,提出了容错并联型APF的结构,深入研究了容错并联型APF的相关理论和方法。研究内容涵盖了容错并联型APF的工作机理分析、数学建模、指令电流提取算法、控制算法、以及脉宽调制算法等方面,形成了较为完善的容错并联型APF的基本研究方法和技术方案,研究重点及取得的成果主要体现在以下几个方面：(1)根据逆变器故障的特点,主要提出了一种容错并联型APF结构。首先给出了逆变器可能发生的故障类型。分析了容错并联型APF结构原理,给出了故障情况下的几种运行模式和运行原理。(2)分析了三相四开关逆变器的输出电压和输出电流的规律,并分析了三相四开关逆变器直流侧电压波动时产生的影响,即使三相四开关逆变器输出的电压空间矢量产生偏置。将该结构和无故障时的三相六开关结构进行了比较,为这种结构的参数设计提供了理论依据。(3)提出了容错并联型有源电力滤波器的指令电流获取方法,在负载不平衡情况下该方法提取负载电流中的正序基波有功电流。将该方法进行了仿真验证,表明其在多种不利情况下能较好的获得指令电流。(4)结合容错并联型有源电力滤波器的结构特点,说明了直流侧电容电压的控制目标,针对性地提出了直流侧电容总电压稳定方法和直流侧电流检测方法,提出了一套完整的控制策略。仿真结果表明,采用上述控制方法的容错并联型有源电力滤波器能有效抑制负载谐波电流,在逆变器故障时,能使APF正常工作,并且电容总电压保持恒定、两电容电压均衡。(5)提出了容错并联型APF的SVPWM调制算法。首先给出了三相四开关逆变器的传统SVPWM算法,该算法涉及大量无理数和三角函数运算,将耗费大量运算时间,并且不可避免地引入计算误差。另一方面由于电压空间矢量与αβ标系存在角度差,扇区判断方法复杂。本文改进了三相四开关逆变器的SVPWM算法,利用新的坐标变换矩阵,使电压空间矢量的作用时间的计算和扇区的判断大大简化,无需无理数和三角函数运算。但是该算法是在直流侧电压平衡的状态下的算法。(6)提出了在直流侧电压不平衡的状态下的SVPWM算法。针对直流侧电压不平衡时电压空间矢量发生偏置,提出了合成零电压空间矢量的方法。并且给出了电压空间矢量作用时间和扇区判断的方法。将该方法应用到容错并联型APF中,直流侧电压不平衡的现象得到极大改善。本文以配电网电能质量控制、提高有源电力滤波器运行安全性能为背景,提出了容错并联型APF。工程应用的容错方案设计思路可推广到其它电能质量控制电力电子系统的设计和应用中,为推进电力电子系统的实用化进程提供有益的参考和借鉴。图66幅,表8个,参考文献108篇更多还原

【Abstract】 Abstract:Electrical energy plays an important role in the economic development and people’s lives. With the rapid development of power electrical technologies and widely used high power switch devices, non-linear loads in the grid are widely increased, which causes harmonic pollution and energy losses. Meanwhile, voltage fluctuation and voltage flicker caused by the impulsive load and reactive power variation have greatly disturbed the industrial production and people’s lives. It also makes the electrical system have problems such as heavy reactive power compensation and harmonic suppression. Active power filter has good well-known performance on reactive power compensation and harmonic suppression. But there are many problems for APF to be researched and improved. It is still an important task for APF on the field of power electrical applying technology. For example, it is under non-ideal operation condition how to keep APF running effectively, even when the inverter in APF has fault.This paper proposes the structure of fault tolerant parallel active power filter, named APF operating with fault tolerant, to improve the safe performance for APF. The relative theories and methods of fault tolerant APF are researched. The working mechanism, mathematical model, instructing current extracting method, control method, pulse modulating method and so on are researched in the paper. The basic researching method and technical proposal of fault tolerant APF are formed. The emphasis and achievement of the paper mainly manifests in the following aspects.(1) According to the characteristic of inverter fault, a structure of fault tolerant parallel APF is proposed. The possible fault types of inverter are given first. The structure of fault tolerant parallel APF is analyzed. Several operating models and corresponding primaries under fault condition are discussed.(2) The regular pattern outputting voltages and currents of three-phase four-switch inverter is analyzed. The influence caused by the DC-linked voltage fluctuation of three-phase four-switch inverter is also analyzed. That is the offset of the output voltage space vector of three-phase four-switch inverter. Comparing the structure with the three-phase six-switch structure without fault, the theory evidence of parameter design is provided.(3) The instructing current extracting method for fault tolerant parallel APF is proposed. The positive order fundamental active current can be obtained by the method even under unbalance load condition. The method is test and verified with simulation. The instructing current can be gotten under different bad condition.(4) Combining the structure characteristic of fault tolerant parallel APF, the controlling aim of DC-link capacitor voltage is illustrated. The method to stabilize the DC-link total voltage and the method to detect the DC-link current are proposed. The corresponding controlling strategy is put forward. The simulation is done. Simulating results show that the fault tolerant parallel APF can suppress the harmonic currents effectively. APF can work normally when the inverter is fault. The DC-link total voltage is kept stable and two capacitor voltages are kept balance.(5) The modulating method of SVPWM for fault tolerant APF is proposed. The traditional SVPWM method is given first, which needs a great deal of irrational number and trigonometric function operations. A lot of operating time is cost. The computing error is unavoidably is led into at the same time. On the other hand, due to the angle difference between the voltage space vector and the αβ coordinate system, it is complicate to judge sector. An improved SVPWM method for three-phase four-switch inverter is proposed in the paper. Using new coordinate transformation matrix, the computation of space voltage vector working time and the judgement of sector are simplified, which need not the irrational number and trigonometric function operations. However, the method works under the condition of DC-link voltage balance.(6) A SVPWM method with DC-link voltage unbalance is proposed. A method composing zero voltage space vectors is put forward with the DC-link voltage unbalance. The methods of computing the working time of voltage space vector and the judgment of sector are provided. The DC-link voltage unbalance is greatly restrained by the proposed SVPWM method.According to the background of power quality control and the improvement of operating safety for APF, the fault tolerant parallel APF is proposed in the paper. The fault schematic design for engineering application can be popularized to the other design and application in the field of power electrical systems. It is beneficial to push on the practical application for the power electrical systems.更多还原