影响并联有源滤波器补偿性能的关键技术及其实验研究

发布时间：2018-09-07 21:00

【摘要】：最近几年,电力电子技术蓬勃发展,电力电子装置得到广泛应用,然而在应用过程中产生的谐波与无功对电网造成的诸多危害日渐增大。SAPF(Shunt Active Power Filter,并联有源电力滤波器)为一种主流装置,主要实现谐波抑制和无功补偿功能,在电能质量领域占据重要地位。如今在国内,SAPF产品还未大规模推向市场,其补偿性能有待提高,因此对影响其补偿性能的关键技术的研究已成为研究的最前沿的课题之一。对补偿电流进行检测是在研发SAPF过程中采用的一项重要技术手段。检测的快速性和精准性,对SAPF的补偿性能起到重要的影响。本文分析了传统FBD(F.Buchholze M.Dpendbrock,巴布迪)谐波检测法,然后在此基础上提出改进型的FBD法,此种方法首先是通过基波正序电压正余弦信号取代PLL(Phase Locked Loop,锁相环)模块,并且用基波正序电压代替电源电压参与等效电导的计算来减少检测误差,然后用均值滤波器取代LPF(Low Pass Filter,低通滤波器)来减小延时。仿真结果表明此方法可以实时和精确地对系统中各种电流分量进行检测。SAPF主电路参数是影响补偿性能的决定性因素之一,研究了三个重要参数(直流侧电压、交流侧电感和直流侧电容容量)的计算公式。首先分析了换相过程对三相桥式整流器带阻感性负载的交流侧谐波电流的影响,推导出考虑换相重叠角的负载电流的表达式;其次在此基础上推导了直流侧电压设定值的计算公式;然后由在参考电流变化剧烈时和缓慢时,分别应该满足补偿电流的变化速率要不小于参考电流变化速率和补偿电流在一个开关周期内的波动要小于工程上的最大允许值,从而推导出电感的计算公式;最后利用负载瞬时有功功率的交流分量是负载与SAPF之间交换的缓冲功率,推导出直流侧电容容量的计算公式。仿真结果证明了理论推导的正确性和合理性。为了提高SAPF的控制性能,本文研究了两大类控制方法:电流控制和直接功率控制。首先通过基于不定频滞环的SVPWM(Space Vector Pulse Width Modulation,电压空间矢量脉宽调制)与传统滞环控制比较,得出前者在补偿效果、开关频率和直流电压利用率方面具有一定优势。然后提出了基于pq理论的DPC(Direct Power Control,直接功率控制)策略,首先把检测出的谐波和无功功率作为参考功率信号,再将其检测值与滤波器输出的谐波和无功功率的偏差送入两个相应的滞环比较器中,根据滞环比较器的输出以及电源电压矢量位置角,通过查开关表得到所需的桥臂输出电压矢量对应的开关状态。仿真结果表明了采用这种控制策略设计出的SAPF具有良好的谐波补偿效果。最后提出了基于电源功率和虚拟磁链的DPC方法,该算法直接采用电源功率对SAPF进行控制,从而省略了负载谐波和无功的检测及计算环节,又由于通过估计虚拟磁链来计算有功与无功功率,因此可省略电源侧电压传感器。仿真结果表明了与传统的DPC方法相比较,该方法系统结构简单,能有效减少传感器的数量,电源电流的畸变较小和具有更好的瞬时功率控制特性。最后,对软件系统设计进行了研究,在前期工作的基础上改进了硬件平台,并且在该实验系统上对本文研究的关键技术进行了综合实验。通过两组对比实验,对实验结果进行了分析,表明了本文研究工作的正确性和可行性。
[Abstract]:In recent years, power electronics technology has been booming and power electronics devices have been widely used. However, the harmonics and reactive power generated in the application process have caused increasing harm to the power grid. Nowadays, SAPF products have not been put into the market on a large scale in China, and its compensation performance needs to be improved. Therefore, the research on the key technologies affecting its compensation performance has become one of the most advanced topics. The detection of compensation current is an important technology used in the development of SAPF. This paper analyzes the traditional FBD (F. Buchholze M. Dpendbrock) harmonic detection method, and then proposes an improved FBD method based on it. This method first replaces PLL (Phase Locked Loop) by fundamental sinusoidal voltage cosine signal. In order to reduce the detection error, the fundamental positive sequence voltage is used instead of the source voltage to participate in the calculation of the equivalent conductance, and then the mean filter is used to replace the LPF (Low Pass Filter) to reduce the delay. Number is one of the decisive factors affecting the compensation performance. The calculation formulas of three important parameters (DC voltage, AC inductance and DC capacitance) are studied. Secondly, the formulas for calculating the DC voltage setting value are deduced. Then, when the reference current changes sharply and slowly, the variation rate of compensation current should be satisfied, whether it is less than the reference current variation rate or the compensation current fluctuation in a switching period should be less than the maximum allowable in engineering. Finally, by using the AC component of the instantaneous active power of the load as the buffer power exchanged between the load and SAPF, the calculation formula of the capacitance of the DC side is deduced. Firstly, by comparing SVPWM (Space Vector Pulse Width Modulation) based on indefinite frequency hysteresis with traditional hysteresis control, it is concluded that the former has certain advantages in compensation effect, switching frequency and utilization ratio of DC voltage. The DCP (Direct Power Control) strategy first takes the detected harmonic and reactive power as the reference power signal, and then feeds the deviation between the detected value and the output harmonic and reactive power of the filter into two corresponding hysteresis comparators. The simulation results show that the SAPF designed by this control strategy has good harmonic compensation effect. Finally, a DSP method based on power supply and virtual flux is proposed, which directly uses power supply to control the SAPF and thus omits. The detection and calculation of load harmonics and reactive power are realized, and the active and reactive power can be calculated by estimating the virtual flux, so the voltage sensor on the power side can be omitted. The simulation results show that the proposed method is simple in structure and can effectively reduce the number of sensors, the distortion of power current is small and the power supply voltage sensor can be omitted. Finally, the software system design is studied, and the hardware platform is improved on the basis of the previous work, and the key technologies studied in this paper are comprehensively experimented on the experimental system. The experimental results are analyzed by two groups of comparative experiments, which show the research work in this paper. Correctness and feasibility.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM761;TN713.8

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