并联型APF及其直流侧电压平衡控制方法研究

发布时间：2018-03-29 02:30

本文选题：直流侧母线电压　切入点：中点电位　出处：《西安科技大学》2017年硕士论文

【摘要】：有源电力滤波器能够实时的补偿谐波和无功,得到了广泛的应用。然而APF正常工作时,由于自身存在损耗或当其切换工作状况时,都会使直流侧与交流侧之间存在功率的交换,从而引起直流侧母线电压出现波动;另外,对于三电平有源电力滤波器而言,会有电流流入或者流出直流侧串联电容的中点,对上下电容不停的充放电,致使中点电位不平衡。直流侧母线电压的波动和中点电位的失衡将导致输出电压发生畸变,直接影响APF的补偿精度和系统效率。因此,保持直流侧母线电压的稳定和中点电位的平衡对于APF具有重要的意义。首先,分析了T型三电平APF直流侧电压波动的原因、中点电位的失衡原因,详细介绍了APF主电路的工作原理,并对其换流过程进行分析。研究了APF的直流侧母线电压和中点电位平衡常用的PI控制方法和载波脉宽调制策略。其次,针对T型三电平APF直流侧母线电压波动和中点电位平衡的问题,使用PI控制方法对直流侧母线电压稳定控制并采用在调制参考电压上叠加零序电压的载波脉宽调制策略对中点电位平衡进行控制。然后,根据系统控制要求,在仿真软件MATLAB/SIMULINK环境中搭建APF系统模型,对直流侧电压控制进行仿真分析。最后,在APF直流侧电压控制的理论分析和仿真基础上,搭建了三相三线制的T型三电平有源电力滤波器控制系统实验平台,并采用所述的方法对直流侧母线电压和中点电位进行平衡控制。在平台上进行实验,实验结果证明文中所采用的控制方法可以有效控制直流侧电压的平衡。
[Abstract]:Active power filter (APF) can compensate harmonic and reactive power in real time, and it has been widely used. However, when APF works normally, because of its own loss or when it is switched, there will be power exchange between DC side and AC side. In addition, for a three-level active power filter, there will be currents flowing in or out of the neutral point of the DC side of the series capacitance to charge and discharge the upper and lower capacitors. The fluctuation of DC bus voltage and the imbalance of midpoint potential will lead to output voltage distortion, which will directly affect the compensation accuracy and system efficiency of APF. It is important for APF to maintain the stability of DC bus voltage and the balance of neutral point potential. Firstly, the causes of DC side voltage fluctuation and the imbalance of neutral point potential of T type three-level APF are analyzed. The working principle of APF main circuit is introduced in detail, and its commutation process is analyzed. The Pi control method and carrier pulse width modulation strategy for DC side bus voltage and midpoint potential balance of APF are studied. Aiming at the problems of voltage fluctuation and neutral-point potential balance in T-type three-level APF DC side bus, The voltage stability of DC bus is controlled by Pi control method, and the midpoint potential balance is controlled by the carrier pulse width modulation strategy with zero sequence voltage superimposed on the modulation reference voltage. Then, according to the system control requirements, The APF system model is built in the simulation software MATLAB/SIMULINK environment, and the DC side voltage control is simulated and analyzed. Finally, on the basis of theoretical analysis and simulation of APF DC side voltage control, An experimental platform of three-phase three-level three-level active power filter control system is built, and the DC bus voltage and neutral point potential are balanced by the method mentioned above. The experiment is carried out on the platform. The experimental results show that the proposed control method can effectively control the balance of DC side voltage.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761

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