【作者】 赵丹；

【导师】 赵国生；

【作者基本信息】 郑州大学 ， 电力系统及其自动化， 2017， 硕士

【摘要】 谐波抑制在提升电能质量以及保障供用电设备的安全稳定运行等方面有着关键性作用;无功功率不仅对于供电侧来说十分重要,而且在负载的正常运行过程中扮演着不可替代的角色。伴随功率半导体开关器件的飞速发展,大量的非线性负载涌现在电力系统中,由此带来的谐波污染和无功功率问题愈发严峻。在上述背景下,一方面可以对谐波进行抑制,另一方面又可以补偿无功功率的有源电力滤波器则受到了国内外学者们的青睐。有源电力滤波器的主电路拓扑结构是系统中最基础的部分,本文将由此出发,分别介绍各主电路的结构特征以及基本原理。简单叙述了有源电力滤波器常用的谐波检测方法,比较其各自的优劣,其中着重突出本文所用到的基于瞬时无功功率的改进的ip-iq法。针对传统电流跟踪控制策略对谐波信号跟踪动态效果差、控制目标单一的问题,在三相四线制不对称负载系统中,提出了一种多目标优化模型预测电流控制策略。首先建立四桥臂有源电力滤波器基于αβγ坐标系的离散化数学模型,以此来实现自然解耦控制;其次对预测电流进行两步预测,实现对数字处理延时效应的补偿,设置电流跟踪偏差和开关频率为目标函数,量化控制目标,预先评估各开关状态的控制效果,根据评估结果决定变流器的开关状态,省去了PWM调制环节;再次讨论了采样频率以及加权系数这两个系统变量的取值对开关频率和电流畸变率所造成的影响;文章的最后,为了验证所提方法的有效性,在Matlab/Simulink仿真环境下进行实验,结果证实所提策略谐波电流跟踪性能良好。更多还原

【Abstract】 Harmonic suppression plays an key role in improving power quality and ensuring the safe and stable operation of power supply equipment.Reactive power is not only very important to the power supply system,but also has an indelible value for the normal operation of the load.With the rapid development of power semiconductor switching devices,numerous nonlinear loads emerge in the power system,the resulting harmonic pollution and reactive power problems become increasingly serious.In such a premise,the active power filter,which can suppress the harmonics and compensate the reactive power,is favored by the domestic and foreign scholars.The main circuit topology of active power filter is the most basic part of the system.From this point of view,this paper discusses the structural features and basic principles of each main circuit.The harmonic detection methods commonly used in active power filters are briefly introduced,and their advantages and disadvantages are compared.The improved ip-iq method based on instantaneous reactive power is highlighted in this paper.Aiming at the problem of poor tracking dynamic performance of harmonic signal and single control target in the traditional current control strategy,a predictive control strategy of multi-objective optimization model is proposed in the three-phase four-wire asymmetric load system.Firstly,the discrete mathematical model of four-arm active power filter(FAPF)based on the αβγ coordinate system is established to realize natural decoupling control.Secondly,two-step prediction of the predicted current is performed to compensate for the delay effect.Set the current tracking bias and switching frequency as the objective function,quantify the control objectives and pre-assess the control state of the switch effect.Thirdly,the switching state of the converter is determined by the evaluation results and the PWM modulation is omitted.The influence of sampling frequency and weight coefficient on switching frequency and current distortion is discussed.Finally,the simulation results show that the proposed strategy harmonic current has good tracking performance and can effectively reduce the switching frequency.更多还原