基于虚拟阻抗的微网谐波抑制方法研究

发布时间：2018-06-08 14:58

本文选题：微网 + 谐波抑制　；参考：《浙江工业大学》2015年硕士论文

【摘要】：微网由于能够协调大电网与分布式发电系统之间的矛盾,日渐受到人们的关注。然而,微网中非线性负荷的接入、微电源的并网、大量电力电子设备的应用以及高电压等级电网谐波的渗透会造成微网系统输出的电压或电流发生畸变,导致微网中存在大量的谐波分量。这些谐波的存在将会给微网带来很多危害,甚至危及微网的安全稳定性。因而,如何抑制谐波,保证微网的电能质量是目前微网研究的重点问题之一。为解决微网谐波问题,提出基于虚拟阻抗的微网谐波抑制方法,并利用免疫粒子群算法优化微网滤波器参数,达到抑制微网谐波的目的,降低电压谐波率。主要研究内容如下:1.针对基于传统下垂控制的光伏微网系统,对光伏微源、逆变器接口、功率控制、下垂控制以及电压电流双环控制进行建模,并对系统中产生的谐波问题进行分析。2.针对光伏微网系统中的谐波问题,提出基于免疫粒子群算法的微网滤波器参数优化方法。首先,建立对应的目标函数和适应度函数,并给出LC滤波器参数的约束条件。其次,在粒子群算法中加入免疫算法,利用免疫算法的自我调节功能,避免粒子群算法的早熟收敛问题,进而提高算法的全局搜索能力。同时,利用Matlab实现免疫粒子群算法的编程,并采用该算法调用微网仿真系统,得到滤波器最优参数。最后,与经验值法得到的仿真结果进行对比,验证所提方法在抑制微网谐波方面的有效性与优越性。3.在滤波器参数优化的基础上,进一步提出基于虚拟阻抗的微网谐波抑制方法。首先,在传统控制中的基波功率下垂控制基础上,通过功率控制器计算出谐波无功功率,利用谐波无功功率与谐波指令电压之间的下垂控制关系,设计出谐波无功功率下垂控制模块。其次,根据虚拟阻抗的基本原理,设计出虚拟谐波阻抗模块,实现对相关谐波电流和虚拟谐波阻抗的求解,得到虚拟谐波电压。将虚拟谐波阻抗模块与谐波无功功率下垂控制模块相结合,得到谐波补偿电压。最后,利用Simulink工具在微网孤岛与并网状态下实现所提方法。案例分析表明,该方法能够有效地抑制微网谐波,降低电压畸变率,提高电能质量。
[Abstract]:The micro network is attracting more and more attention because it can coordinate the contradiction between the large power grid and the distributed generation system. However, the access of the nonlinear load, the grid of the micro power supply, the application of a large number of power electronic devices and the penetration of the harmonic in the high voltage grade power grid will cause the distortion of the voltage or current of the output of the microgrid system. There are a lot of harmonic components in the micronetwork. The existence of these harmonics will bring a lot of harm to the micronet, even endangers the safety and stability of the micronet. Therefore, how to restrain the harmonic and ensure the power quality of the micronet is one of the key problems in the research of micronet. In order to solve the problem of micro network harmonic, the harmonic suppression of micronet based on the virtual impedance is put forward. And using the immune particle swarm optimization (PSO) algorithm to optimize the parameters of the microgrid filter to suppress the micronet harmonics and reduce the voltage harmonics. The main contents are as follows: 1. for the photovoltaic microgrid system based on the traditional droop control, the photovoltaic micro source, inverter interface, power control, droop control and voltage and current double loop control are built. The harmonic problem in the system is analyzed and the harmonic problem in the photovoltaic micronetwork system is analyzed by.2.. The method of optimizing the parameters of the microgrid filter based on the immune particle swarm optimization is proposed. First, the corresponding objective function and fitness function are established, and the constraints of the LC filter parameters are given. Secondly, the particle swarm optimization is added to the particle swarm optimization algorithm. The immune algorithm, using the self-regulation function of the immune algorithm, avoids the premature convergence problem of particle swarm optimization, and then improves the global searching ability of the algorithm. At the same time, the programming of the immune particle swarm optimization algorithm is realized by Matlab, and the algorithm is used to call the micronet simulation system, and the optimal parameters of the filter are obtained. Finally, the imitation of the empirical value method is obtained. Real results are compared to verify the effectiveness and superiority of the proposed method in restraining the harmonics of micronet..3. based on the optimization of the filter parameters, the method of harmonic suppression based on the virtual impedance is further proposed. First, the harmonic reactive power is calculated by the power controller on the basis of the base wave power drooping control in the traditional control. Rate, using the droop control relationship between harmonic reactive power and harmonic instruction voltage, the harmonic reactive power droop control module is designed. Secondly, based on the basic principle of virtual impedance, a virtual harmonic impedance module is designed to achieve the solution of the related harmonic current and virtual harmonic impedance, and the virtual harmonic voltage is obtained. The anti module and the harmonic reactive power droop control module are combined to obtain the harmonic compensation voltage. Finally, the Simulink tool is used to implement the proposed method under the state of micronetwork isolated island and grid connected. The case analysis shows that this method can effectively suppress the micronet harmonics, reduce the voltage distortion and improve the power quality.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM727

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