基于虚拟阻抗的微电网下垂控制策略及谐波抑制方法研究

发布时间：2019-05-16 06:36

【摘要】：随着社会经济的不断发展、电力需求的持续增长,微电网在新能源的利用方面可以充分发挥优势,其发展受到了越来越多的关注和重视。在微电网中,由于电力电子变换器和非线性负荷的存在,谐波问题对微电网的影响日益显著,也会严重影响电网的电能质量。本文以建立基于虚拟阻抗的微电网下垂控制策略和谐波抑制方法为目标,研究基于SOGI虚拟阻抗的微电网下垂控制策略。首先,分析了微电源的功率传输特性,建立了微电源电压电流环控制器、功率计算单元和下垂控制器模型。通过频域法对微电源电压电流环控制模型的传递函数进行分析,并采用极点配置法对电压电流环控制器的参数进行了设计。其次,在传统的下垂控制策略的基础上引入虚拟阻抗控制环,建立了基于二阶广义积分(Second Order Generalized Integrator, SOGI)虚拟阻抗的下垂控制策略。采用频域法对比分析了虚拟阻抗控制环对系统输出特性的影响,并根据逆变器控制系统的闭环传递函数,进行虚拟阻抗下垂控制模型的稳定性分析。通过微电网运行仿真,对基于虚拟阻抗的下垂控制方法的有效性进行了验证。最后,分析了含虚拟阻抗的微电网谐波抑制方法,在MATLAB/Simulink中建立了微电网谐波抑制仿真算例,对微电网孤网和并网运行时的谐波抑制效果进行了研究,并分析了虚拟阻抗值对微电网谐波抑制效果的影响。本论文建立的基于SOGI虚拟阻抗的下垂控制策略可以使系统稳定运行,实现负载变化时功率自动分配。基于虚拟阻抗的微电网谐波抑制方法,可以有效地抑制微电网谐波,改善电能质量,对谐波抑制具有一定的意义。
[Abstract]:With the continuous development of social economy and the continuous growth of power demand, microgrid can give full play to its advantages in the utilization of new energy, and its development has received more and more attention and attention. In microgrid, due to the existence of power electronic converter and nonlinear load, harmonic problem has more and more significant influence on microgrid, and it will also seriously affect the power quality of power grid. In this paper, the sag control strategy of microgrid based on virtual impedance and harmonic suppression method are established, and the drooping control strategy of microgrid based on SOGI virtual impedance is studied. Firstly, the power transmission characteristics of micro power supply are analyzed, and the voltage and current loop controller, power calculation unit and droop controller model of micro power supply are established. The transfer function of the voltage and current loop control model of the micro power supply is analyzed by the frequency domain method, and the parameters of the voltage and current loop controller are designed by using the pole assignment method. Secondly, on the basis of the traditional droop control strategy, the virtual impedance control loop is introduced, and the sag control strategy based on the second order generalized integral (Second Order Generalized Integrator, SOGI) virtual impedance is established. The influence of virtual impedance control loop on the output characteristics of the system is compared and analyzed by frequency domain method, and the stability analysis of virtual impedance drooping control model is carried out according to the closed-loop transfer function of inverter control system. The effectiveness of the droop control method based on virtual impedance is verified by microgrid operation simulation. Finally, the harmonic suppression method of microgrid with virtual impedance is analyzed, and a simulation example of microgrid harmonic suppression is established in MATLAB/Simulink, and the effect of harmonic suppression in isolated and grid-connected operation of microgrid is studied. The influence of virtual impedance value on harmonic suppression effect of microgrid is analyzed. In this paper, the sag control strategy based on SOGI virtual impedance can make the system run stably and realize the automatic power allocation when the load changes. The method of microgrid harmonic suppression based on virtual impedance can effectively suppress microgrid harmonics and improve power quality, which is of great significance to harmonic suppression.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM727

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