LCL型多逆变器谐振抑制方法研究

发布时间：2018-11-14 19:56

【摘要】：随着太阳能光伏并网发电规模的日益扩大,并网逆变器并联的台数就会越大,LCL型光伏并网逆变器产生的谐振问题就会越加明显,对电网电能质量的不良影响也就会加重,所以谐振问题在光伏并网系统中不能忽视。解决逆变器谐振问题成为了光伏发电并网系统中的一个重要环节,对光伏建设和电网电能质量有着重要意义。针对LCL型的多逆变器谐振问题,本文分别对L型、LC型、LCL型滤波器的数学模型进行了分析,并且对L型与LCL型滤波器,LC型与LCL型滤波器进行了对比研究,总结出了它们之间的优缺点,应用仿真软件Matlab得到各自的Bode图,通过对比Bode图,发现LCL滤波器对高次谐波的滤除效果最佳。LCL滤波器对谐波能很好地滤除,但是由于LCL滤波器自身结构原因产生了谐振,又展开了逆变器的结构、LCL滤波器的参数、阻尼方法对谐振的研究,并应用仿真软件Matlab得到了相应的Bode图,同时也对无源阻尼、双闭环有源阻尼进行了相应的仿真,通过仿真结果得知,这些方法对谐振具有一定的抑制,但随着并联台数的增加和系统功率的增加,又存在一定的局限性。为此,本文从逆变器的本身特性出发,提出了一种在光伏并网逆变器控制算法中引入一个电导反馈回路方法,在LCL滤波器中的电容两端并联一个电导。先从常规单机光伏并网逆变器出发,再到光伏并网多逆变器分析,由浅到深,逐步分析;改进控制算法,由单机到多机,应用仿真软件Matlab得到改进算法前后的Bode图,通过对比Bode图,发现改进算法对谐振抑制效果明显。
[Abstract]:With the increasing scale of solar photovoltaic grid-connected generation, the number of parallel inverters will be larger, and the resonance problem caused by LCL photovoltaic grid-connected inverter will become more obvious, and the negative impact on power quality will be aggravated. So the resonance problem can not be ignored in photovoltaic grid-connected system. To solve the problem of inverter resonance has become an important link in the grid-connected system of photovoltaic generation, which is of great significance to the construction of photovoltaic system and the power quality of power grid. In this paper, the mathematical models of L type, LC type and LCL type filter are analyzed, and the comparison between L type and LCL filter, LC type and LCL type filter is carried out. The advantages and disadvantages between them are summarized, and their Bode diagrams are obtained by using the simulation software Matlab. By comparing the Bode diagram, it is found that the LCL filter has the best effect on the filtering of high order harmonics, and the LCL filter can filter the harmonics well. However, because of the resonance of LCL filter, the structure of inverter, the parameters of LCL filter and the damping method are studied. The corresponding Bode diagram is obtained by using the simulation software Matlab, and the passive damping is also obtained. The simulation results show that these methods can suppress the resonance to some extent, but with the increase of the number of parallel stations and the increase of system power, there are some limitations. Therefore, based on the characteristics of the inverter, this paper presents a method of introducing a conductance feedback loop into the control algorithm of the grid-connected photovoltaic inverter, in which the two ends of the capacitor in the LCL filter are connected in parallel. From the conventional single-machine photovoltaic grid-connected inverter, then to the photovoltaic grid-connected multi-inverter analysis, from shallow to deep, step by step analysis; The improved control algorithm, from single computer to multi-computer, the Bode diagram before and after the improved algorithm is obtained by using the simulation software Matlab. By comparing the Bode diagram, it is found that the improved algorithm has obvious effect on the resonance suppression.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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