分布式光伏集群谐振抑制方法研究

发布时间：2018-04-15 15:41

本文选题：多机逆变器并联系统 + 谐振特性　；参考：《华北电力大学》2017年硕士论文

【摘要】：近年来,我国分布式光伏呈现出连片开发,集群并网的特点。光伏集群系统中存在大量的LCL滤波器,与配网阻抗构成复杂的高阶电网络,使光伏集群系统存在多个的固有谐振点。当分布式发电集群入网系统电压电流谐波频率与系统固有谐振点频率相匹配时,将发生谐振。目前已有的分布式光伏并网工程中,已出现了多起逆变器并联运行产生谐振导致并网失败的案例。因此,研究弱电网条件下,多机逆变器并联系统的谐振特性及其抑制策略对实现新能源系统安全稳定运行具有重要的意义。本文以多机逆变器并联系统为研究对象,分析系统的谐振特性。首先研究并联LCL系统的多输入多输出传递函数,并在此基础上,建立了多机逆变器并联系统的传递函数,利用此模型分析多机逆变器之间的交互影响,得到并联逆变器数量、电网阻抗和系统组成比例对系统谐振特性的影响。针对LCL型逆变器的并网谐振问题,开展逆变器自身的无源阻尼和有源阻尼谐振抑制方法的研究。对无源阻尼方法和有源阻尼方法的机理进行研究,并分析电网阻抗对无源阻尼以及有源阻尼方法的影响。最后,提出一种基于陷波控制的逆变器自身谐振抑制方法。针对光伏集群全局谐振问题,本文提出集中式的谐振抑制方法。根据谐振抑制的不同原理,分别提出无源型投切阻抗式谐振抑制技术和有源型虚拟阻尼式谐振抑制方法,这两种方法都为在并网点处并联一台谐振抑制装置实现对分布式光伏集群的谐振抑制。最后,通过仿真验证两种方法的正确性。
[Abstract]:In recent years, distributed photovoltaic in China presents the characteristics of continuous development and cluster grid-connected.There are a large number of LCL filters in photovoltaic cluster system, which form a complex high-order electric network with impedance of distribution network, which makes photovoltaic cluster system have multiple inherent resonance points.When the harmonic frequency of voltage and current is matched with the frequency of the inherent resonance point of the system, the resonance will occur.In the existing distributed photovoltaic grid-connected projects, there have been many cases of inverter parallel operation resulting in resonance resulting in grid connection failure.Therefore, it is of great significance to study the resonance characteristics and its suppression strategy of multi-machine inverter parallel system under the condition of weak current network to realize the safe and stable operation of the new energy system.In this paper, the resonant characteristics of multi-machine inverter parallel system are analyzed.Firstly, the transfer function of parallel LCL system is studied. Based on this, the transfer function of parallel inverter is established. The interaction between inverter and inverter is analyzed by using this model, and the number of parallel inverters is obtained.The influence of power system impedance and system composition ratio on the resonance characteristics of the system.Aiming at the grid-connected resonant problem of LCL inverter, the passive damping and active damping resonant suppression methods of the inverter are studied.Finally, a notch control based resonant suppression method is proposed.Aiming at the global resonance problem of photovoltaic cluster, a centralized resonant suppression method is proposed in this paper.According to different principles of resonant suppression, passive switching impedance resonant suppression and active virtual damping resonant suppression are proposed, respectively.Both of these two methods are designed to realize the resonance suppression of distributed photovoltaic cluster by paralleling a resonance suppressor at the parallel node.Finally, the correctness of the two methods is verified by simulation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM615

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