Improved Passivity-Based Control Method of Grid-Connected PV Inverter in Weak Grids
Improved Passivity-Based Control Method of Grid-Connected PV Inverter in Weak Grids
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DOI：
10.23919/icems.2018.8549169
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
L. Guihua;Wang Wenxiu;Zhuo Xiaohui;Wang Wei
中科院分区：
文献类型：
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作者：
L. Guihua;Wang Wenxiu;Zhuo Xiaohui;Wang Wei
随着光伏（PV）普及率的不断提高，电网的运行环境变得越来越复杂。薄弱电网通常具有谐波含量高、电网阻抗大、电压波动大等电气特性。当光伏并网逆变器接入弱电网时，传统的控制方法表现出其局限性。针对光伏逆变器数学模型的非线性，采用基于无源控制（PBC）理论的算法对光伏逆变器进行控制，使逆变器在弱电网中具有更好的性能。本文首先基于能量法建立了逆变器的欧拉-拉格朗日（EL）数学模型，证明了逆变器系统的无源性。其次，应用无源性控制理论，通过引入阻尼，设计了逆变器系统的传统无源性控制器;然后提出了一种改进的基于准PR控制方法的无源性控制方法，即先将误差能量送入准PR控制器以改变系统的阻尼系数，然后将该系数送至传统的基于无源性的控制器以实现改进的基于无源性的控制方法。最后，通过实验比较两种方法，表明改进的无源性控制方法更适合于电压不稳定、阻抗较大的弱电网。实验结果表明，改进的无源性控制对电压波动具有较强的鲁棒性。
With the continuous increase in the penetration rate of photovoltaics (PV), the operating environment of the power grid becomes more and more complex. Weak grids usually present electrical characteristics like high harmonic content, high grid impedance and fluctuating voltage. When a grid-connected PV inverter is connected to weak grids, the traditional control method shows its limitation. In view of the nonlinearity of the mathematical model of the PV inverters, the algorithm derived from passive-based control (PBC) theory can be used to control the PV inverter, enabling the inverter to have better performance in weak grids. Firstly, this paper establishes the Euler-Lagrange (EL) mathematical model of the inverter based on energy method, and proves the passivity of the inverter system. Secondly, passivity-based control is applied to design the traditional passivity-based controller of the inverter system by injecting damping; then an improved passivity control method based on quasi-PR control method is proposed, namely, the error energy is first sent to the quasi- PR controller to change the damping coefficient of the system, then the coefficient is send to a conventional passivity-based controller to achieve the improved passivity-based control method. Finally, experimental comparison of the two methods show that the improved passivity-based control method is more suitable for weak grids with voltage instability and large impedance. The experimental results verify that the improved passivity-based control has strong robustness when the voltage fluctuates.