Abstract

As the world increasingly turns to renewable energy sources, the integration of solar photovoltaic (PV) systems into the grid has emerged as a pivotal solution. Effective control methods are paramount to harnessing the full potential of these grid-connected PV systems. While existing control methods have laid a foundation, there persists a compelling need for innovative approaches capable of surpassing the limitations of conventional methods. This paper introduces a novel nonlinear control approach utilizing an enhanced Lyapunov function for a single-phase PV/grid electric power system. High-performance operation of the solar PV system, interfacing with a grid-connected single-stage inverter, is achieved through the control of maximum PV voltage using predictive voltage control for MPPT. The enhanced Lyapunov function maintains PV voltage stability at the dc-bus by treating the difference between PV voltage and its reference as a controlled state error. Notably, this approach ensures the stability of the closed-loop PV system even under varying solar irradiances. To achieve full active power injection into the grid with high quality, the proposed enhanced Lyapunov function is augmented by integrating an LCL filter with virtual resistance as an active damping circuit for grid current feedback control. This integration introduces an opposing current to the grid-side inductance current. This compensation mechanism corrects the q-axis grid current using the dq-SRF mathematical model of the global PV/grid system. The LCL parameters and virtual resistance design methods are provided. The effectiveness of the enhanced Lyapunov function is demonstrated through simulations using MATLAB/Simulink software. The results showcase outstanding performance when compared to conventional Lyapunov function and sliding mode control strategies in achieving key objectives, including zero state errors, global stability, and the generation of a sinusoidal grid current signal with low total harmonic distortion and the unit power factor at the point of common coupling.

中文翻译：

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单相光伏/并网电力系统的增强李亚普诺夫函数和有源阻尼预测电压控制性能与稳定性分析

摘要

随着世界越来越多地转向可再生能源，将太阳能光伏（PV）系统并入电网已成为关键的解决方案。有效的控制方法对于充分发挥这些并网光伏系统的潜力至关重要。虽然现有的控制方法已经奠定了基础，但仍然迫切需要能够超越传统方法限制的创新方法。本文介绍了一种针对单相光伏/电网电力系统利用增强型李亚普诺夫函数的新型非线性控制方法。通过使用 MPPT 预测电压控制来控制最大光伏电压，可实现与并网单级逆变器连接的太阳能光伏系统的高性能运行。增强型李亚普诺夫函数将 PV 电压与其参考电压之间的差异视为受控状态误差，从而保持直流母线上的 PV 电压稳定性。值得注意的是，即使在不同的太阳辐照度下，这种方法也能确保闭环光伏系统的稳定性。为了实现高质量的完全有功功率注入电网，通过集成具有虚拟电阻的 LCL 滤波器作为用于电网电流反馈控制的有源阻尼电路来增强所提出的增强型 Lyapunov 函数。这种集成引入了与电网侧电感电流相反的电流。该补偿机制使用全球光伏/电网系统的 dq-SRF 数学模型来校正q轴电网电流。提供了LCL参数和虚拟电阻设计方法。通过使用 MATLAB/Simulink 软件进行仿真，证明了增强型 Lyapunov 函数的有效性。与传统的李亚普诺夫函数和滑模控制策略相比，结果展示了在实现关键目标方面的出色性能，包括零状态误差、全局稳定性以及生成具有低总谐波失真和单位功率因数的正弦电网电流信号。公共耦合点。