This paper presents the design and experimental validation of disturbance observer (DO)-based control for grid-tied photovoltaic (PV) inverters fed by a dc-dc boost converter considering unbalanced grid voltages. The control scheme uses multiples controllers that are developed based on employing DO technique along with a feedback-linearizing (FBL) control. The main controller is designed to regulate the active and reactive powers injected into the grid via controlling the grid-tied inverter. Under unbalanced grid voltages, the active and reactive power is composed of a dc component as well as an ac component that oscillates at twice the grid frequency. Therefore, the unknown perturbation, representing the mismatch between the nominal and actual system, can be treated as a sum of a constant offset and a sinusoidal disturbance. To ensure accurate control of the active/reactive power, a DO is designed to estimate the unknown perturbation, which is then canceled by a FBL control. By considering the control input limitation in the observer synthesis, an antiwindup compensator arises naturally in the control law, which attenuates the effect of the windup phenomenon during control saturation. Moreover, a simplified representation of the DO is proposed to facilitate real-time implementation. The proposed approach for the power control can be used in both balanced and unbalanced systems since it can reject constant and sinusoidal disturbances. Experimental tests were performed to investigate the ability of the proposed control scheme to achieve good transient and steady-state performances.

中文翻译：

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电网电压不平衡下双级并网光伏系统基于扰动观测器的控制


本文介绍了基于扰动观测器 (DO) 的并网光伏 (PV) 逆变器控制的设计和实验验证，该并网光伏逆变器由 DC-DC 升压转换器供电，考虑了不平衡电网电压。该控制方案使用基于 DO 技术和反馈线性化 (FBL) 控制而开发的多个控制器。主控制器旨在通过控制并网逆变器来调节注入电网的有功功率和无功功率。在不平衡电网电压下，有功功率和无功功率由直流分量和以两倍电网频率振荡的交流分量组成。因此，代表标称系统和实际系统之间不匹配的未知扰动可以被​​视为恒定偏移和正弦扰动之和。为了确保有功/无功功率的精确控制，DO 被设计来估计未知的扰动，然后通过 FBL 控制来消除。通过考虑观测器综合中的控制输入限制，控制律中自然会出现抗饱和补偿器，从而减弱控制饱和期间饱和现象的影响。此外，提出了 DO 的简化表示以促进实时实现。所提出的功率控制方法可用于平衡和不平衡系统，因为它可以抑制恒定和正弦扰动。进行了实验测试，以研究所提出的控制方案实现良好瞬态和稳态性能的能力。