Advanced Decoupling Techniques for Grid-Connected Inverters With Multiple Inputs

• Published in: IEEE access 2021, Vol.9, p.148409-148420
• Main Authors: Song, Guanhong, Cao, Bo, Chang, Liuchen, Shao, Riming
• Format: Article
• Language: English
• Subjects: Algorithms; Capacitor banks; Capacitors; Control algorithms; Control theory; DC-AC power converters; Decoupling method; Distributed generation; Electric potential; Energy sources; Estimation; feedforward systems; Fluctuations; Inverters; Nonlinear control; nonlinear control systems; Observers; Transient analysis; Voltage; Voltage control
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2021.3124614

The parallel connection of multiple distributed energy resources with a common DC-link structure is typically used in grid-connected applications which enables flexible operation maximizing power production of the inverter system under various operation conditions. However, it has brought drawbacks for DC-link power decoupling with the requirement of a larger capacitor bank, faster voltage regulation, etc., to maintain a constant DC-link voltage which increases the overall size and cost. In this paper, a DC-link decoupling technique using a nonlinear control algorithm is proposed to perform rapid DC-link voltage regulation for multi-input grid-connected inverters. With the implementation of a nonlinear observer, the power fed into the DC-link from multiple inputs is estimated by the proposed control algorithm and can be rapidly compensated by the inverter minimizing the DC-link voltage fluctuation. The effectiveness of the proposed nonlinear power decoupling control algorithm is verified by comparing the DC-link performance with a conventional control algorithm through both simulation results on a MATLAB platform and experimental verification on a grid-connected inverter prototype.