Internal Model based Smooth Transition of a Three-Phase Inverter between Islanded and Grid-Connected Modes


Recent technical advances in control, protection and interconnection of distributed power generation units imply that it is practically viable and economically profitable to keep them as backup generators in isolated operating modes. Therefore, along with the development of islanding detection techniques, seamless operation in transition between islanded and grid connected modes is required and more sophisticated control strategies are needed to recognize the existing working condition and adjust the performance to meet the strict standards of grid interconnection. This paper presents a new adaptive control structure, based on internal model control (IMC), which uses multiple models and an inherent islanding detection method through an optimized switching mechanism to tune the operation of a three-phase inverter under transitions between islanded and grid-tied conditions. By applying a power synchronization method, the system emulates the operation of a synchronous machine which is needless to rely on a phase-locked loop to synchronize during the transitions. Hardware co-simulation environment in Simulink/PLECS and Xilinx System Generator have been utilized to evaluate the transient behavior of the controller in discretized domain and verify its robustness during parameter variations and load switching conditions. Various switching rules have been applied and a comparison of their effect in transient response is demonstrated. The results, taken from several case studies, confirm the significant robustness of the proposed control methodology.


Electrical and Computer Engineering

Research Center/Lab(s)

Center for Research in Energy and Environment (CREE)

Second Research Center/Lab

Intelligent Systems Center

Keywords and Phrases

Adaptive Control; Distributed Energy Resources (DER); FPGA Implementation; Hardware-In-The-Loop (HiL); Internal Model Control (IMC); Multiple Models; Phase-Locked Loop (PLL); Point of Common Coupling (PCC); Switching Rule; Transient Response; Voltage Source Converter (VSC)

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2020 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Mar 2020