Control Design, Stability Analysis and Experimental Validation of New Application of an Interleaved Converter Operating as a Power Interface in Hybrid Microgrids

This paper presents a new and specific use of a bidirectional interleaved converter to perform a power interface in hybrid microgrids. The converter is responsible for regulating the power flow between the direct-current (DC) microgrid and the rest of the hybrid microgrid by controlling the DC microgrid voltage. The authors present a detailed modeling of the mentioned system in order to develop the system control design and a stability analysis. In addition, the authors propose a new control design strategy aiming at improving the voltage control disturbance rejection characteristic, while maintaining a good dynamic behavior regarding the reference tracking functionality. In this hybrid microgrid topology, a back-to-back converter connects the main grid to the AC microgrid. The main objective of this converter is to provide a high-power-quality voltage to critical and sensitive loads connected to the microgrid. The interleaved converter adjusts the DC microgrid voltage according to the operational voltage of the back-to-back converter DC link. In the DC microgrid case, the variation of load and generation connection could lead to serious voltage sag and oscillations that could be harmful to the sensitive loads. The voltage controller must be capable of rejecting these disturbances in order to maintain a high-power-quality voltage. Furthermore, experimental results are provided in order to validate this specific application of the interleaved converter and the presented control design strategy.