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

Abstract

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.

New hybrid‐microgrid topology using a bidirectional interleaved converter as a robust power interface operating in grid‐connected and islanded modes

“…This system uses a back-to-back converter to perform a PFI between the AC utility bus and the AC microgrid bus in such a way to obtain a high-power quality at the AC microgrid. This topology may require a power interface between the DC link of the back-to-back converter and the DC microgrid bus due to the difference in their voltage levels [15,16].…”

“…In [15,16], the first and the second control objectives were deeply studied with the system operating in the grid-connected mode. However, the operation of the system in islanded mode, and the proper control law to enable it, have not been discussed.…”

“…Nevertheless, it is also demonstrated that this tuning technique resulted in poor disturbance-rejection dynamic behaviour. In order to solve this issue, a voltage regulator tuning method is proposed in [16] aiming at improving the output voltage control performance during power variations in the grid-connected operation mode. In this work, the following input-voltage v C1 controller design method ((32) and (33)) is proposed, aiming at achieving a fast disturbance-rejection response for the boost mode operation of the interleaved converter in the islanded mode.…”

“…This characteristic leads to a reduction of the output capacitance resulting in a lighter solution. One of the concerns related to this converter is the possibility of the occurrence of phase-current imbalance, which can be solved by using a proper control strategy [15,16].…”

“…Several applications of this converter have been proposed in the literature, such as regulated power sources with high reliability and low weight, energy storage systems and electric vehicles [17][18][19][20][21][22][23][24][25][26][27][28]. The usage of this converter as a PFI between DC buses of different microgrids was originally proposed in [16]. The focus of the work is to analyse the control performance regarding disturbancerejection capability only in grid-connected mode.…”