Abstract:
In recent years, electricity generation from standard fossil fuel resources originate critical influence
on the environment. Moreover, fossil fuel resources are evacuating day by day. Therefore, the
microgrid is an effective way of integrating current power system and renewable energy resources.
A microgrid is a type of grid that has local distributed generators (DGs) and it is connected to the
national grid but also able to work independently and have effective control. Hybrid AC/DC
microgrid, DC microgrid and AC microgrid and are the three categories of microgrid. The
generally used configuration in the AC microgrid because it provides a straightforward way for
the integration of DG modules and existing network utilities with minimal modifications. Although
maximum distribution networks are AC, ESS units, addition of DC modules and DG-based loads
is included. More characteristics include opening the entryways of distribution networks which are
based on DC. The features of both AC and DC are combined in hybrid AC/DC microgrid. In hybrid
microgrid, the three phase AC/DC bidirectional converter is required for power conversion. It can
operate both in rectification mode and inverter mode. In rectification mode, it can regulate power
on the DC side or it can maintain voltage on the DC side. In inverter mode, it can further operate
in two modes, islanded mode and grid connected mode. In grid connected mode, national grid
controls the frequency and voltage of the microgrid while power is control by the DG. In the
islanded mode, DG control the frequency and voltage of a microgrid and also fulfill the local
demand. Bidirectional Voltage Source converter (VSC) is an essential component in hybrid
microgrids. The challenges in bidirectional converter are; control of power flow in both directions
while maintaining stability, efficient transitions between the modes and efficient control of nonlinearity. This study proposes the FCS–MPC control scheme for the bidirectional converter in
hybrid microgrid. In the proposed scheme, future value of the system at each sampling instant is
forecasted for every switching states using system’s mathematical model. After this, for the next
sampling instant optimum action is applied using cost function. Converter switching frequency is
reduced using tow-step horizon-based cost function (CF). The proposed MPC model for
bidirectional converter is verified for its robustness and effectiveness using
MATLAB/SIMULINK.
