MODEL PREDICTIVE CONTROL FOR HYBRID MICROGRID IN ISLANDED MODE OF OPERATION

Abstract

In last few decades, electricity generation through fossil fuel resources initiate adverse impact on the environment. Moreover, fossil fuel resources are relinquishing day by day. Therefore, the microgrid is an effective way to integrate the renewable energy resource in current power system. A microgrid is a type of grid that has local distributed generations (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 is the AC microgrid because the integration of DGs in power system is easily done and existing network utilities are connected to AC grid. Although maximum distribution networks are AC, ESS units, addition of DC modules and DG-based loads is included. The features of both AC and DC are combined in hybrid AC/DC microgrid. In hybrid microgrid, the three phase AC/DC bidirectional converter knowns as inter linking converter is responsible for the power conversion. It can operate both in rectification mode as well as inversion 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 fulfil the local demand. This study proposes the FCS–MPC control scheme for the bidirectional converter in hybrid microgrid. Proposed scheme anticipates future value of the system at each sampling instant for every switching states using system’s exact mathematical model. After this, for the next sampling instant optimum action is applied using cost function. The proposed MPC model for bidirectional converter is verified for its robustness and effectiveness using MATLAB/ Simulink.