MODELING OF AC/DC HYBRID MICROGRID WITH ITS CONTROL

Abstract

To fulfill the day by day increasing demand for electrical energy and to reduce the carbon emissions, renewable resources-based energy generation has replaced the traditional electrical generations. A microgrid is nothing but an interconnection of the various loads and the distributed energy resources (DER) based generators that works as a controllable system. A number of reverse conversions are required for DC or AC microgrid individually. Hence, the concept of hybrid microgrid becomes very important for reduction of these conversions. The hybrid microgrid connects the DC and AC networks using the bidirectional converters. DC and DC sources as well as the loads are connected to their respective side i.e., AC or DC in the hybrid microgrid. A control mechanism is proposed for proper transfer of power from AC to DC side and vice-versa. The variation of irradiance is tracked using perturb and Observe (P&O) algorithm based maximum power point tracking (MPPT) technique to extract the maximum output power from the PV arrays. DC-DC boost converter is used to raise the output voltage level of PV array and to stabilize the dc bus voltage. Battery with the bidirectional dc-dc converter is used as energy storage system of the proposed hybrid microgrid and wind turbine based doubly fed induction generator (DFIG) is used to simulate the ac source. Interlinking converter for transferring the power between ac and dc side of the hybrid microgrid is used. Here, a small hybrid microgrid is modelled and the simulation has been done using MATLAB. Only the grid connected mode of operation of the hybrid microgrid is considered and the results show the characteristics of PV array system, PV power tracking the MPP using the MPPT and DC link voltage, current. Also, the DFIG power output, DC and AC load power, and the grid power is also shown in the results obtained from the simulation of the proposed model of the hybrid microgrid.