Design and Implementation of Iterative Learning Controller for Power Management in Hybrid Microgrid

Abstract

The depletion of fossil fuels, the increase in load demands, and the evolution of newlinerenewable energy sources make the power sectors to focus on renewable power generation.The combination of various distributed energy resources, storage systems and loads with specified electrical limitation and suitable controllers forms a microgrid and it works as a controllable sole unit from grid perspective. It could be operated in islanded mode or grid-connected mode. In grid-connected mode, the generated excess power from the distributed sources are exported to the utility grid (UG) or power is imported from the UG when there is less power generation. When there is a failure or scheduled maintenance at the UG, the microgrid is isolated from UG and operates in islanded mode. Microgrid is in transition mode, when switching occurs from islanded to grid-connected mode and vice versa. AC/DC microgrids have been developed independently for their merits and demerits. The integration of AC and DC microgrids forms a Hybrid Micro Grid (HMG), which combines the benefits of both AC/DC subgrids. Due to the various advantages of HMG and its wide applications, multiple forms of HMG systems have been developed in this research with solar, wind, fuel cell, battery and loads. The distributed sources in HMG have variable power output and the existing loads are also dynamic. Since the input sources are intermittent in nature, there is a need for a source-side converter (SSC) to maintain the stable DC output voltage, which is achieved by the dedicated fuzzy logic controllers. To integrate HMG with UG , Grid Side Converters (GSC) have been deployed in the system. These GSC s or bidirectional converter or interlinking converter (IC) located between AC/DC bus in HMG has to be controlled efficiently to maintain stable bus voltages and manage the power flow between UG and HMG under the various modes of operation. For the efficient operation of the IC, there is a need for designing a suitable controller. Maintaining stable AC/DC bus voltage control acti