Modelling of Solid-State Transformer to Support the Interconnection of Microgrids for Power Sharing and Harmonic Compensation During Islanded Operation

Abstract

The concept of mcirogrids has gained popularity in the distribution of electricity to the final consumer. Microgrids integrating energy storage devices, combined heat and power system (CHP) and renewable energy generation are especially becoming attractive to industrial consumers –such as industrial parks – due to environmental and economic benefits. However, the intermittence of renewable energy sources imply that storage is essential for economic operation. However, technological limitations of storage solutions for the grid imply that we need to consider supplying the power into the main grid. However, grids are designed for unidirectional operation, which implies that mcirogrids cannot receive and send power to the grid. This research paper, shows the potential for SSTs to support power-sharing among islanded microgrids. The microgrids are interconnected through the low-voltage medium, which implies that they can send and receive power from the main grid. Simulations through MATLAB demonstrate that the SST can support the integration of renewable energy sources at the low-voltage DC bus. Furthermore, advanced controls – particularly, particle swarm optimization – can be implemented to mitigate harmonics (only 1.17% in the presence of non-linear loads and 0.36% in the presence of resistive loads alone) and voltage imbalance (the voltage unbalance factor is less than 1%) at the microgrid level. Microgrids generating excess power can also share with neighboring microgrids in the absence of the main grid (for instance, during a fault). This research is instrumental in reconfiguring conventional grids to meet the needs of modern power system requirements.