Smart transformer based power flow control in multi microgrid system

Abstract

In order to increase the flexibility of a microgrid, the active power exchange between a microgrid and the utility grid as well as other microgrids need to be controlled properly. The voltage based control of a Smart Transformer allows the control of active power flow between a utility grid and a microgrid at the point of common coupling (PCC). This paper addresses the control of the active power flow between two microgrids in an islanded mode and also between two microgrids in the grid connected mode with and without encouraging the participation of the utility grid. Here, we utilize the voltage based control on a thyristor controlled on load tap changing transformer which makes the Smart Transformer concept even more smart. The thyristor based Smart Transformer at the PCC enables faster switching and minimizes the arcing problems of a normal on-load tap changing transformer. The distributed generation units in the microgrid should be equipped with a voltage-based droop control strategy which reacts on the voltage change, making the Smart Transformer an element that controls power exchange without the need for any communication to other elements in the microgrid. The experimental simulations performed in MATLAB/SIMULINK follow that a smart transformer allows the power flow control between two microgrids.