Transformer Overloading Control by Controlling the Operational-Modes of High-Power Converters

With the increasing penetration of renewable sources and energy storage, high-power converters including voltage source converters (VSCs) and dc/dc converters are getting fair occupation into power grid. These high-power converters could be used to control the transformer's overloading by controlling their operational modes. For a VSC, operational modes include rectification and inversion operation, and for a dc/dc converter, operational modes include buck and boost operation. These operational modes are administrated by a proposed algorithm, which senses the power handled by distribution transformer and keeps it within a designated threshold. The algorithm carries out all this by controlling the power flow from/to grid to/from battery storage. All power converters operate in a closed-loop where reference is tracked by using PI-control. In this paper, the authors have improved the performance of power converters by introducing fuzzy-control. A simulation model including grid, transformer, AC bus, dynamic load, VSC, dc/dc converter and battery-storage has been developed in MATLAB/Simulink environment. A test case of overloading of transformer is simulated and performance of PI-control and fuzzy-control for power converters is evaluated. It is seen that fuzzy-control gives a better performance than PI-control.