Theory, Simulation, and Implementation of Grid Connected Back to Back Converters Utilizing Voltage Oriented Control

Abstract

This work presents a back to back converter topology with the ability to connect two power systems of different voltages and frequencies for the exchange of power. By utilizing indirect AC/AC conversion decoupling is achieved between the power systems with one of the three-phase, two-level voltage source converters performing the AC/DC conversion that maintains the required DC bus voltage level at unity power factor while the other converter operates in all four quadrants supplying/consuming active and/or reactive power with the other power system. The prototype implementation resides at UW-Milwaukee’s USR Building microgrid test bed facility. A possible application topology would be the converter that maintains the DC bus voltage to be connected to the microgrid’s electrical bus of distributed energy sources while the other converter is connected to the utility in order to supply the required active and/or reactive power to support the needs of the grid.