Synchronization of three-phase converters and virtual microgrid implementation utilizing the Power-Hardware-in-the-Loop concept

This paper addresses the timely issues of synchronization and application of three-phase power converters connected in parallel utilizing the Power-Hardware-in-the-Loop concept. Without proper synchronization, distinguishing the currents circulating between the converters are unclear. The paper centers on control methodology for achieving precise phase synchronization for equal load sharing, with minimum current circulation between the paralleled power converter modules, and robust dynamic system control under different transient conditions. One of the possible applications for the configuration presented in this paper is the conceptual virtual microgrid, which utilizes the reactive power compensation ability of the Static Synchronous Compensator (STATCOM). The microgrid behavior and load dynamics are simulated with a real-time digital simulator which generates appropriate control commands to a power electronics based voltage amplifier interfaced via a cascaded LC-LC type filter to a variable speed drive (VSD). This is necessary as reactive power control is a critical consideration in improving the power quality of power systems. To compensate for reactive power, the STATCOM controller will be developed and integrated into the proposed virtual microgrid system. This concept provides a solution for de-risking these costs as it utilizes the PHIL concept in conjunction with high-fidelity microgrid model and detailed load dynamics. Selected experimental results on two, 25-kVA and 15-kVA, converters in parallel are presented.