A Grid-Forming Multi-Port Converter using Unified Virtual Oscillator Control

Abstract

A multi-port converter (MPC) consisting of a grid-forming port, a DC port, and a split-phase-AC port is proposed which can be used as building blocks in hybrid AC-DC systems such as community microgrids enabling intra-community and inter-community energy sharing. Commercially available off-the-shelf SiC power modules are used to achieve a modular hardware design for ease of assembly and maintenance. Unified virtual oscillator control (uVOC) is used to enable grid-forming operation. uVOC enables enhanced fault ride-through with fast over-current limiting; furthermore, operation in grid-connected and islanded modes and seamless transition between the two are achieved. Supervisory control and data acquisition (SCADA) with secondary and tertiary level reference dispatch capability is obtained through an integrated cyber node enabled by open-source hardware and software. Experimental results using a full-scale prototype is provided to validate the design. Using a battery energy storage system (BESS) connected at the DC port of the MPC, black-start, islanded and grid-tied operation, unintentional islanding, and grid re-synchronization capabilities are demonstrated.