Grid-Forming Vector Current Control FRT Modes Under Symmetrical and Asymmetrical Faults

TL;DR

This paper develops fault ride-through strategies for grid-forming vector current control in converters, enabling fault current support and synchronization during symmetrical and asymmetrical grid faults, enhancing grid stability.

Contribution

It introduces modular FRT strategies for GFVCC that incorporate negative-sequence control, addressing both symmetrical and asymmetrical faults, a novel extension for improved fault handling.

Findings

FRT strategies enable converters to support fault currents during grid faults.

Control scheme successfully maintains synchronization during symmetrical and asymmetrical faults.

Case studies demonstrate effectiveness in various grid configurations.

Abstract

Recent research has shown that operating grid-connected converters using the grid-forming vector current control (GFVCC) scheme offers significant benefits, including the simplicity and modularity of the control architecture, as well as enabling a seamless transition from PLL-based grid-following control to grid-forming. An important aspect of any grid-connected converter control strategy is the handling of grid-fault scenarios such as symmetrical and asymmetrical short-circuit faults. This paper presents several fault ride-through (FRT) strategies for GFVCC that enable the converter to provide fault current and stay synchronized to the grid while respecting the converter hardware limitations and retaining grid-forming behavior. The converter control scheme is extended in a modular manner to include negative-sequence loops, and the proposed FRT strategies address both symmetrical and asymmetrical faults. The proposed FRT strategies are analyzed through case studies, including infinite-bus setups and multi-unit grids.