Control Designs for Critical-Continegency Responsible Grid-Following Inverters and Seamless Transitions To and From Grid-Forming Modes

TL;DR

This paper presents control strategies for grid-following inverters to support grid-forming inverters during contingencies and to enable seamless mode transitions, improving voltage stability and power management in microgrids.

Contribution

It introduces two novel control frameworks for GFL inverters: one for contingency support and another for seamless mode transitions, enhancing microgrid stability and performance.

Findings

Improved voltage regulation during contingencies.

Enhanced power tracking during slow changes.

Reduced transient overshoot during mode transitions.

Abstract

This article introduces two control frameworks: one for Grid-Following (GFL) inverters aiding Grid-Forming (GFM) inverters in voltage regulation during large contingency events and optimizing power transactions under normal conditions; and another for seamless transitions between grid-tied and grid-isolated setups, managing voltage transient characteristics. In microgrids, GFM inverters regulate voltage, while GFL inverters handle power transactions. The proposed GFL control detects abrupt load/generation changes, adjusting power transactions using local storage to support GFM inverters during contingencies. Additionally, a transition control ensures smooth GFL-GFM shifts, reducing power and voltage fluctuations. Simulation results validate improved voltage regulation during contingencies and enhanced power tracking during slow changes, alongside minimized transient overshoot.