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

Jaesang Park, Alireza Askarian, Srinivasa Salapaka

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.

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

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.
Paper Structure (18 sections, 2 theorems, 18 equations, 6 figures)

This paper contains 18 sections, 2 theorems, 18 equations, 6 figures.

Table of Contents

  1. INTRODUCTION
  2. Overview of The Conventional GFL and GFM Inverter
  3. Modeling of Inverter connected to a grid
  4. Response of Conventional GFL to perturbation
  5. Response of GFM to perturbation
  6. Proposed GFL controller
  7. Power-injecting dynamics
  8. Design of the controller
  9. Reference tracking
  10. Stability
  11. Robustness against a high-frequency perturbation
  12. Smooth Transition between GFL and GFM
  13. Proposed transition strategy
  14. GFL to GFM
  15. GFM to GFL
  16. ...and 3 more sections

Key Result

Proposition 1

There exists a finite $\alpha>0$ during the transition.

Figures (6)

  • Figure 1: The model of an inverter with LC filter connected to a grid.
  • Figure 2: Block diagram of droop-based power injecting dynamics
  • Figure 3: Power reference (blue line) tracking of proposed GFL (red, orange, and purple line correspond to $\omega_{lpf}$ values of $4\pi\text{ rad/s}$, $10\pi\text{ rad/s}$, and $20\pi\text{ rad/s}$ respectively)
  • Figure 4: Response against sudden load change with Conventional (blue line) and Proposed GFL(red, orange, and purple line correspond to $\omega_{lpf}$ values of $4\pi\text{ rad/s}$, $10\pi\text{ rad/s}$, and $20\pi\text{ rad/s}$ respectively)
  • Figure 5: Power sharing between GFM and proposed GFL under slow load change: Blue represents the proposed GFL, Red represents GFM, and Orange represents the total load.
  • ...and 1 more figures

Theorems & Definitions (2)

  • Proposition 1
  • Proposition 2