Voltage-Independent Active-Power Droop Coefficient for Enhanced Andronov-Hopf Oscillator Grid-Forming Inverters

TL;DR

This paper introduces an enhanced Andronov-Hopf oscillator for grid-forming inverters with a voltage-independent active power droop coefficient, improving stability, power sharing, and dynamic response.

Contribution

The paper proposes a novel active power droop strategy for AHO-based inverters that maintains dynamic benefits while ensuring voltage independence.

Findings

Improved steady-state performance and power sharing accuracy.

Enhanced frequency and voltage support capabilities.

Validated stability and dynamic response through experiments.

Abstract

In recent years, virtual oscillator control, particularly the Andronov-Hopf oscillator (AHO), has received widespread attention for controlling grid-forming (GFM) inverters due to their superior dynamic response. However, traditional AHO systems feature droop coefficients that are dependent on the oscillator voltage amplitude, limiting their ability to maintain consistent grid support during disturbances and resulting in power-sharing inaccuracies. This paper presents an enhanced AHO (EAHO) strategy, where the active power droop coefficient is no longer a function of the voltage amplitude and retains the key dynamic benefits of the original AHO. The EAHO improves both frequency and voltage support and ensures accurate power sharing with other GFM inverters in grid-connected and stand-alone modes. Extensive comparative and small-signal analyses, alongside experimental validation on 2.5 kVA single-phase inverters, confirm the EAHO's improved steady-state performance, enhanced active and reactive power support, and stable operation under varying grid conditions.