드룹 제어 기반 그리드 포밍 인버터의 무효 전력 균등 분담 제어기 연구

Abstract

This paper proposes a novel droop control methodology that calculates the accurate voltage drop values in the DQ coordinate system and compensates them using a feedforward approach, thereby solving the reactive power control sharing errors caused by line impedance voltage drops. Multiple (Grid-Forming) GFM inverters, not directly connected to the PCC, are configured with varying line impedances, and the proposed droop controller estimates and compensates for the voltage drop components, corresponding to the line impedances in the Direct-Quadrature (DQ) coordinate system. This principle effectively zeroes out the impedance components as seen from the output end of the GFM inverters. The proposed droop control method operates by using DQ synchronous coordinate transformation, instead of applying AC voltages directly. Its performance in ensuring stable and equal reactive power sharing by two GFM inverters, both in grid-connected and standalone operations, has been verified through simulations and experiments. © 2024 Korean Institute of Electrical Engineers. All rights reserved.

This paper proposes a novel droop control methodology that calculates the accurate voltage drop values in the DQ coordinate system and compensates them using a feedforward approach, thereby solving the reactive power control sharing errors caused by line impedance voltage drops. Multiple (Grid-Forming) GFM inverters, not directly connected to the PCC, are configured with varying line impedances, and the proposed droop controller estimates and compensates for the voltage drop components, corresponding to the line impedances in the Direct-Quadrature (DQ) coordinate system. This principle effectively zeroes out the impedance components as seen from the output end of the GFM inverters. The proposed droop control method operates by using DQ synchronous coordinate transformation, instead of applying AC voltages directly. Its performance in ensuring stable and equal reactive power sharing by two GFM inverters, both in grid-connected and standalone operations, has been verified through simulations and experiments.