The voltage regulation of inverter-based islanded microgrids with virtual impedance frequently deteriorates under higher load demand due to voltage drops across the virtual impedance and the feeder. Conventional droop control with a fixed virtual resistance (Rv) improves current sharing by impedance matching but amplifies voltage sag as the load increases. This paper proposes a novel load-adaptive virtual resistance strategy for decentralized control of low-voltage microgrids. Unlike conventional fixed virtual resistance methods and many existing adaptive virtual impedance approaches, the proposed method directly embeds a prescribed voltage-regulation coefficient into the Rv formulation. The adaptive virtual resistance is analytically determined using the allowable voltage deviation, inverter rating, feeder resistance, and locally measured dq-axis voltage and current components. As the load demand increases, the calculated virtual resistance decreases automatically, thereby limiting the voltage drop introduced by the virtual resistance while preserving proportional power sharing among parallel inverters. The adaptive law is implemented in the dq reference frame using locally measured voltages and currents. A cascaded PI controller structure comprising an inner current loop and an outer voltage loop is used for control. Comprehensive tests under various load change scenarios are conducted to evaluate the proposed approach, and the results demonstrate improved voltage regulation under wide load variations. Moreover, the proposed approach improves reactive power sharing, which is a significant challenge in inverter-based microgrids. The proposed method is simple, fully decentralized, and can be integrated into existing droop-controlled inverters without communication links.
- Open Access
- Article
A Load-Adaptive Virtual Resistance Strategy for Decentralized Control of Low-Voltage Islanded Microgrids
Author Information
Received: 29 Jul 2026 | Revised: 14 Sep 2026 | Accepted: 17 Sep 2026 | Published: 23 Sep 2026
Abstract
Keywords
adaptive virtual resistance | droop control | islanded operation | low-voltage microgrid | reactive power | voltage regulation
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