Adaptive Virtual Impedance Droop Control of Parallel Inverters for Islanded Microgrids

The droop control strategy, known for its communication-free nature, is widely adopted for the parallel operation of inverter units. However, in microgrids, mismatches in line impedances and various measurement inaccuracies often lead to imbalanced reactive power sharing among inverters and significant circulating current. To address these challenges, this paper proposes an adaptive droop control method that relies solely on local measurements from each inverter, eliminating the need for communication. The proposed approach integrates the deviation between the ratio of reactive power to output voltage and its reference value to generate an Adaptive Virtual Impedance Droop Control (AVIDC) mechanism. This enables a dynamic balance between reactive power output and voltage drop. The simulation and experimental results validate the effectiveness of the proposed control strategy, demonstrating a significant improvement in the accuracy of reactive power sharing.