A Novel Adaptive Voltage Integral Control for Improving Power Sharing and Circulating-Current Resonance in Islanded Micro-grid

Abstract

Different with conventional uninterrupted power supply (UPS) system, improving power sharing and reducing circulating-current resonance are important to islanded micro-grid because of the unstructured impedance networks decided by the uneven distribution of power converters and electrical loads. Virtual impedance control, as an improved droop control, is widely used to solve these problems. However, voltage drop of the load will be aggravated with increase of the virtual impedance. This paper aims to reveal disadvantages of the virtual impedance control and a novel adaptive voltage integral control is proposed to solve the voltage drop problem and enhance power sharing autonomously through key parameters. The proposed adaptive control is compared with the virtual impedance control in aspect of circulating-current resonance by impedance analysis. The correctness and effectiveness of the proposed method are verified by simulations and experiments.