Improving the Sharing of Reactive Power in an Islanded Microgrid Based on Adaptive Droop Control with Virtual Impedance
Seyed Mohammad Sadegh Hosseinimoghadam, Masoud Dashtdar, Majid Dashtdar, Majid Dashtdar, Majid Dashtdar
Abstract
Abstract Due to recent advances in power electronics, microgrids based on distributed resources with expandable electronic interfaces are expanding. One of the most common ways to share power between these resources in an islanded microgrid is to use droop control. However, due to the difference in line impedance, reactive power-sharing using this method is not accurate and leads to overload in some sources. To solve this problem, this paper presents a method based on the use of common droop characteristics and uses the potential of the virtual impedance in a distributed resource control system. The voltage droop created by the virtual impedance will increase the accuracy of the reactive power-sharing between sources. To generate the right virtual impedance, local controllers of each resource exchange the required information with the microgrid management center using a low-bandwidth telecommunication link. Then, using the droop characteristic of the virtual impedance- reactive power proposed in the resource control system, the amount of virtual impedance of each source is determined in proportion to the microgrid load and resource capacity. Due to the load changes in the microgrid, the slope of the proposed characteristic is adjusted comparatively. To confirm the efficiency of the proposed method, various scenarios have been tested in low voltage microgrid.