Adaptive and Distributed Voltage Regulation and Reactive Power Sharing in Islanded Inverter-Based Distribution Networks

Abstract

The increasing usage of Renewable Energy Sources (RES), which are typically interfaced with the grid as Inverter-Based Resources (IBRs), is leading to the formation of Microgrids (MGs) and Networks of MGs (NMGs). MGs and NMGs can operate autonomously in islanded mode. However, there are prevailing operational challenges in terms of voltage and reactive power control in islanded grids, as well as their degree of tradeoff. Although Distributed-Averaging Proportional-Integral (DAPI) control has been proposed in the literature for secondary control of IBRs, its systematic tuning for its degree of voltage regulation against reactive power sharing is not wellexplored. To address this, we propose a local and adaptive gain tuning scheme for autonomous adjustment of IBR voltage regulation and reactive power sharing. The proposed scheme introduces an adaptive gain that inversely correlates voltage regulation and reactive power sharing using voltage deviation. High-fidelity simulations in MATLAB (Registered trademark)/Simulink (Registered trademark) of an islanded and modified IEEE 123 bus test feeder system - as well as an IEEE 13 bus test feeder system with Arduino-based Controller Hardware-In-the-Loop (CHIL) validation - demonstrate adequate adaptive gain control that improves reactive power sharing for any given voltage regulation headroom,that is the remaining margin between the present voltage deviation and the allowable voltage deviation limit.