IoT-Based Microgrid Central Controller to Adaptively Tune Virtual Complex Impedance for Accurate Power Sharing

Isolated microgrids (MGs) suffer from inaccurate power sharing due to mismatched feeders’ impedances when operated with droop control. Therefore, this work proposes a MG central controller (MGCC) based on the Internet of Things (IoT) to solve this problem. IoT-based MGCC tunes a virtual complex impedance to overcome the problem of feeders mismatching and operating the system with accurate power sharing. It collects the output reactive powers of distributed generators (DGs) to calculate the reference reactive power value, which is utilized through a PI controller to estimate the virtual inductance. Then, the virtual inductance is used to adjust the value of the virtual resistance. The same concept is used to design a damping resistance, which is estimated through a PI controller for the active power error signal. This system takes into account the virtual inductance to decouple the active and reactive powers to facilitate the operation of the droop control, the virtual resistance to reduce the voltage distortion at the point of common coupling (PCC), and the damping resistance to reduce the oscillations that may occur in the MG system during changing the operating points of the connected loads correct.