A new control method based on droop and Thevenin theorem to improve responses of VSIs in islanded MG

Abstract

In this article, a new control method based on ordinary droop and Thevenin impedance from DG inverter-side in islanded microgrids is presented and the results have been discussed and compared to each other for both situations. In spite of improvements in steady state responses and rather desirable convergence in parameters such as circulating current among inverters, active and reactive powers, and the proportion of active power generated by inverters, ordinary droop provides inappropriate and long transient responses which is not favorable. In the novel method, the Thevenin impedance from inverter-side is utilized in one of the equations of droop leading up to significant improvement in transient responses of introduced parameters, both in their amplitude and response length time. Diagrams plotted for each of them, indicates these improvements.