A Nested-Iterative Newton-Raphson based Power Flow Formulation for Droop-based Islanded Microgrids

Abstract

In this paper, an iterative novel power flow technique is proposed to obtain the operating point of Droop Based Islanded Microgrid (DBIMG). The proposed technique considers system frequency as an additional variable to obtain the steady-state operating point of the system. To generalize the proposed technique, four operating modes of Distributed Generations (DGs) including droop control, isochronous, PV and PQ mode are considered. In this study, the formulated power flow problem consists of a set of non linear and linear power flow equations. To solve these set of equations, a Nested-Iterative Newton-Raphson algorithm is proposed. The proposed algorithm is implemented on several test systems including 6-bus, 22-bus, 38-bus, 69-bus, and 160-bus. To examine the robustness and effectiveness of the proposed algorithm, the power flow solutions obtained by implementing the proposed algorithm are compared with the power flow solutions obtained by implementing the existing Newton-Raphson algorithms including Modified Newton-Raphson (MNR), Newton Trust-Region (NTR) and time-domain simulator: PSCAD/EMTDC. The results show better efficiency and superior convergence of the proposed algorithm in comparison to the existing algorithms. © 2019 Elsevier B.V.