Virtual Slack Bus Newton-Raphson Power Flow (VSB-NRPF) Algorithm for Droop-controlled MVDC Distribution Systems

This letter proposes a virtual slack bus Newton-Raphson power flow (VSB-NRPF) algorithm serving for the PF analysis of droop-controlled medium-voltage direct current (MVDC) systems operating in islanded mode without a slack bus. In the proposed algorithm, one of the original power, current, power/voltage and current/voltage buses is assumed to be a virtual slack bus with an initial rated dc voltage, the value of which is corrected based on the actual PF balance equation at the original bus. The accurate voltage value at the virtual slack bus can be derived with fewer iterations by a novel binary search method with Lagrange interpolation. Simulations conducted in RSCAD using an MVDC test system with six dc buses validate the effectiveness of the proposed VSB-NRPF algorithm.