Direct Backward/Forward Sweep Algorithm for Solving Load Power Flows in AC Droop-Regulated Microgrids

Abstract

We propose an algorithm capable of solving the load power flow problem in ac droop-regulated microgrids. Based on radial distribution networks, these systems lack a slack bus for facilitating the computation by means of conventional methods. Rather than having the stiff bus that provides a voltage reference and supplies the necessary power, the voltage and power regulation must be shared among the distributed resources as a function of their frequency and voltage droop functions. The proposed algorithm is based on the well-known backward/forward sweep algorithm, conventionally employed to solve grid-connected radial load power flows, with the interesting property that they are derivative-free. We have expanded the algorithm to cope with the lack of slack bus. In this paper, we show the theoretical foundation and provide some tests with ex-post computations to investigate the coherence of the results.