Model-Free Power Control for Low-Voltage AC Dispatchable Microgrids with Multiple Points of Connection

Abstract

This paper proposes a modified version of the power-based control (MPBC) applied to microgrids (µGs) with multiple points of connection (i.e., utility grid itself or any other neighboring µG). Using the MPBC, single-phase distributed energy resources (DERs) arbitrarily connected between the phases share the amounts of balanced power, while the unbalanced and homopolar power are steered only to the line-to-neutral inverters. The control technique is based on a three-level hierarchical control using narrow bandwidth, low data rate communication that properly coordinates the DERs connected to three-phase four-wire µGs. The MPBC allows the DERs to steer power flow at any of the multiple points of common coupling of a multi-PCC dispatchable µG. The modified control proposed herein is evaluated through simulation results using MATLAB/SIMULINK considering a real urban distribution grid with typical operational elements and conditions. When compared to the original power-based control (PBC), results show that a meshed µG may reach power benchmarks with accommodation time 80% lower when applying MPBC. Moreover, it may also lead to significant power loss reduction (about of 5%) in some studied cases.

Keywords

• dispatchable microgrids
• multi-PCC microgrids
• hierarchical control
• power sharing