Consensus-Based Current Sharing and Voltage Balancing in DC Microgrids with Exponential Loads

TL;DR

This paper introduces a novel distributed control scheme for DC microgrids that ensures current sharing and voltage balancing, accommodating complex load types and guaranteeing stability and robustness through theoretical analysis and simulations.

Contribution

A new consensus-based secondary control method for DC microgrids that handles exponential loads and guarantees steady-state objectives with plug-and-play capability.

Findings

Achieves steady-state current sharing and voltage balancing.

Ensures stability under various load conditions.

Demonstrates robustness through simulations.

Abstract

In this work, we present a novel consensus-based secondary control scheme for current sharing and voltage balancing in DC microgrids, composed of distributed generation units, dynamic RLC lines, and nonlinear ZIE (constant impedance, constant current, and exponential) loads. Situated atop a primary voltage control layer, our secondary controllers have a distributed structure, and utilize information exchanged over a communication network to compute necessary control actions. Besides showing that the desired objectives are always attained in steady state, we deduce sufficient conditions for the existence and uniqueness of an equilibrium point for constant power loads -- E loads with zero exponent. Our control design hinges only on the local parameters of the generation units, facilitating plug-and-play operations. We provide a voltage stability analysis, and illustrate the performance and robustness of our designs via simulations. All results hold for arbitrary, albeit connected, microgrid and communication network topologies.