Passivity based Stability Assessment for Four types of Droops for DC Microgrids

TL;DR

This paper evaluates the stability of four droop control types in DC microgrids using passivity concepts, proposing an analytical design approach verified through simulations, enhancing system stability and control.

Contribution

It introduces a passivity-based stability assessment and design method for four droop types in DC microgrids, incorporating bus impedance and low pass filters.

Findings

Passivity-based stability criteria established for four droop types.

Analytical design method verified through time domain simulations.

Improved stability with less conservative passivity conditions.

Abstract

DC microgrids are getting more and more applications due to simple converters, only voltage control and higher efficiencies compared to conventional AC grids. Droop control is a well know decentralized control strategy for power sharing among converter interfaced sources and loads in a DC microgrid. This work compares the stability assessment and control of four types of droops for boost converters using the concept of passivity. EN standard 50388-2 for railway systems provides a reference to ensure system stability in perspectives of converters and system integration. Low pass filter (LPF) in the feedback of the droop control is used to ensure converter passivity. Bus impedance is derived to ensure system passivity with less conservativeness. Analytical approach for design of passive controller for all four types of droops is verified through time domain simulations of a single boost converter based microgrid feeding a Constant Power Load (CPL).