Voltage Stabilization in a DC MicroGrid by an ISS-like Lyapunov Function implementing Droop Control

The interconnection of renewable energy sources with storage systems through a Direct Current (DC) MicroGrid is one of the best ways to deal with the need for reliable power networks. An approach based on the “System of Systems” philosophy using distributed control methodologies is developed here with the purpose to share the duty to ensure grid voltage stability among a number of devices ensuring fast response. The closed-loop stability proof is based on an Input-to-State-Stable (ISS) like Lyapunov function.

I. Introduction

Recently the use of Direct Current (DC) MicroGrids has grown significant interest mainly due to some advantages over Alternate Current (AC) ones [1]. Indeed, DC grids favour the integration of renewable energy sources (renewables), especially photovoltaic (PV), storages as batteries or supercapacitors, and modern loads as electric vehicles due to the DC nature of these devices. The two kinds of storages usually work at different time scales: the batteries have the duty to provide energy when it is missing from the renewable sources, while the supercapacitors act to compensate the power transient variations in power production or consumption [2], [3], [4], [5].