Operational limits of a three level neutral point clamped converter used for controlling a hybrid energy storage system

•The control of a hybrid storage system using a Three Level NPC converter is analysed.•A sinusoidal PWM with an offset injection is used to control the storage system.•The operation of the selected converter is analysed in its entire operation range.•The operational limits of the Three Level NPC converter are defined.

This work analyses the use of a Three-Level Neutral Point Clamped (3LNPC) converter to control the power flow of a Hybrid Energy Storage System (HESS) and at the same time interconnect it with the common AC bus of a microgrid.Nowadays there is not any storage technology capable of offering a high energy storage capacity, a high power capacity and a fast response at the same time. Therefore, the necessity of hybridising more than one storage technology is a widely accepted idea in order to satisfy the mentioned requirements.This work shows how the operational limits of the 3LNPC converter can be calculated and integrated in a control structure to facilitate an optimal use of the HESS according to the rules fixed by the user.