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.