Synchronverter coupled to a lithium-ion bank for grid frequency and voltage supports and controlled charge-discharge

Abstract

Many control strategies for grid-interfacing voltage source inverter (VSI) of distributed generation (DG) units have been reported for grid support, among them virtual synchronous machine (VSM) techniques, in particular the Synchronverter which has the ability to operate in voltage and frequency support mode, in active and reactive power control mode, in synthetic inertia and in conventional grid-side control of DG. The VSM-based VSI has its support capacity expanded by battery energy storage systems (BESS). In this work it proposes the Synchronverter to control a lithium-ion BESS connected to DC-bus of DG seeking grid frequency and voltage support. Since Synchronverter allows the conventional grid-side control which allows bi-directional flow, BESS charge-discharge is controlled without using DC/DC converter. Simulation results demonstrate the effectiveness of the Synchronverter for both of support and change-discharge control.