Energy Control of Grid-forming Energy Storage based on Bandwidth Separation Principle

TL;DR

This paper proposes an improved energy storage control method for grid-forming systems that ensures stable frequency regulation by restoring energy reserves using bandwidth separation, addressing inertia limitations.

Contribution

It introduces a bandwidth separation-based energy recovery control for energy storage in virtual synchronous machines, considering state-of-charge constraints.

Findings

Effective energy recovery restores energy reserves.

Simulation verifies improved frequency support.

Addresses inertia and energy limitations.

Abstract

The reduced inertia in power system introduces more operation risks and challenges to frequency regulation. The existing virtual inertia and frequency support control are restricted by the normally non-dispatchable energy resources behind the power electronic converters. In this letter, an improved virtual synchronous machine (VSM) control based on energy storage is proposed, considering the limitation of state-of-charge. The steady-state energy consumed by energy storage in inertia, damping and frequency services is investigated. Based on bandwidth separation principle, an energy recovery control is designed to restore the energy consumed, thereby ensuring constant energy reserve. Effectiveness of the proposed control and design is verified by comprehensive simulation results.