Grid-Coupled Dynamic Response of Battery-Driven Voltage Source Converters

TL;DR

This paper investigates the dynamic behavior of battery-driven grid-forming converters in islanded microgrids, focusing on control strategies for DC-link voltage regulation under load changes and reduced capacitance.

Contribution

It introduces a zero-order battery model for effective dynamic analysis and demonstrates how AC measurements can enhance controller performance, enabling lower capacitance use.

Findings

Zero-order battery model accurately captures dynamics for studied timescales.

Including AC measurements improves DC/DC controller performance.

Reduced DC-side capacitance is feasible with improved control, enhancing reliability.

Abstract

With the increasing interest in converter-fed islanded microgrids, particularly for resilience, it is becoming more critical to understand the dynamical behavior of these systems. This paper takes a holistic view of grid-forming converters and considers control approaches for both modeling and regulating the DC-link voltage when the DC-source is a battery energy storage system. We are specifically interested in understanding the performance of these controllers, subject to large load changes, for decreasing values of the DC-side capacitance. We consider a fourth, second, and zero-order model of the battery; and establish that the zero-order model captures the dynamics of interest for the timescales considered for disturbances examined. Additionally, we adapt a grid search for optimizing the controller parameters of the DC/DC controller and show how the inclusion of AC side measurements into the DC/DC controller can improve its dynamic performance. This improvement in performance offers the opportunity to reduce the DC-side capacitance given an admissible DC voltage transient deviation, thereby, potentially allowing for more reliable capacitor technology to be deployed.