A Fully Filter-Based Decentralized Control With State of Charge Balancing Strategy for Battery Energy Storage Systems in Autonomous DC Microgrid Applications

Xin Lin,Ramon Zamora,Craig A. Baguley

doi:10.1109/access.2021.3052924

Abstract

State of charge (SoC) imbalance and dc bus voltage deviations are significant issues for distributed battery energy storage systems in autonomous dc microgrid applications. Accordingly, a high-pass filter (HPF) based SoC balancing method is proposed to achieve SoC balance by considering different SoCs and capacities; A band-pass filter (BPF) based power droop control is used to accomplish power-sharing and voltage compensation. Through this approach, battery storage units (BSUs) with higher SoC and capacity deliver more power during discharging mode than those with lower SoC and capacity. During charging mode, those BSUs with higher SoC and lower capacity are controlled to absorb less power than those with higher capacity and lower SoC. Therefore, SoC balance can be achieved between distributed BSUs. Further, the dc bus voltage is maintained within the desired range by adopting the proposed method. In addition, the control method employed also considers the impact of line resistance. The proposed control strategy is implemented in a fully decentralized way which does not require any communication link, while maintaining system stability. MATLAB/Simulink and processor-in-the loop (PIL) simulation results verify that the proposed control strategy is effective and feasible.

Highlights

The share of electricity from renewable energy resources (RERs) is increasing
A microgrid is a small-scale power system that has a pivotal role in the integration of RERs, along with battery storage units (BSUs), into future societies [1], [2]
The present research proposes a filter-based droop control to achieve State of charge (SoC) balancing by considering the different SoCs and capacities among BSUs in a dc microgrid

Summary

INTRODUCTION

The share of electricity from renewable energy resources (RERs) is increasing. In [24], a droop based fuzzy logic control approach is proposed to balance the SoC among batteries by regulating virtual resistances in low voltage dc microgrids. In this paper, a novel filter-based droop control with SoC balancing scheme for dc microgrids is proposed, which does not require any local communication systems among BSUs. The major contributions of this paper are summarized as follows: VOLUME 9, 2021 a) The proposed HPF-based SoC balancing approach can achieve SoC balance by considering different capacities and SoCs among BSUs. b) Voltage recovery and power sharing are achieved by introducing BPF-based power droop control. The voltage deviation caused by the power droop control and SoC balancing scheme is reduced by the proposed fully decentralized method.

CONTROL PARAMETERS DESIGN AND SYSTEM

Findings

CONCLUSION