Adaptive Droop Control Using Adaptive Virtual Impedance for Microgrids with Variable PV Outputs and Load Demands

Zilin Li, Ka Wing Chan, Jiefeng Hu, Josep M. Guerrero

Research output: Journal article publicationJournal articleAcademic researchpeer-review

12 Citations (Scopus)

Abstract

In microgrids, intermittency of renewable energy sources (RES) and uncertain state-of-charge (SoC) of energy storage systems (ESS) can cause power deficiency to some distributed generation units (DGs). In this case, DGs with power deficiency may not meet the power demand, resulting in voltage collapse or frequency divergence. Unfortunately, this is seldom considered in inverter control design in existing literature. Thus, in-depth investigation into the microgrid performance under renewable energy resource fluctuations and appropriate control methods are urgently needed. In this article, an adaptive droop and adaptive virtual impedance control strategy is proposed. Unlike conventional droop control where the droop coefficients are fixed by assuming the DGs can always meet the load demand, the droop coefficients here are adjusted according to actual solar PV power output. In this way, proper power sharing among DGs can be achieved under renewable energy variation. Furthermore, the impact of varying DG capacities on system stability is mathematically investigated. An adaptive virtual impedance is then incorporated into the adaptive droop method to deal with the system instability caused by renewable energy variations. The proposed strategy is analyzed theoretically and validated in MATLAB/Simulink simulation and laboratory experiments. The results demonstrate the advantages of the proposed method over conventional approaches under various scenarios.

Original languageEnglish
Article number9198101
Pages (from-to)9630-9640
Number of pages11
JournalIEEE Transactions on Industrial Electronics
Volume68
Issue number10
DOIs
Publication statusPublished - Oct 2021

Keywords

  • Adaptive droop
  • adaptive virtual impedance
  • instability
  • large droop gains
  • microgrid
  • power deficiency

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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