DC-link voltage regulation of inverters to enhance microgrid stability during network contingencies

M. A. Hossain*, H. R. Pota, A. M. O. Haruni, M. J. Hossain

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Equal power-rating inverters operating with different power set-points in either an islanded or grid-connected mode may lead to inter-unit circulating power caused by a large mismatch between power generation and demand during network contingencies (faults on the heavy load side or unintentional islanding). This circulating power may violate the dc-link voltage limit and, as a result, the protection scheme may shut down the inverter and reduce the microgrids reliability. This paper proposes a regulator for controlling the dc-link voltage of the microgrid's inverter during a period of circulating power. It includes a discharging resistor with a series-connected switch across the dc-link capacitor which is turned on through a control algorithm if the dc-link voltage exceeds its pre-defined limit. Case studies of parallel-connected inverters are conducted and their stability assessed through a small-signal analysis. In addition, a realistic microgrid is designed as a low-voltage (LV) network and tested to verify the concept and regulator actions presented. The simulation results validate the effectiveness of the proposed regulator during network contingencies.

Original languageEnglish
Pages (from-to)233-244
Number of pages12
JournalElectric Power Systems Research
Volume147
DOIs
Publication statusPublished - 1 Jun 2017

Keywords

  • DC-link voltage
  • islanded microgrid
  • droop control
  • supervisory controller

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