Protection Systems and Earthing Schemes for Microgrids: Main Aspects and Fault Analysis

Filipe Bandeiras, Mário Gomes
  • Corresponding author
  • Instituto Politécnico de Tomar (IPT), Tomar, Portugal
  • Smart Cities Research Center (Ci2-IPT), Tomar, Portugal
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, Paulo Coelho
  • Instituto Politécnico de Tomar (IPT), Tomar, Portugal
  • Smart Cities Research Center (Ci2-IPT), Tomar, Portugal
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, José Fernandes and Carlos Moreira
  • Instituto de Engenharia de Sistemas e Computadores-Tecnologia e Ciência (INESC TEC), Porto, Portugal
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The content of this paper aims to assist in the development and implementation of microgrids by addressing the challenges and possible solutions for their protection systems. Therefore, an overview of some protection methods available in the literature that can be implemented to ensure a safe and reliable microgrid operation is presented, including the most common protection devices and earthing schemes that can be adopted in low voltage distribution systems. In addition, this paper also presents a brief fault analysis of internal faults at three different locations in an industrial microgrid with centralized and decentralized deployment of energy sources, as well as a short-circuit analysis of symmetric and asymmetric faults at these faulty locations. An approximate method based on the calculation of the equivalent impedance seen from the fault location is used to determine the fault currents. This study is made to observe how microgrids with different configurations perform in the event of internal faults.

It is demonstrated in this work that setting a specific protection strategy to allow the microgrid to operate effectively during both operation modes can be problematic and expensive in most situations. With this in mind, additional effort is necessary to engineer and implement new protection approaches that can overcome the limitations of protection systems in future microgrids.

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IJEEPS publishes significant research and scholarship related to latest and up-and-coming developments in power systems. The mandate of the journal is to assemble high quality papers from the recent research and development efforts in new technologies and techniques for generation, transmission, distribution and utilization of electric power.