Micro-Grid Protection in Presence of Inverter Based Distributed Generation

Zarei, Fariborz | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46570 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Parniani, Mostafa
  7. Abstract:
  8. In this study, control and protection of low voltage microgrids have been analyzed. Studied microgrid takes the advantages of inverter based distributed generation. One of the most important issues in inverter based microgrids is the control of its distributed generation. Since, the low voltage networks have single phase loads and many imbalances, these imbalances can affect the control of IBDGs (inverter based distributed generations). This issue in the islanded mode of operation is the most important, because in this mode of operation, IBDGs control the network voltage and frequency.
    In this thesis, the different control strategies of IBDGs are reviewed, and then modified to address the imbalances and faults. The proposed controllers, independent of load dynamics and imbalances, establish the voltage and frequency.
    Another challenge facing the microgrids and active distribution networks is the protection problems. There is two types of protection issues. At first issue, with the arrival of synchronous machine based DGs, short circuit levels in the network increases and lack of coordination between protective devices will be occurred. The second issue occurred in the inverter based microgrids that operated in islanded mode of operation. This is due to limited output current of this type of DGs, thus the conventional protection devices cannot operate with acceptable performance.
    To solve the first problem, in this study, FCL (fault current limiter) is used. In the proposed method, the network protection and their settings might be without any changes, and coordination between protective devices shall be maintained. The prominent features of proposed method are its simplicity and low cost.
    To solve the second problem, a comprehensive protection strategy is proposed. This protection strategy maintains its efficiency, independent of microgrid operation mode. The proposed method isolates the fault, so that it allows the operation of downstream DGs. Also, this method does not depend on functional mode, and does not need to data processing center and use of adaptive methods
  9. Keywords:
  10. Fault Current Limiter ; Digital Relay ; Microgrid ; Distributed Generation ; Distributed Generation ; Microgrid Protection ; Microgrid Control

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