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Overhead Line Dynamic Thermal Rating Using Fuzzy Method and its Effect on Power System Reliability

Shaker Ardakani, Hamid | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40068 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fotuhi Firuzabad, Mahmoud
  7. Abstract:
  8. In recent years, because of power system restructuring and load growth, much of transmission lines are reaching to their maximum capacity. Therefore, it is so essential to upgrade existing transmission system. However, constructing new lines is a very expensive and time consuming method. Dynamic thermal rating of overhead line is an alternative solution for upgrading transmission system capacity. In this method, allowable current capability of line in the next duration is calculated according to the environmental conditions. A method should be developed to perfectly model these environmental changes. Fuzzy method is a powerful tool that models uncertainties and measurement errors in a simple way while forecasting will be entered in calculations too. Furthermore, changes of wind speed and direction that play an important role in the thermal rating of lines can be modeled easily by fuzzy theorem. Therefore, using this method is recommended in this thesis. Fuzzy numbers are used to model dynamic thermal rating of overhead lines and then they are compared by their crisp results. The results show that if proper membership functions and good forecasting methods are used, the fuzzy model can result in better results than the crisp model. Furthermore, using this method we can lessen sampling without losing sensible accuracy. The proposed fuzzy model for dynamic rating of transmission lines is applied to the NCUC problem and to composite power system reliability evaluation. The results presented show that the proposed method decreases system total cost (in the case of the NCUC problem) and reliability indices (in the case of composite power system reliability evaluation) of bulk power system.

  9. Keywords:
  10. Capacity Enhancement ; Reliability ; Fuzzy Set Theory ; Dynamic Thermal Rating ; Real-Time Rating ; Allowable Line Current Capability ; Steady State Heat Balance

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