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Fault Diagnosis in Power Systems by Wide-area Measurement System

Salehi Dobakhshari, Ahmad | 2014

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 46167 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ranjbar, Ali Mohammad
  7. Abstract:
  8. A power transmission system includes transmission lines that are interconnected for economic and security reasons. Power systems are often prone to faults at the transmission level, since transmission lines are spread over vast geographical areas. Being the most serious events in power systems, blackouts are often initiated by a fault and a sequence of events afterward leads to partial or complete power outage. In this condition, fault diagnosis is the first step for power system restoration. In this research work, a new approach utilizing impedance-based fault location is introduced for fault diagnosis. By developing wide-area measurements in the context of smart grids, accurate measurements of bus voltages and line currents (synchronized or unsynchronized) are available at various substations in the transmission grid. The proposed approach in this thesis solves the fault diagnosis problem by fitting the measured wide-area signals on the expected signals, which are functions of the fault location. The proposed wide-area fault-location method locates the fault irrespective of fault type and resistance, thanks to modeling the fault as a current source. The problem is solved in various cases of availability of different measurements (voltage/current) and different types of measurements (synchronized or unsynchronized). Each measured voltage or current signal is written as a function of fault location based on the bus impedance matrix. Next, the Newton-Raphson method is used to find the fault location based on the partial derivatives of the modified bus impedance matrix elements with respect to fault location. For unsynchronized measurements, the measurement functions are modified so that the need for estimating the synchronizing angles of measurements is obviated. Electromagnetic transient simulations for 9-bus and 22-bus test systems demonstrate that the proposed method is capable of employing different sunchronized or unsynchronized voltage or current measurements for fault diagnosis.

  9. Keywords:
  10. Fault Detection ; Transmission Lines ; Fault Location ; Wide Area Measurement System ; Bus Impedance Matrix

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