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Presenting Practical Solutions to Mitigate the Effects of Fault Induced Delayed Voltage Recovery (FIDVR) Phenomenon on the Special Protection Systems of Power Network

Rezaei Moghadam, Salar | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51976 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Vakilian, Mehdi; Hajipoor, Ehsan
  7. Abstract:
  8. Fault Induced delayed voltage Recovery (FIDVR) is a phenomenon that occurs due to the behavior of motor loads such as A/C loads during voltage drop due to fault occurrence in the transmission, sub-transmission and distribution network. The electric motors used in air conditioning systems have a constant torque and inertia, and may therefore be stalled due to voltage drops And after the fault clearing, by dragging high reactive power and a current of 5 or 6 times the rated current, it leads to a continued voltage drop and a slowdown in the voltage recovery process. After a while, the thermal protection devices of the motors can cause significant load losses and subsequently increase the network voltage due to the dynamics of the tap changers and the reactive power compensator. Consequently, in the absence of control and monitoring of the FIDVR phenomenon, there will be a possibility of a wide black out and the collapse of the voltage due to the branching out of the network equipment. In this thesis, by first examining a number of common A/Cs in the tropical region of southern Iran and comparing the results of their modeling with the results of the experimental modeling in other utilities reports, around the world; a comprehensive model for modeling the behavior of A/C loads from the power grid point of view is developed and presented. In order to find the power system network vulnerabilities in terms of voltage recovery, a screening method with two evaluation indicators has been proposed. This grid screening method is very effective when due to existence of a large number of buses checking every individual network node in terms of FIDVR, is not feasible. Finally, to increase the speed of voltage recovery at vulnerable nodes of the network, the method of “Impedance Deviation based Load Shedding” is proposed. In this method, while determining the effective buses in the FIDVR, the amounts and priority of the loads for load shedding necessary to reduce the effects of FIDVR are determined. The results have been tested on IEEE 14 and 39 bus test systems, which verifies the correct performance of the load model for FIDVR phenomenon study, as well as the high efficiency of the screening and load shedding methods employed for “voltage recovery improvement” after FIDVR occurrence
  9. Keywords:
  10. Voltage Recovery ; Fault Induced Delayed Voltage Recovery ; Load Modeling ; Air Conditioning ; Screening Method ; Under Voltage Load Shedding

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