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Seismic Performance Evaluation of HV Circuit Breakers in Transmission Substations and Application of Base Isolation to Improve their Behavior

Zare Feizabadi, Ali | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52847 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Bakhshi, Ali
  7. Abstract:
  8. The main goal of this study is to evaluate the seismic performance of HV circuit breakers of power substations and optimize their seismic behavior using base isolation systems. Iran is in a region with high seismicity and has experienced severe earthquakes in recent decades that have resulted in serious damages to critical infrastructures. These include power substations that are important during and even after an earthquake in providing electricity for homes, industries, amenities, emergency facilities, public transportation and more. The seismic performance of HV circuit breakers, which is an important equipment for power substations, has not been satisfactory in past earthquakes and has suffered many damages. The base isolation system is one of the most effective methods for seismic retrofitting of structural and non-structural equipment. Using this system in HV circuit breakers can lead to a significant reduction in damages to the equipment and financial losses. This study investigates the seismic behavior of HV circuit breakers and their weaknesses in earthquakes using numerical analysis and finally compares the performance of the proposed base isolation systems to present the best isolation systems to improve their seismic performance.Time history analyzes on finite element model of circuit breaker indicate that the high stresses created at the base of the porcelain column during the earthquake result in its failure and collapse. The results show that the use of seismic isolation system leads to a significant reduction of bending moment at the base of the porcelain column of the device as well as top acceleration. The bending moment at the base of the porcelain column of the circuit breaker with friction-pendulum, lead-core rubber and high damping rubber isolators is reduced by up to 80, 75 and 70 percent, respectively. The maximum acceleration of the circuit breaker with friction-pendulum and lead-core rubber isolators has been reduced by about 60 percent. Using of high damping rubber isolators also reduces the maximum acceleration of the circuit breaker by 55 percent. High damping rubber isolators have a relatively poor performance in reducing device responses compared with other isolators. The use of friction-pendulum isolators with a radius of curvature of 1.5 m and friction coefficient of 0.1 has a significant effect on reducing the seismic responses of the HV circuit breaker. A lead rubber isolator with all specifications is also designed and proposed
  9. Keywords:
  10. Seismic Isolation ; Seismic Performance ; Transmission Substation ; Base Isolation ; Electrical Substation Equipment ; High Voltage Circuit Breakers

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