Current transformer failure analysis using ATPEMTP during circuit breaker switching on capacitor bank

Name: Warunee Srisongkram.

keyword: ATP/EMTP.

LCSH: Current transformers (Instrument transformer)

LCSH: Failure analysis (Engineering)

Abstract: The purpose of this dissertation consists of two major objectives. The first purpose is to investigate the transient phenomenon of electrical stresses caused by capacitor bank switching. Because, the transient cause damage to the HV equipment in the substation. The second purpose is to select a proper rating of the HV equipment based on the procedure of insulation coordination. The system is modeled by using an Electromagnetic Transients Program-Alternative Transients Program (ATP/EMTP) platform. A selected case study is a conventional air-insulated 115 kV substation in Thailand, where the damages on the HV equipment during the capacitor bank switching occured. The comprehensive model for the electrical transient simulation is designed and is created by using actual and derived data from a real physical dimension of the component in HV substation. The simulated results are challenged by comparison between the results from theoretical computations according to international standard and the result from an on-site measurement. The comparable results used to verify the accuracy of the developed model. The comparison shows satisfy result. The final results showed the phenomenon of the electrical transient, especially during energization and de-energization of capacitor banks in the system substation. This electric trasient leads to high magnitude of inrush current and high transient overvoltage that could probably damage switching devices and another HV equipment in substation. Then the developed model is used to investigate the problem of the damaged current transformer in a HV substation as well as circuit breaker insulation affecting of restriking voltage to degeneration. The results showed that the severe transient over voltage causes the damage of the current transformer insulation and the degeneration of circuit breaker insulation as well. For in sulation coordination, the proper voltage level is selected by using the known electrical stresses. This is obtained from a simulation using the developed model to determine the withstand voltage strength based on the procedure described in the insulation coordination standard IEC 60071 part 1 and 2 as well as IEEE 1313 part 1 and part 2. Finally, the simulated model and the procedure for insulation coordination is applied to study the effects of the electrical transient on other HV substation in power system. Furthermore, this prototype model is rapidly applied to investigate the switching overvoltage in critical HV substations. Several cases of switching overvoltage investigation with variable parameters is quickly and effectively performed through the developed model providing time-saving, and avoiding on-site measurement in terms of operative safety and system interruption. The insulation coordination is used as a guideline for selecting the optimum voltage rating of new HV equipment in a new or renovated/refurbished substation.

King Mongkut's University of Technology North Bangkok. Central Library

Address: BANGKOK

Email: library@kmutnb.ac.th

Name: Thanapong Suwanasri

Role: Dissert Advisor.

Email : thanapong.s@tggs.kmutnb.ac.th

Created: 2018

Modified: 2563-09-15

Issued: 2020-09-15

วิทยานิพนธ์/Thesis

application/pdf

eng

DegreeName: Doctor of Engineering

Level: Doctoral Degree

Descipline: Software Systems Engineering (English Program)

Grantor: King Mongkut's University of Technology North Bangkok

©copyrights King Mongkut's University of Technology North Bangkok

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