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DGA Gases related to the Aging of Power Transformers for Asset Management

  • Kweon, Dongjin (Transmission & Substation Laboratory, Korea Electric Power Corporation Research Institute) ;
  • Kim, Yonghyun (Transmission & Substation Laboratory, Korea Electric Power Corporation Research Institute) ;
  • Park, Taesik (Department of Electrical and Control Engineering, Mokpo National University) ;
  • Kwak, Nohong (Department of Electrical and Control Engineering, Mokpo National University) ;
  • Hur, Yongho (Gangwon Regional Headquarter, Korea Electric Power Corporation)
  • Received : 2017.06.15
  • Accepted : 2017.08.03
  • Published : 2018.01.01

Abstract

Life management technology is required as the failure risk of aged power transformers increases. Asset management technology is developed to evaluate the remaining life, establish the replacement strategies, and decide the optimal investment based on the reliability and economy of power transformers. The remaining life assessment uses data such as installation, operation, maintenance, refurbishment, and failure of power transformers. The optimal investment also uses data such as maintenance, outage, and social costs. To develop the asset management system for power transformers, determining the degradation parameters related to the aging of power transformers and evaluating the condition of power transformers using these parameters are important. In this study, since 1983, 110,000 Dissolved Gas Analysis (DGA) data have been analyzed to determine the degradation parameters related to the aging of power transformers. The alarm rates of combustible gases ($H_2$, $C_2H_2$, $C_2H_4$, $CH_4$, and $C_2H_6$), TCG, CO, and $CO_2$ were analyzed. The end of life and failure rate (bathtub curve) of power transformers were also calculated based on the failure data from 1981 to 2014. The DGA gases related to discharge, overheating, and insulation degradation were determined based on alarm and failure rates. $C_2H_2$, $C_2H_6$, and $CO_2$ were discharge, oxidation, and insulation degradation parameters related to the aging of power transformers.

Keywords

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Fig. 1. Cumulative number of power transformers andDGA sampling

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Fig. 2. Distribution of DGA results

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Fig. 3. Distribution of transformer with DGA results

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Fig. 4. DGA alarm rate related to the age of powertransformers

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Fig. 5. Weibull distribution of power transformers

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Fig. 6. Failure rate of power transformers

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Fig. 7. Alarm rate of H2 & C2H2 due to the aging oftransformers

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Fig. 8. Alarm rate of C2H4 & CH4 due to the aging oftransformers

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Fig. 9. Alarm rate of C2H6 & TCG due to the aging oftransformers

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Fig. 10. Transformers with the GOST type oil preservationsystem

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Fig. 11. DGA alarm as oil conservation systems

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Fig. 12. DGA alarm gases of transformers with the GOSTtype oil preservation system

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Fig. 13. Alarm rate of CO & CO2 due to the aging oftransformers

Table 1. DP in paper from three aged and four failed transformers

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References

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