Browsing by Author "Etxegarai, A."
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Item Analysis of loss of life of dry-type WTSU transformers in offshore wind farms(2020) Etxegarai, A.; Valverde, V.; Eguia, P.; Perea, E.; DIGITAL ENERGYCurrently, dry-type transformers are commonly installed as wind turbine step-up (WTSU) transformers, especially in offshore wind farms. Due to their low flammability and resistance to moisture, their performance is optimal in offshore platforms. Nonetheless, their thermal-electrical degradation must be carefully considered given the special wind and weather conditions in marine environments. The present paper studies the thermal aging of dry-type WTSU transformers in offshore wind farms considering the most thermally stressed location i.e. the winding hot-spot. The estimation of the transformer lifetime consumption introduced in this work can be applied in the framework of digital twins for diagnostic and prognostic monitoring purposes The thermal degradation study is based on a typical offshore load profile and includes the analysis of the impact of several transformer characteristics and operating conditions. As a result of the analysis, it can be concluded that lower temperature insulations, forced air cooling systems, a lower mean winding temperature rise and cool ambient temperatures lead to decreased loss of life values. Also, the present work suggests the suitability of considering thermal degradation studies as an optimal sizing factor for offshore WTSU given the low ambient temperatures in marine environment and the low capacity factors.Item Impact of a resistive superconductive fault current limiter in a multi-terminal HVDC grid(Institute of Electrical and Electronics Engineers Inc., 2018-06-08) Saldana, G.; Etxegarai, A.; Larruskain, D. M.; Iturregi, A.; Apinaniz, S.; POWER ELECTRONICS AND SYSTEM EQUIPMENTThe relevance of multi-terminal HVDC grids is expected to increase in next years. However, there are still several technical, economical and legal limitations that interfere with the construction of those multi-terminal links. One of the main technical obstacles is the handling of DC fault currents, because the interruption of DC currents in HVDC systems is nowadays a challenge. Among other proposals, the application of Superconducting Fault Current Limiters (SFCLs) combined with a mechanical Circuit Breaker (CB) solves technically that issue, according to the analysis and simulation results presented in this paper.Item Study of Useful Life of Dry-Type WTSU Transformers(2020-06) Etxegarai, A.; Valverde, V.; Eguia, P.; Perea, E.; DIGITAL ENERGYDry-type transformers are rapidly becoming popular as wind turbine step-up (WTSU) transformers, especially in offshore wind farms. Cast resin transformers are not flammable and are also resistant to moisture. However, their thermalelectrical degradation must be carefully analysed given the special conditions of wind farm installations. The present paper studies the remaining useful life (RUL) calculation of dry-type WTSU transformers based on the most thermally stressed location i.e. the winding hot-spot. The estimation of the loss of life of the transformer can be used for diagnostic and prognostic monitoring purposes in the framework of digital twins. The methodology is then applied to a typical WTSU load profile and the impact of several transformer characteristics and operating conditions are compared to the reference case.