Thermodynamic modelling of buried transformer substations for dynamic loading capability assessment considering underground heat accumulative effect. (October 2020)

• Record Type: Journal Article
• Authors: Zhou, Bin; Xu, Xiaolin; Or, Siu Wing; Li, Canbing; Wu, Qiuwei; Zhang, Cong; Li, Wenfang
• Is Part Of: International journal of electrical power & energy systems. Volume 121(2020)
• Publication Date: 2020-10
• Subjects: Dynamic loading capability -- Hot-spot temperature -- Heat accumulative effect -- Thermal modelling -- Transformer; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2020.106153
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: A thermal circuit model for fully buried transformers is proposed to calculate the winding HST. The underground heat accumulative effect is considered with soil thermal dissipation. Dynamic assessment of loading capability is presented for transformer lifetime extension. The finite element analysis is implemented for verification and tuning of the proposed model. Abstract: The lifetime cycle and secured service of buried transformers are constrained by their thermal insulation and loading conditions. This paper proposes an extended thermal circuit model for direct-buried transformer substations to dynamically evaluate the transformer loading capability. In the proposed model, the underground thermal interactions and energy balances among heat generation, transfer and storage in the transformer substation are represented with nonlinear thermal resistances and capacitances based on thermal-electrical analogies, and then hot-spot temperature (HST) dynamics can be captured from the nodal analysis on this R-C thermal equivalent circuit. Furthermore, the underground thermal accumulative effect is investigated for dynamic loading capability assessment considering the combined impact of heat accumulation in the surrounding soil caused by fluctuating transformer loads during prior operating periods. Finally, the finite element analysis with measured data is implemented for parameter tuning and model verification of the proposed thermodynamic model, and numerical simulations confirm the improvements of the proposed model for the transformer life extension and load management.