Inversion Method for Equivalent Thermal Conductivity of Bushing Capacitive Screen Based on Physics-Informed Neural Network
Lü Yuhui1, Liu Yadong1, Yan Yingjie1, Cai Jianfeng2, Huang Xiaobo2
1. School of Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 China;
2. Huizhou Power Supply Bureau Guangdong Power Grid Co. Ltd Huizhou 516000 China
Dry-type resin-impregnated paper (RIP) bushings have been widely applied in converter transformers and high-voltage direct-current (HVDC) systems owing to their oil-free insulation, strong moisture resistance, and low maintenance requirements. However, the absence of internal oil circulation causes heat to accumulate within the bushing core, which increases the thermal stress on the composite insulation structure and accelerates insulation aging. Temperature-field modeling of RIP bushing are performed by finite element methods (FEM) and the results of temperature distribution simulations are highly dependent on the selected model parameters. Because the thermal conductivity of the multilayer capacitive screen cannot be directly characterized using conventional measurement techniques, determining its equivalent thermal properties remains a major challenge for accurate thermal simulation and temperature-rise analysis. This study addresses this problem by proposing a data-efficient inversion method, identifying the thermal conductivity of the capacitive screen using sparse temperature information.
A physics-informed neural network (PINN) based inversion framework was developed to estimate the equivalent radial and axial thermal conductivities of the capacitive screen. A two-dimensional axisymmetric heat-conduction model was constructed using domain partitioning to represent the conductor, capacitive core, bottom flange and outer sheath. The multilayer screen region was homogenized into an anisotropic medium, enabling the model to retain directional thermal-transfer characteristics while reducing geometric and computational complexity. The steady-state heat-conduction partial differential equation (PDE) and interface conduction conditions across different materials were embedded directly into the total loss function of PINN method. This formulation restricts the solution space to physically consistent states and enables the network to infer internal parameters directly from sparse temperature measurements. To enhance PINN’s training stability, an adaptive gradient-balancing strategy was employed, which dynamically regulated the weights of the PDE, boundary, and observation losses and strengthen convergence robustness.
To evaluate the effectiveness of the proposed PINN method, a 110 kV RIP bushing temperature-rise platform was established. Under the consistency of other variables such as ambient temperature and humidity, steady-state temperature data of four different operating current levels (60%In, 80%In, In, and 110%In) at several typical positions were collected, including conductor rod, the connecting seat, bottom flange and the outer sheath. After reversion, the identified thermal conductivity parameters were imported into a FEM model for independent verification. The simulations replicated the measured temperature-rise characteristics with deviations held within ±2 K across all monitored points, indicating that the inferred parameters accurately reflect the thermal behavior of the composite capacitive screen. These results demonstrate that the proposed PINN-based inversion framework provides a reliable and data-efficient means for identifying effective thermal properties in multilayer insulation systems, offering a practical tool for improving thermal-field modeling and enhancing the design and evaluation of power-equipment insulation structures.
The results show that the proposed PINN inversion framework can effectively recover the anisotropic equivalent thermal conductivity of multilayer composite insulation from sparse obtainable temperature data. The method relies on only a small set of training data and retains high physical consistency and interpretability, making it possible to infer otherwise unmeasurable thermal conductivity from discrete temperature measurements. The framework can be extended to other power equipment, including transformer windings, reactor insulation cylinders, and dielectric components in gas-insulated switchgear (GIS). The proposed approach provides an effective pathway for improving thermal-field modeling accuracy, refining temperature-rise evaluation, and supporting future digital-twin applications for the thermal management of power equipment.
吕昱辉, 刘亚东, 严英杰, 蔡建峰, 黄晓波. 基于物理信息神经网络的套管电容芯体等效热导率反演方法[J]. 电工技术学报, 2026, 41(19): 6753-6766.
Lü Yuhui, Liu Yadong, Yan Yingjie, Cai Jianfeng, Huang Xiaobo. Inversion Method for Equivalent Thermal Conductivity of Bushing Capacitive Screen Based on Physics-Informed Neural Network. Transactions of China Electrotechnical Society, 2026, 41(19): 6753-6766.
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