The valve-side bushing of a converter transformer is a critical component in ultra-high-voltage direct current (UHVDC) systems, making its monitoring through digital twin technology highly significant. However, the complex structure and spatio-temporal nonlinearity of the bushing result in a large computational demand for its digital twin model, which requires an effective order reduction algorithm. This paper proposes a Spatio-temporal Non-uniformity Proper Orthogonal Decomposition (SN-POD) algorithm considering the inhomogeneity of space and time consumption to meet the reduced-order computational requirements of UHV valve-side bushings. This proposed method reduces the calculation time to 10% of the full-order simulation model while controlling the error range of the key research area less than 0.1%. The test results show that this method has good robustness, calculation speed, and accuracy. This research can significantly enhance the computational efficiency of digital twin modeling for valve-side bushings and provide a technical foundation for constructing digital twin models for UHV valve-side bushings.

There is a temperature gradient distribution inside the capacitor core, and classical theoretical formulas cannot quantitatively describe the influence of the nonlinear characteristics of the insulation material of the capacitor core on the electric field strength distribution. It is urgent to introduce nonlinear characteristics of the insulation medium into the optimization design of the valve side bushing, fully considering the electric thermal coupling mechanism to improve its operational reliability. To address the above issues, based on the in-depth research results of key physical mechanisms, this paper proposes a model-driven complete digital twin modeling approach for valve side casing and constructing an industrial software for the digital twin. Firstly, the characteristics of the digital twin modeling of valve side casing based on the mechanism model are systematically analyzed, and a complete structural specification for the digital twin model of valve side casing is investigated. Then, the design of the complete digital twin model of the valve side casing is designed and the full process interaction and connectivity of the digital twin modeling of the valve side casing is realized. Finally, the proposed method provides a reference for the digital twin modeling of high-value power equipment.