Transient thermal modelling of substation connectors by means of dimensionality reduction

Abstract

-This paper proposes a simple, fast and accurate simulation approach based on one-dimensional reduction and the application of the finite difference method (FDM) to determine the temperatures rise in substation connectors. The method discretizes the studied three-dimensional geometry in a finite number of one-dimensional elements or regions in which the energy rate balance is calculated. Although a onedimensional reduction is applied, to ensure the accuracy of the proposed transient method, it takes into account the three-dimensional geometry of the analyzed system to determine for all analyzed elements and at each time step different parameters such as the incremental resistance of each element or the convective coefficient. The proposed approach allows fulfilling both accuracy and low computational burden criteria, providing similar accuracy than the three-dimensional finite element method but with much lower computational requirements. Experimental results conducted in a high-current laboratory validate the accuracy and effectiveness of the proposed method and its usefulness to design substation connectors and other power devices and components with an optimal thermal behavior. . The use of 3D-FEM simulation tools often requires the use of costly licenses and the implication of specialized engineers to carry out tedious and time-consuming tasks associated to the preparation of 3D geometries, generation of the 3D mesh, or settling of boundary conditions among others. Therefore the development of accurate fast models [12] which can be based on model reduction techniques [13] and are highly appealing to overcome the abovementioned drawbacks. Different approaches have been applied to reduce the computational burden in complex 3D problems. For example in [14] a co-simulation strategy combining 1D finite difference and 3D finite volume codes are applied. In [15] a1D analytical model for simulating the response of piezoelectric transformers was compared against 3D-FEM simulations. In [16] a 1D finite difference approach to model mass conservation in ducts of an internal combustion engine was studied. Cerfontaine et al. [17] proposed a 1D-finite element formulation to model the grouting and field temperatures of borehole heat exchangers. This paper proposes a one-dimensional fast method based on nodal equations and finite differences formulation to accurately predict the temperature evolution in substation connectors during the standard temperature rise test. This is a multiphysics electromagnetic-thermal problem since the main heat source is the Joule loss due to the electric current whose time-profile is known, although there is a minor contribution due to the induced eddy currents. The proposed method discretizes the analyzed domain in finite one-dimensional regions in which the energy rate balance due to the flow of heat is calculated. To accurately predict the temperature profile along the connector and the surrounding conductors, the proposed transient model takes into account the three-dimensional ge...

Feasibility analysis of reduced‐scale visual corona tests in high‐voltage laboratories

“…8b. 0.9863 SSE (sum of squares due to error) 2 4.269 RMSE (root mean squared error) 2 0.8435 1 95% confidence bounds 2 Goodness of fit statistics…”

“…Substation connectors interconnect the different elements of the facility [1], and thus, a suitable and optimized design is highly desirable. Substation connectors must pass different standard tests to ensure a suitable performance (thermal, mechanical, corrosion, or electromagnetic) under nominal operating conditions [2]. Before undergoing compulsory standard tests, the new designed connectors are extensively validated in the laboratory to ensure appropriate performance and reliability, especially when mathematical models are not available.…”

Review of Electrical Connectors for Underwater Applications

“…Many studies analyze the effects of one property on another, for example by combining high-temperature cycles and high-power transfer [52], [53], or by modeling thermal effects due to electrical loads [54], [55], or with thermo-mechanical studies [56]. Some other articles study the influence of electrical and thermal properties on a connector's lifetime and aging capacities [57], [58].…”

Fast electro‐thermal simulation of short‐circuit tests

“…To determine the transient conditions during the short-circuit test, the electro-thermal energy balance is calculated in each node, similarly as done in a previous research of the authors of this work [18] to simulate temperature rise tests. To increase accuracy and reduce drastically the computational burden, the one-dimensional model retains key information of the three-dimensional geometry from the CAD of the test object to determine the temperature distribution along the conductor and the connector.…”

“…Although the proposed model deals with the inherent singularities of short-circuit tests and bimetallic connectors for low-and medium-voltage applications, it is based on the approach presented in [18] which deals with bolted aluminum substation connectors for high-voltage applications. The analysis of the shortcircuit behavior presents different particularities and challenges with respect to the study of the temperature rise test presented in [18], such as the short duration in which the adiabatic approximation applies during the heating phase, the transient nature of the current waveform during the initial stage of the short-circuit, or the wider and sudden temperature rise because of the extreme thermal stress during the short-circuit condition.…”