In many countries worldwide, the energy demand is growing faster than the transmission capacity. However, due to environmental constrains, social concerns and financial costs, the construction of new power transmission lines is an arduous task. In addition, power transmission systems are often loaded close to their nominal values. Therefore, improving power transmission system efficiency and reliability is a matter of concern. This work deals with a 400 kV, 3000 A, 50 Hz extra-high-voltage expansion substation connector used to connect two substation bus bars of 150 mm diameter each. This substation connector has four aluminum wires which provide the conductive path between both bus bars. Preliminary tests showed an unequal current distribution through the wires which was mainly attributed to the proximity effect. A three-dimensional finite elements method approach was applied to improve the design and evaluate the electromagnetic and thermal behavior of both the original and improved versions of the connector. Experimental tests made under laboratory conditions have validated the accuracy of the simulation method presented in this paper, which may be a valuable tool to assist the design process of substation connectors, therefore allowing improving both the thermal performance and reliability of the redesigned connectors.
This paper shows the capabilities of applying the three-dimensional finite element method (3D-FEM) for designing complex-shaped substation connectors to operate at 765 kVRMS AC. To check this methodology, it was analyzed the feasibility of upgrading a 400 kVRMS substation connector to operate at 765 kVRMS. However, both experimental and simulation results conducted according to the ANSI/NEMA CC 1-2009 standard concluded that although it passed the visual corona test, to ensure a wide safety margin it was desirable an improvement of the electrical behavior of such connector. It was shown that FEM results allowed detecting the peak stress points of the connector regarding the electrical stress thus allowing applying a corrective action. Then, two possible solutions were analyzed, i.e. the use of corona shields and the redesign of the connector assisted by 3D-FEM simulations. Results presented in this work show that both approaches have an excellent behavior in reducing the electric field strength on the connector surface. However, to make the final decision, the production cost of both alternatives was analyzed, thus favoring the redesign option. Next, the redesigned version of the substation connector was manufactured and tested. Experimental results conducted in a high voltage laboratory verified the effectiveness of the methodology and the potential of the proposed system to act as an advanced design tool for optimizing the behavior of complex-shaped substation connectors. Thus, this system allows assisting efficiently the design process while permitting constraining the economic costs