An Improved Test Method to Investigate the Power Transformer Winding Buckling Hoop Stress

Power transformers play a pivotal role in power grids, yet they are invariably exposed to short-circuit impacts. Precise assessment of the winding mechanical strength is crucial for ensuring power grid security. Nevertheless, traditional short-circuit tests face significant challenges in identifying critical stability states due to the high cost and destructive nature, which impedes the accurate assessment of winding strength. To address this issue, this paper proposes an improved buckling hoop stress investigation (IBHSI) test method that focuses on the inner windings. The novelty of this approach lies in its utilization of the non-equivalent force characteristics exhibited by winding disks along the height. Departing from conventional practices, it enables the accurate determination of the winding buckling hoop stress with a limited number of transformer samples and test times. Initially, a representative transformer is meticulously selected. By preliminarily estimating the winding's critical withstand current, a series of short-circuit tests as described in this paper are implemented. Afterward, the transformer is disassembled to identify the location where gradual deformation occurs. Through a secondary simulation focused on this specific position, the buckling hoop stress can be precisely calculated. The IBHSI method not only significantly enhances the verification ability of short-circuit withstand capacity but also provides a novel and more precise means of assessing winding stability, effectively compensating for the inadequacies of traditional testing methods.