Multifield Calculation and Analysis of Excitation Winding Interturn Short Circuit Fault in Turbo-Generator

Abstract

Excitation winding interturn short circuit (EWISC) is a common fault in turbo-generators. Once the fault occurs, if not handled in time, it will result in significant security risks to the power system. Using the multifield characteristics of fault generators for a comprehensive diagnosis can make the diagnostic results more accurate and credible. In this paper, taking a TA-1100-78 type, two pole pairs turbo-generator as the research object, the two-dimensional finite element electromagnetic model of stator/rotor and the three-dimensional finite element heat transfer model of rotor were established. The electromagnetic field, temperature field, and stress field of the generator were simulated and analyzed. At the same time, the air gap magnetic field, three-dimensional temperature field, and stress field distribution of the rotor were calculated for EWISC faults in different fault degrees and positions. The results showed that the EWISC fault weakened the air gap magnetic field and caused unbalanced electromagnetic distribution. At the same time, it caused a distortion of the rotor temperature field, resulting in an unbalanced distribution of the temperature field. The stress field was affected by the distortion of temperature field, and the local thermal stress increased but did not exceed the yield limit of the material. Restorable elastic deformation occurred when the rotor was heated, which caused the thermal bending of the rotor. The method adopted in this paper can provide a reference for the calculation of multiphysical field after a generator fault. It is also pointed out that the thermal unbalance influence should not be neglected in the study of generator vibration characteristics.

Study on the suppression effect of variable hydrogen parameters on the temperature rise of the turbo‐generator rotor under deep peak regulation

“…Under deep peak regulation conditions, the excitation current of the turbine generator frequently changes over a wide range, resulting in severe temperature fluctuations in the rotor windings. The thermal stretching effect induces axial displacement of the rotor windings, which may not only damage the slot insulations and interturn insulations to form grounding or interturn short circuit faults but also blocks the rotor windings ventilation, exacerbate local temperature rise and cause thermal bending and severe vibration of the rotor [3][4][5][6]. In recent years, frequent faults have occurred in the machines under deep peak regulation conditions, resulting in damage to the rotor components, as shown in Figure 1.…”

Calculation and Analysis of Rotor Thermal Static Field for Inter-Turn Short Circuit of Large Hydro-Generator Excitation Winding

“…In reference [13], the influence of rotor radial ventilation ducts number on temperature distribution of rotor excitation winding and fluid flow state between two poles of a fully air-cooled hydro-generator was calculated. Reference [14] calculated the temperature field and thermal stress of excitation winding inter-turn short circuit faults in turbo-generators. The temperature field and thermal stress were analyzed to provide characteristic parameters for inter-turn short circuit fault diagnosis of turbo-generators.…”