Impact of Negative Sequence Current on Electromagnetic Torque in Nuclear Power and Large Size Turbo‐Generators

Distinguished from the former researchers, this article aims at researching the effect of the stator fundamental negative sequence current in turbo‐generators on the electromagnetic torque both from theoretical analysis and finite element simulation. Firstly, based on three sequence component analysis, coordinate system transform and interaction analysis of magneto‐motive force vectors, the concrete expression of direct component of the electromagnetic torque is given, and the concrete expression of second harmonic electromagnetic torque is presented by a new vectorial approach proposed in this article. Further, the impact of the stator fundamental negative sequence current on the electromagnetic torque has been discussed in details by the new approach proposed in this article. In order to prove the correctness of the analytical analysis by the new approach proposed in this article, two turbo‐generators have been taken as examples, and their finite element simulation models have been built up and tested through experimental data. Moreover, the simulation result verifies the effectiveness of the analytical expression and analytic analysis proposed in this article. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.