Influence of Metal Shield Materials on Electromagnetic Field and Losses in End Region of Synchronous Condenser

A synchronous condenser (SC) used in an ultrahigh-voltage direct current system often operates under overexcitation and underexcitation conditions, which can dramatically change the field in the end region. A metal shield plays an important role in the end region of SC, and different metal shield materials have an effect on the distribution of the magnetic flux and loss. The selection of the metal shield is, therefore, a key factor that should be carefully considered in the design of SC. For a 300-Mvar SC with different metal shields, this article presents the mathematical models of the three-dimensional (3-D) transient electromagnetic field in the end region. The flux densities and losses of the end structural components are compared under the rated excitation and loss of excitation. From the detailed performance evaluations by the 3-D finite-element analysis, the variation laws of the flux densities at the key points and the losses of the end structural components along with the conductivity of the metal shield are revealed. The regions of the maximum loss in the end structural components are obtained. The results provide the theoretical basis for the improvement of the loss distribution in the end region of the SC.