Influence of Magnetic shield on Electromagnetic Field and Losses in End Region of Synchronous Condenser

Abstract

Synchronous condenser (SC) can operate at the over- and under-excitations and provide the dynamic reactive power for the convertor station of the Ultra High Voltage Direct Current (UHVDC). The different operation conditions of the SC result in the significant variation of the magnetic field in the end region. A magnetic shield plays an important role in the end region of SC. The structure of the magnetic shield directly affects the distribution of the magnetic field and loss in the end region. The reasonable selection of magnetic shield is therefore a key factor that should be carefully considered in the design of SC. For a 300-MVar SC with different thickness magnetic shields, this paper 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 3-D finite element analysis, the variation laws of the flux densities and loss densities of the end structural components along with the thickness of the magnetic shield are revealed. The regions of the maximum loss affected by the structure of the magnetic shield in the end structural components are obtained. The results provide the theoretic basis for the improvement of the loss distribution in the end region of the SC.