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Electromagnetic interference (EMI) is mainly caused by the periodic valve switching in HVdc converter stations. This EMI can result in high-frequency conducted and radiative interference toward the adjacent communication, computer equipment, carrier system, and radio stations. Therefore, a wideband model of a converter system is necessary to predict the characteristics of the EMI source. Methods of modeling are proposed, and the equivalent circuits of the main equipment in ultra-HVdc (UHVDC), including valve section, converter transformer, smoothing reactor, filters, and so on, are developed in this paper. The whole wideband model is simulated by PSCAD/EMTDC. Based on this model, the characteristics of the conducted EMI under normal operation conditions are calculated. Ground-level electric field strength and magnetic field strength in and around a UHVDC converter station are calculated. For validity, a comparison between the simulated and the measured data is conducted. [ABSTRACT FROM AUTHOR]

The corridor of the high-voltage direct current transmission lines in China is very complex and there may be buildings near the lines. The conductivity of the building material may influence the electric field in the building. In this paper, based on the upstream FEM, a method is proposed to solve the coupled problem of the ion flow field in the air and the current field in the building model. The numerical results coincide with the analytic results and measurement results. The electric field in and on the building model is analyzed considering different conductivities. [ABSTRACT FROM PUBLISHER]

A modified method based on the optimized charge simulation method (CSM) is used to predict the corona onset voltage and electric field when the space charges due to the corona are considered. Based on the streamer model of corona discharge, space charges generated near the conductors are predicted. In order to calculate the electric field at the conductor surface, space charges are replaced by some equivalent line charges near the conductor. Because of the existence of space charges, the corona onset electric field is changed a little. After a simplified model of actual power transmission lines is introduced with the help of rough coefficient, the corona onset voltage and corona onset electric field are calculated for different types of conductors finally. [ABSTRACT FROM PUBLISHER]