Measurement and modeling of valve components in HVDC converter stations

Electromagnetic interference (EMI) is generated by the periodic switching of the valves in HVDC converter station. This EMI can cause high frequency radiative interference and conducted interference to the adjacent communication, computer equipment and carrier system operations. So a high-frequency model of converter valves is necessary to predict the characteristic of the EMI source. The modeling method is based on the impedance measurement of thyristor, snubber circuits and saturable reactor and the frequency range is from 100 kHz to 50 MHz. Vector fitting is used to approximate the rational functions and impedance synthesis theory is applied to provide equivalent circuits suitable to EMTP and PSCAD. These models can be used to analyze the characteristic of EMI sources in converter stations and have a guide on immunity and screening design. For validity, a comparison between the simulated and measured is conducted.