Research on the electromagnetic disturbance source considering the effect of valve tower stray parameters

As the electromagnetic disturbance (EMD) in valve hall is the leading disturbance source in HVDC converter station. With the valve tower stray parameters taken into account, the frequency spectrum characteristic of the electromagnetic disturbance in the valve hall is investigated. To determine the stray parameters of the valve tower structure, all the conductors in valve hall are included in the electromagnetic model established by using the finite element simulator ANSYS. Based on the resultant stray parameters, the wide-frequency-band valve circuit model applicable to the electrical transient simulator PSCAD/EMTDC is established. The electromagnetic disturbance is analyzed for the two transient processes that the converter valve is conducted and cut,. Hence the general effect of the stray parameters on the electromagnetic disturbance in converter station is obtained from the frequency spectrum. The research indicates that, although the stray parameters may reduce the conducted disturbance level in converter station, unfortunately the possibility of high frequency oscillation is increased on the other hand.