Synthesis of wide frequency model of HVDC valve elements

High voltage direct current (HVDC) converter station generates radio frequency (RF) electromagnetic noise by the periodic turn-on and turn-off of the valve. This noise can affect the performance of adjacent communication, control and computer equipments and can interfere with carrier system operation. In order to calculate and predict the RF noise produced by the valve ignition, it is essential to develop accurate models of valve equipments (thyristor, snubber circuit, equalized capacitance, saturation reactor) over a broad frequency range. After measuring the frequency dependent impedance of the elements, the wide frequency model of valve elements can be set up with rational approximation and Brune synthesis method. At last by comparing the numerical results with EMTP ensure the efficiency and accuracy of the model.