Electromagnetic environment near HVDC thyristor valves

Thyristor electronic units of HVDC converters are commonly installed very closely to the thyristors. Hence they are exposed to relatively severe electromagnetic interference (EMI) produced during valve operation. The electronic units are working at the thyristor level with the essential functions of firing, protecting and monitoring the thyristors. These functions must not be influenced during converter operation. In order to ensure a sufficient immunity of the units, the electromagnetic stress acting on them must be known. Corresponding field calculations were performed by numerical simulations taking into account the detailed valve construction as well as the spatial valve arrangement. From the results, corresponding impulse field immunity tests can be derived