EMI analysis of hybrid HVDC breaker

Hybrid high voltage direct current (HVDC) breaker is one of the most important equipment in DC transmission networks. As it is known, the hybrid breaker consists of large numbers of power electronics devices and the nonlinear elements, so, during the fault occurrence there are many transients voltages and currents with sharp rate of (dv/dt, di/dt) resulting from switch-on and switch-off of transistors which may cause electromagnetic interference (EMI). The EMI not only affects hybrid breaker self-electronic system, but also affects the neighboring communication and control devices. In this paper the sources of EMI have been identified and the snubber circuit conducted EMI characteristics have been simulated under normal operation and fault occurrence using PSCAD/EMTDC software.