Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Electrical Power and Machines

In this thesis, arc interrupting in HVDC circuit breaker and the effects of different controlled and uncontrolled parameters on the arc interruption time are investigated and reported. The electrical arc is considered as a non-linear phenomenon; the black box arc model is used in this thesis to simulate the non-linear arc conductance depending on Mayr and Cassie dynamic arc equations. The key challenge that faces arc interrupting in HVDC circuit breaker is the absence of natural current zero crossing. Hence, there is a need to use additional circuits connected in parallel with HVDC circuit breaker to generate artificial current zero crossing during the fault clearing period, in order to help the HVDC CB to be able to interrupt the electrical arc. DC fault test bed modeling was carried out by Matlab/Simulink software is used to evaluate the capability to protect a 500kV HVDC overhead transmission line. Line to ground fault is simulated to present the capability of HVDC CB to interrupt the electrical arc current, in addition to study the effects of different parameters on arc interruption time.The final results demonstrate the suitability of the applied model to interrupt the electrical arc current. Furthermore it presents the most proper value of different controlled parameters that can be applied to achieve the appropriate arcing time. Moreover it presents the influences of uncontrolled parameters on the arcing time

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