Considerations on energy absorption of HVDC circuit breakers

This article deals with possible solutions for energy absorption in HVDC transmission systems. Depending on the converter topology high current slopes can appear in case of DC short circuits. Besides the handling of high currents itself, HVDC Circuits Breakers have to decrease the energy stored in line inductances in order to interrupt. Although different breaker concepts have been proposed, energy absorption is yet generally based on high voltage surge arresters. Isolation and over-voltage protection level have to be well adapted to expected surges and metal oxide surge arresters fit this problem. However, validating the maximum switching action count of those breakers, lifetime considerations of ZnO varistors have to be studied critically. In this paper a comparison on dimensioning needs and voltage stresses regarding an HVDC environment shall be carried out for existing solutions and furthermore a new proposal using resistors in addition to freewheeling diodes shall be made. This is verified by simulations with MATLAB Simulink.