Research On A Novel Topology Of Current Limiting Hybrid HVDC Circuit Breaker

Power generation from renewable energy supplies is a need of the future power grid in order to address the rising problem of climate change and to accommodate the growing electricity demand.And the majority of renewable energy supplies are located far away from load centers.On the other hand,the High Voltage Direct Current(HVDC)power transmission system is a suitable candidate for the transmission of power from distant generation plants.Power system protection is one of the crucial steps in the development of modern HVDC systems because of the rapid rise in DC-short circuit current due to the lower inductance of HVDC cables.Whereas,the hybrid HVDC circuit breaker(CB)is one of the most suitable candidates for the protection of modern HVDC grid network.For the advancement of hybrid HVDC CB,the current limiting reactor is the main features to be considered since insertion of DC reactor in fault current flow path causes a reduction in fault current rising rate and prolongs the time to reach current breaking peak value which ultimately gives more time for selective fault protection.In this paper,a novel topology for the current limiting hybrid HVDC CB is proposed which provides a low loss operation during steady-state along with selective fault protection for an HVDC network by using the current limiting mode before employing the current breaking operation.In the proposed topology,before implementing the current limiting mode a current commutation mode is established which adds a small reactance to the fault current flow which in turn advantageous in case the fault is temporary as it will reduce the time for re-closure operation and then the current limiting mode is implemented in such a way that the overall inductance is much increased and the number of switching devices is also increased to interrupt the peak fault current.Multiple temporary fault operations with different fault durations are carried out and results are verified on the simulation model.For the validation of the feasibility of the proposed topology,a Power System Computer-Aided Design(PSCAD)model is created and analyzed using the results.