Fault Current Analysis in Integrated HVDC Network

Abstract

Today the world is interconnected by various means to fulfil its requirements related to newlineelectrical energy. The most common method for electrical energy transportation is to newlineconnect two points, especially if they are located at considerable distance, via High newlineVoltage DC (HVDC) Link. An HVDC Link has become quite feasible nowadays due to newlinethe diminishing cost of power converters and improvements in semiconductor newlinemanufacturing technology. HVDC systems have many advantages like low conduction newlineloss, less conductor requirement, relatively higher power transfer capability per unit newlineconductor length, better power control, better power quality transfer compared to HVAC newlinesystems. However, all these advantages of HVDC system comes at the cost of fault newlinerelated stability. newlineHVAC systems have a strong factor safety from the fault which is inherent to the nature newlineof alternating current. A 50Hz Alternating current crosses zero current line 100 times in newlinea second and it is very easy to operate a fast circuit breaker near zero current line to break newlinethe circuit. This process cannot be done with Direct Current (DC) circuit systems because newlinethe current never truly goes to zero. Depending up on the configuration of HVDC newlinenetwork the fault current varies a lot. Hence, a proper protection system is achievable newlineonly when parameters of the possible fault current are estimated properly using scientific newlinemethods. newlineIn this work various topologies of HVDC networks have been compared over multiple newlinetimes with variations in polarity of the terminal, return path of the circuit between two newlineterminals, grounding schemes implemented at each terminal and network connection newlineamong multiple terminals to observe the fault current profile. A simulated environment newlinehas been created for the testing of these topologies with modelling of various components newlinelike DCCB, underground transmission line, modular voltage source converter has been newlinemodelled in the view of modern state of the art technologies. The results find out the best newlinedesign for fault.