Analytical approach to dimension transient currents in asymmetric VSC monopole

Sammanfattning: As an important part of robust design of an HVDC station, all HVDC equipmentshould stay safe and sound during steady state mode as well as transientcondition. In order to have a proper dimensioning for the equipment,maximum transient stress and current should be derived and calculated byperforming transient current studies.The transient current studies should be done twice during the project process,tender and delivery phase. Based on the nature of these two phases, simplifiedformulas derived from Thevenin circuit is used during tender work whilecomprehensive HVDC models and simulation in PSCAD is used in deliveryphase of a project.The scope of the Exam work is to derive formulas for the dimensioning transientcurrents for asymmetric VSC monopoles and create a calculation tool. In orderto have a better platform for future developments such as optimizeddimensioning of equipment vs transient current, the result is a calculation toolin Matlab with the collected formulas derived from Thevenin voltage andimpedances of the equivalent circuit for decisive faults cases.