THE RESEARCH ON THE AFFECTION OF THE QINGHAI-TIBET HVDC TRANSMISSION SYSTEM UPON OPERATING CHARACTERISTIC OF THE LINE PROTECTION IN QING-HAI AC ELECTRICAL POWER SYSTEM

摘要

Based on ±400 kV Qinghai-Tibet HVDC transmission system,the paper build a closed loop simulation system used HyperSim system and HVDC control protection device.Used this system,the paper researched the impedance characteristics and harmonic constitute of Qinghai A.C.electrical power system in different faults,analyzed the proportion of harmonic component in voltage and electric while various faults at different point,and studied the impaction of directional protection,differential protection and distance protection for the AC transmission line according to the characteristics of protection operation.