Study on operation characteristics and stability evaluation method at sending-end of DC transmission system

For the situation that many Ultra-HVDC projects can not reach the maximum transmission capacity in the beginning of operation. Considering more Ultra-HVDC projects put into operation recently, this paper analyzed key facts limiting transmission capability at the sending-end of Ultra-HVDC from static stability, voltage fluctuation and AC-DC coupling characteristics. Furthermore, based on short-circuit ratio which is usually in receiving-end of DC, analyzes the relationship between short-circuit ratio of sending-end of DC and maximum transmission capability, and the critical short-circuit ratio maintaining stable operation of system at sending-end of DC transmission is given.