The power supply for Jinguan-Guizhong HVDC sending-end system is provided by two run-off-river hydropower plants. In the dry season

due to insufficient water

power can not meet the requirements of short-circuit capacity for HVDC safe operation. The long-term low-load operation of power plants leads to serious safety hazards in the power plant and plant infrastructure

threatening the safe operation of the power plant and HVDC. According to the design requirements and simulation

we analyzed the effects of short-circuit capacity shortage on the system stability

AC over-voltage

and low-order resonance characteristics

and optimized the safe operating boundary conditions and HVDC transmission power setting of Jinguan-Guizhong HVDC. In order to ensure the stable operation of the system after the HVDC project jumped into island operation

we proposed a technical scheme of active blocking strategy as follows: to first cut off all the AC filters in the converter station

and then block the bipolar HVDC emergency. The optimization scheme reduces the start-up requirements of DC system power plants. The minimum total number of power plants has been reduced from 4 to 2. The power of HVDC is set to 600 MW in dry season. Therefore

not only the requirements of safe and stable operation mode of Jinguan-Guizhong HVDC in interconnection and island can be met

but also the flexibility of operation mode arrangement of HVDC and sending-end system power plants can be enhanced.