With the incident of the bipole trip caused by a monopole trip in the on-site commissioning of Yunnan-Guangdong high-voltage direct current （HVDC） islanded operation on May 26

2013 as an example

the response characteristics of the HVDC reactive power control and generator excitation system after the monopole trip are analyzed. It is pointed out that the anti-regulation with power system stabilizer (PSS) has significantly worsened the overvoltage problem of the islanding system

and inadequate adaptability of the HVDC reactive power control for the frequency and voltage changes after a large disturbance is the direct cause of the bipole trip. The existing overvoltage controls of the islanded HVDC sending system are mainly concentrated on the converter station side

without fully utilizing the voltage control capabilities of generators. In order to better solve the temporary overvoltage problem after HVDC trips

further study on the solution to the PSS anti-regulation problem is required to bring the role of the excitation regulator into full play. The technological ideas of wide-area PSS and high voltage side voltage control are proposed and verified by simulation.