溪洛渡直流送端系统中PSS对次同步振荡的影响及应对措施

为了探究溪洛渡直流送端系统曾出现次同步振荡现象的原因并提出相应的改进措施，首先采用复转矩系数法、测试信号法分析了威信电厂发电机组在投入电力系统稳定器(PSS)前后的阻尼特性。分析结果表明由于直流输电的接入削弱了电网次同步阻尼，PSS的投入引发了系统次同步振荡。在分析现有问题的基础上，通过对电磁功率偏差反馈型和加速功率偏差反馈型PSS进行改进，提出了新型可切换式PSS。最后基于PSCAD/EMTDC仿真平台，验证了新型可切换式PSS可提高系统次同步阻尼特性并对次同步振荡有良好的抑制效果。

Impact of PSS on subsynchronous oscillation in Xiluodu DC sending end system and its countermeasures

In order to explore the reason of subsynchronous oscillation in Xiluodu DC sending end system and to propose corresponding improvement measures, firstly, by means of complex torque coefficient approach and the test signal method, the damping characteristics of Weixin power plant generators before and after PSS(Power System Stabilizer) integration are analyzed. Research results show that since the subsynchronous damping of the grid is weakened by the access of HVDC, and the input of PSS causes subsynchronous oscillation of the system. Then on the basis of analyzing the existing problems, a novel switchable PSS is proposed by the improvement of electromagnetic power deviation-based type PSS and accelerating power deviation-based type PSS. Finally, based on the PSCAD/EMTDC simulation platform, it is verified that the novel switchable PSS can not only improve the subsynchronous damping but also suppress the subsynchronous oscillation.