中文摘要：

建立了采用电压倾斜控制的多端柔性直流输电系统（VSC-MTDC）的小信号模型。文中首先设计了电压倾斜控制器,能够实现多端直流系统遭受扰动时,换流站间不需要通信可以自动恢复稳定运行。然后文中采用线性化动态方程描述了整个多端直流系统,包括换流器、控制系统（电压倾斜控制,内/外环控制及锁相环）,直流线路及交流系统。通过将所建模型与电磁暂态模型进行时域下的详细比对,验证小信号模型的正确性。最后,基于小信号模型得到多端系统的根轨迹曲线,并通过判断主导极点在坐标系中的位置,分析电压倾斜控制参数对稳定性的影响。

英文摘要：

The small signal model of VSC-MTDC with voltage droop control is built in this paper. First, the voltage droop control is designed, and the MTDC system utilizing this method can be recovered without communication between converters when disturbance occurred. Then, the linearized dynamic equations are derived to describe the whole MTDC system, including converter, control system（voltage droop control, inner/outer loop control and PLL）, DC transmission line and ac system. The proposed small signal model is also verified by comparing with EMT model in time domain. At last, the root locus is obtained with the proposed model, and the effect of parameters of voltage droop control on the stability of MTDC system is analyzed by determining the location of the domain poles