VSC-HVDC的控制方式对交直流混联系统小干扰稳定性的影响

Impact of VSC-HVDC Control Strategy on Small Signal Stability of Hybrid AC/DC Power System

首先阐述了VSC-HVDC的控制原理和双闭环控制器的基本构成,然后利用模块化建模方法,并结合状态空间法,给出了含VSC-HVDC的复杂交直流混联系统小干扰建模的一般方法,且不需要解析地推导全系统小干扰模型A,B,c,D矩阵中的每个元素,大大简化了含VSC-HVDC的交直流混联系统的小干扰建模。接着利用所建模型,在相同运行条件下,重点分析了定无功功率和定交流电压2种不同控制方式对全系统小干扰稳定性的影响,结果表明采用定无功功率控制比采用定交流电压控制直流系统具有更好的阻尼系统振荡的性能,但这2种控制方式对发电机相关模态的影响不大,最后用时域仿真验证所得结论。

First this paper expounds the control principle of VSC-HVDC system and the basic structure of double closed loop controller. Based on the modular modeling method, combined with state space method, then the paper proposes the general method for modeling the small signal stability of hybrid AC/DC system with VSC-HVDC, no longer needing to deduce analytically the elements in matrix A, B, C, D for the small signal model of hybrid AC/DC system, and greatly simplifying the modeling process. By using the proposed model, the paper focuses on the impact analysis of constant reactive power and constant AC voltage on the small signal stability of the hybrid AC/DC system. The results show that the damping of VSC-HVDC system is greatly affected by VSC control modes. The constant reactive power control is better the constant AC voltage control. But these two control modes have an insignificant effect on the AC system. The above results are validated via time domain simulation.