混合多端直流输电系统附加控制器设计

针对包含混合多端直流的交直流互联系统区间低频振荡现象，提出一种基于射影控制原理的控制器降阶设计方法。搭建混合三端直流输电系统，确定控制策略，利用总体最小二乘-旋转不变技术辨识出系统开环模型。得出系统状态反馈增益矩阵，保留闭环系统主导特征值，基于射影控制原理设计低阶输出反馈控制器，并基于线性矩阵不等式设计 阻尼控制器进行比较。测试系统的特征值分析和时域仿真结果表明：射影控制器不仅阶数低，而且具有更好的阻尼特性和鲁棒性。

Design of additional controller for hybrid multi-terminal DC transmission system

As to the low frequency oscillation of AC/DC parallel power system which contains hybrid multi-terminal DC, a reduced-order controller design method based on the principle of projective control is introduced. Three-terminal hybrid DC transmission system is built, and the control strategy is determined. The model of the system is identified by the least square-estimation method via rotational technique (TLS-ESPRIT), a state feedback gain matrix is obtained, and dominant eigenvalue of the closed-loop system is retained, then a low-order output feedback controller is designed by projective control, and a damping controller based on linear matrix inequalities is compared. Finally, the results of the eigenvalue analysis and digital simulation of the testing system show that projective controller has lower order, stronger robustness and better damping characteristics.