基于VSC-HVDC的统一附加阻尼最优控制方法

相比于传统发电机的电力系统稳定器（PSS），柔性直流输电（VSC-HVDC）系统可以有效控制区域间的低频振荡。考虑到VSC-HVDC系统有功无功均能对交流系统进行独立控制，提出了基于有功无功双环控制的统一低频振荡控制器，并基于VSC的有功功率和无功功率控制分别设计附加控制回路来增加控制器的控制效果。首先采用最小二乘旋转不变（TLS-ESPRIT）辨识方法获得系统小信号模型和振荡特性，然后基于辨识出的模型，利用基于最优控制理论对控制器进行设计，并将最终所设计控制器分别附加于有功控制回路与无功控制回路。PSCAD的仿真结果表明，相比于常规的有功附加控制器，所提统一控制方法能达到更好的控制效果，并能保证鲁棒性。

Optimal Control Method of Unified Additional Damping Based on VSC-HVDC

Compared with the traditional PSS added to AC generators， the VSC-HVDC system can control the inter-area low frequency oscillation effectively. Considering that both active power and reactive power can be controlled by VSC-HVDC independently，a unified low frequency oscillation controller is proposed based on active power and reactive power control loop. The supplementary controllers of VSC are both designed and added to active and reactive control loop. Firstly， the TLS-ESPRIT algorithm is used for identification to obtain the small signal model and the damping characteristic of the system. Then LQR method is used for controller design. Finally， the designed controller is attached to the active power and reactive power control loop respectively. Based on the simulations of PSCAD software，the results prove the effectiveness and robustness of the designed controller compared to the traditional one.