针对交直流系统区间低频振荡问题,尤其是广域测量系统引入的时滞影响问题,利用递归最小二乘法在线辨识区间振荡主导模态,在直流附加控制抑制低频振荡机理的基础上,通过在线计算利用交流联络线功率信号进行阻尼控制的滞后相位与时变时滞造成低频振荡模态信号的滞后相位,将时域信号转化为二维旋转坐标体系中的向量信号,经过参考坐标体系的角度旋转,分别进行阻尼与时滞滞后相角的自适应补偿,结合增益放大,通过时域反变换后可得到最终补偿后的直流附加控制量。8机36节点系统仿真表明,所提设计方法能够消除时变时滞的影响,有效阻尼系统低频振荡,并且具有鲁棒性,适合在线应用。
In allusion to inter-area low-frequency oscillation occurred in AC-DC power transmission system, especially to the time delay caused by wide-area measurement system, using recursive least squares (RLS), the online identification of dominant modal of inter-area oscillation is implemented, and on the basis of suppressing low-frequency oscillation by adding supplementary control of HVDC, through the online calculation of the lagging phase caused by utilizing power signal of AC tie line transmission line for damping control and the lagging phase of low-frequency oscillation signal due to the time-varying delay, the time-domain signals are transformed into vector signals in the two dimensional rotating coordinate system, then by means of angle rotated in reference coordinate system the adaptive compensation for lagging phase due to damping control and the adaptive compensation for lagging phase due to time-varying delay are carried out respectively. Combining with gain amplification, after the inverse transformation in time-domain the post-final compensation DC supplementary controlled quantity can be obtained. Simulation results of a 8-machine 36-bus system show that the proposed method can eliminate the affect of time-varying delay and effectively damp low-frequency oscillation in power grid, besides, the proposed method is of robustness, so it is suitable for online application.