多通道高压直流广域改进射影控制器设计

Design of multi-channel wide area modified projective controller for HVDC transmission system

为了对交直流互联系统含有的低频振荡和次同步振荡同时进行抑制,给出了一种改进的射影控制方法。通过总体最小二乘-旋转不变算法辨识出交直流输电系统送端孤岛运行方式下的振荡模态和降阶后的模型,运用带通滤波器将不同振荡频率的模态分解为多个通道,根据射影控制理论并做出改进,设计出多通道直流附加阻尼控制器。该控制器能够降低各种振荡模式间的相互影响,兼顾了控制器的阶数和鲁棒性。考虑到广域信号采集和传输过程中存在时滞问题,根据辨识结果并设计出了系统的相位补偿器。利用该方法对PSCAD/EMTDC中的某直流孤岛运行下的模型进行建模仿真,并与无附加阻尼控制下的系统进行比较分析。结果表明多通道射影控制器可以同时抑制低频振荡和次同步振荡,具有较好的鲁棒性;同时设计出的相位补偿器可以有效地解决系统的时滞问题。

To suppress the low frequency oscillation and sub-synchronous oscillation in the interconnected system at the same time, a kind of modified projective control method is given. Oscillation modals and the reduced-order controller of the AC/DC transmission system operating in island mode are identified by total least squares-estimation on signal parameters via rotational invariance techniques. Taking advantage of the band-pass filters to decompose the different oscillation frequencies into different channels, then according to the modified projective control theory, multi-channel projective controllers are designed. The controllers can reduce the mutual influence among the different oscillation models, also, the order and robustness of controllers are taken into consideration. Considering the time delay problems when the wide area signals are in the course of gathering and transferring, which can cause the control results worse, the phase compensation controllers are designed based on the identification results of the system. Taking advantage of this method to carry on the modelling and simulation in one DC model under the island operating, then comparison and analyses are done with the system without supplementary damping controller. The results validate that the multi-channel projective controller can suppress the low frequency and sub-synchronous oscillation at the same time, also, good robustness is verified; the phase compensation controllers designed can solve the time delay problems effectively.