基于同伦变换的VSC-HVDC分散协调鲁棒阻尼控制器设计

Design of Decentralized Robust Damping Controller for VSC-HVDC Transmission System Based on Homotopic Transformation

针对含柔性直流的区域互联电力系统低频振荡,提出一种基于同伦变换的有功、无功分散协调控制方法。首先,通过数字子空间状态空间系统辨识算法辨识出系统多输入多输出(multiple input multiple output,MIMO)状态空间模型,并对系统进行振荡模态分析。其次,基于线性矩阵不等式鲁棒控制理论,设计出集中MIMO附加鲁棒控制器。最后,应用同伦变换将集中MIMO鲁棒控制器转化为分块对角化的结构,从而得到多个低阶单输入单输出鲁棒控制器。仿真验证表明,该文所设计的有功、无功相协调的分散鲁棒控制器能有效抑制低频振荡,控制器阶数低,无耦合,鲁棒稳定性强,在严重故障情况下能充分利用基于电压源换流器的直流输电的有功和无功调制能力,并且在信号丢失时能保持较好的阻尼性能。

For low frequency oscillations of multi-area interconnected power systems linked with a voltage source converter based high voltage direct current transmission（VSC-HVDC） system, this paper proposed a control coordination method based on homotopic transformation to coordinate the active and reactive power damping controllers. Firstly, a Numerical algorithm for subspace state space system identification（N4SID） was carried out to get the system＇s multiple input multiple output（MIMO） State Space modal, and then analysis the system＇s oscillation modes. Secondly, a centralized MIMO supplementary controller was designed using linear matrix inequality（LMI） based robust control theory. Lastly, a set of low-order single input single output（SISO） decentralized controllers can be obtained through deforming the centralized MIMO controller into a block-diagonal structure using homotopic transformation. The simulation results show that the decentralized SISO robust controllers which coordinate active and reactive power have many advantages such as low order, no cross-coupling, stronger robustness and good performance of suppressing low frequency oscillation. Besides, decentralized SISO controllers can take full advantage of the VSC-HVDC＇s modulation capacity of active and reactive power in the case of serious fault, decentralized SISO controllers still keep good performance in the condition of input signal loss.