基于平衡理论的双端柔性直流输电系统降阶小信号建模

为了提高直流输电系统小扰动稳定性分析计算效率,建立了直流输电系统小信号降阶模型。文章以双端直流输电系统为研究对象,首先建立了双端柔性直流输电系统小信号模型,然后基于平衡理论将系统状态量按Hankel奇异值数目排序进行阶数选择,经过矩阵变换实现小信号模型的降阶。通过计算全阶系统和降阶系统的主导特征根变化轨迹,验证了降阶系统与全阶系统具有一致的小扰动稳定性。仿真结果表明,降阶前后具有相似的动态响应,验证了降阶模型的准确性。在复杂网络环境下,基于平衡理论的降阶方法不仅减小模型复杂度、提高了计算效率,还可对系统的稳定性进行预判。

Reduced-Order Small-Signal Model of Double-Terminal Flexible DC Transmission System Applying Equilibrium Theory

In order to improve the calculation efficiency of small-signal stability analysis of DC transmission system, a small-signal reduced-order model of DC transmission system is established. Taking the two-terminal flexible DC transmission system as the research object, this paper firstly establishes the small-signal model of the two-terminal flexible DC system, and then selects the order of the system state variables according to the number of Hankel singular values on the basis of the equilibrium theory, and realizes the reduction of the small-signal model through matrix transformation. By calculating the dominant eigenvalue trajectories of the full-order system and the reduced-order system, it is verified that the reduced-order system and the full-order system have the same small-disturbance stability. The simulation results show that there is a similar dynamic response before and after the order reduction, which verifies the accuracy of the reduced-order model. In the face of complex networks, the order reduction method based on equilibrium theory can not only reduce the complexity of the model and improve the computational efficiency, but also predict the stability of the system.