基于可观测与可控度的直流输电次同步振荡阻尼控制研究

Research on HVDC subsynchronous damping control based on observability and controllability degree

汽轮发电机组轴系在次同步频率范围内往往存在多个扭振模态。目前对高压直流输电引起的多模态次同步振荡尚缺乏行之有效的抑制策略,系统中多次出现应用次同步振荡阻尼控制器后轴系依然存在明显振荡的现象。应用状态空间法对轴系机械系统进行分析,建立了次同步振荡模态的可观测度与可控度的概念。在设计次同步振荡阻尼控制器时,基于次同步振荡的可控与可观测度进行参数优化。PSCAD/EMTDC的时域仿真结果表明,传统的次同步振荡阻尼控制器对于可观测与可控度较低的振荡模态抑制效果较差,而所提出的基于可观测与可控度的次同步振荡阻尼控制器对于所有模式的次同步振荡均能有效抑制。研究成果对于抑制高压直流引起的多模态次同步振荡具有重要参考价值。

In subsynchronous frequency range, usually there are multiple modes of torsional vibration for turbine generator shaft. At present, the effective damping strategy is deficient for multi-mode subsynchronous oscillation induced by high voltage direct current. In power system, the phenomena have happened several times that obvious shaft oscillations still exist after subsynchronous damping controller has been applied. In this paper, state space method is used to analyze shaft mechanical system, and the concept of mode observability and controllability degree of subsynchronous oscillation is established. In the design of subsynchronous damping controller, the parameters are optimized based on observability and controllability degree of subsynchronous oscillation modes. Simulation results of PSCAD/EMTDC indicate that traditional subsynchronous damping controller is not very effective for the oscillation mode with relative low observability and controllability degree and the subsynchronous damping controller based on observability and controllability degree proposed is very effective for all subsynchronous oscillations in different modes. The product of this paper has important reference value for damping multi-modes subsynchronous oscillation induced by high voltage direct current.