基于全局滑模时滞的电力系统混沌振荡控制

Power system chaotic oscillation control based on global sliding mode time delay

电力系统易受扰动影响,在一定扰动条件下会进入混沌状态。通过分岔图和李雅普诺夫指数谱分析了扰动Pe与Pk单独作用与共同作用时对电力系统的影响,当Pe与Pk单独作用时,系统状态均随着扰动的增加由周期态过渡到混沌态,当Pe与Pk共同作用时,系统状态均随着扰动的增加由混沌态过渡到周期态再过渡到混沌态。设计了一种全局滑模时滞控制策略,时滞控制采用延时反馈环节,即误差信号中采用上个采样周期的采样值与此时的采样值来对不确定系统项与扰动项进行估计,但由于延时环节存在时滞误差,导致系统收敛速度较慢且扰动抑制能力较差。为此,将时滞控制与全局滑模控制相结合,并设计具有快速收敛特性的时滞补偿项,提高系统收敛速度与抗扰动能力,并且可以抑制上界未知的外部扰动。仿真结果表明,相较于时滞控制,所设计的全局滑模时滞控制收敛速度更快,超调量更小,在系统遭受周期扰动与阶跃扰动时仍能保证收敛。

It is easy for a power system to be affected by disturbance and it will enter a chaotic state under certain disturbance conditions.A bifurcation diagram and the Lyapunov exponential spectrum are used to analyze the influence of perturbation Pe and Pk on the power system when they act alone or together.When Pe and Pk act alone,the system states transition from the periodic state to a chaotic state with the increase of perturbation.When Pe and Pk act together,with the increase of the disturbance,the system states transition from the chaotic state to a periodic state and then back to a chaotic state.This paper designs a kind of global sliding mode control with time-delay strategy.The time delay control uses a delay feedback loop,namely the error signal using the sampling value of the sampling period and the sampling value of uncertain systems are estimated with the disturbance.However,because of the delay link lag error,this results in slow convergence speed and lower ability to reject disturbance.For this reason,the time delay control is combined with global sliding mode control,and a time delay compensation term with fast convergence is designed to improve the convergence speed and anti-disturbance ability of the system.This also suppresses the external disturbance whose upper bound is unknown.The simulation results show that compared with the time-delay control,the proposed global sliding mode time-delay control has faster convergence speed and less overshooting,and can still guarantee convergence when the system is subjected to periodic and step disturbance.