Chaos Analysis And Control Of Power Systems Based On Complex Disturbances

With the continuous growth of the national economy,the demand for social electricity also rises rapidly.It is an inevitable direction of development for the power system in large units,large power grid,extra high voltage and crossed regional interconnection.It is obvious for the power system about multivariablity,strong nonlinearity and strong coupling,which has become a nonlinear dynamic system with great complexity.To ensure the stable operation of the system,it is basic to understand the dynamic behavior of the system.In addition,a proper control strategy must be designed to suppress chaotic oscillations in the system.In this paper,two nonlinear models of power system are established considering alternator and load respectively.On the basis of the dynamic characteristics of the system,the control strategy is proposed to control chaotic oscillations in power system.The main research contents are given as follows:Firstly,the model of interconnected power system is built.The dynamic properties of the interconnected power system are investigated through bifurcation diagram,Lyapunov exponent spectrum,phase diagram and Poincare maps.The range of parameters corresponding to different motion states of the system are divided accurately.The sensitivity of the system to the amplitude of disturbance is deeply studied when the disturbance frequency is different.Secondly,a four order power system model with photovoltaic link is established.The influence of the parameters of the generator end and the load end on the stability of the system is studied.Considering the motion pattern of the system when the system is subjected to electromagnetic power disturbance and load disturbance,and the dynamic behavior of the system under the influence of disturbance amplitude and frequency of disturbance is observed.The sensitivity of the system to the perturbations is analysised through contrasting bifurcation diagram.Finally,the control strategy of two systems is proposed to suppress the chaotic motion.The effect of control methods is contrasted between sign function and relay characteristic function.It is found that the buffeting of the sliding mode variable structure control based on the relay characteristic function is smaller than sign function.An adaptive robust control strategy is proposed in the light of the four order system.The adaptive term and the robust term are added to the control law.The experimental results show that the power angle of the system converges quickly to the target orbit and the control curve is smooth.The phenomenon of tremor is obviously weaked.