Analysis And Control Of Bifurcation Chaos In Power System

The development of human society is inseparable from the process of electrification,and the most direct source of power is the power generated by the power grid system with the power system as the main body.With the progress of science and technology and the continuous improvement of people’s life,the demand for power is increasing day by day,which makes the scale of power grid grow in explosive mode,but the rapid development also brings uncertain security risks to the power grid.Stable and reliable electric energy has become an important research direction of modern power technology.The power quality is measured by voltage,frequency and harmonic.Among them,voltage is the most direct factor affecting the production and life of human society.Voltage stability is one of the key technical indicators to measure the safety of modern power system.As an important branch of nonlinear system theory,bifurcation and chaos theory,it has been widely used in various projects,and has made a lot of research results in many fields.It is possible to study the voltage stability of power system based on Bifurcation and chaos theory.Bifurcation is a qualitative change of the system caused by external disturbance or its own parameters,which causes voltage oscillation and collapse of power system,and chaos in a specific situation.In order to ensure the stable operation of power system,it is necessary to eliminate the possible bifurcation phenomenon and the subsequent failure behaviors such as low frequency oscillation and voltage collapse.Therefore,it is of great significance to analyze and study the voltage instability of power system from the perspective of bifurcation and chaos,and design corresponding controller.Based on the theory of bifurcation and chaos,this paper analyzes the conditions of bifurcation and chaos in power system and the voltage characteristics in chaotic state.On this basis,the controller is designed to achieve voltage stability of power system.The main work includes the following parts:Firstly,considering the uncertain factors and dynamic parameters influence in power system operation,the corresponding integer order mathematical models are established in two cases: external disturbance and self parameters change.When analyzing the influence of parameter changes on the system stability,the voltage instability conditions are analyzed from different load angles,and the bifurcation behavior of the system is judged by searching the voltage balance boundary curve.The bifurcation diagram,time sequence diagram and attractor phase diagram of the system are drawn by MATLAB simulation platform to show the process from stable operation to instability caused by external disturbance or internal parameter changes.Secondly,the voltage stability control algorithm of integer fourth-order power system is studied.Firstly,the classical state feedback controller is designed to show the controllability of the system.Then,in order to improve the response speed and accuracy of the control,the influence of external disturbance and self parameters variation on system stability is considered comprehensively,a nonlinear controller is designed based on the principle of immersion and invariance,combined with the sliding mode adaptive control algorithm.The effectiveness of the controller is verified by experiments,and the expected effect is achieved.Finally,combined with the fractional calculus theory,the mathematical model of fractional order power system is established.Through the dynamic behavior analysis,it is found that the change of fractional order will affect the voltage stability of the system.In order to maintain the stable operation of fractional order power system,fractional sliding mode control algorithm is used to design the controller.Theoretical analysis and simulation results show that the control algorithm can achieve the effect of power system chaos suppression and keep the system in a stable state,which proves the effectiveness of this method.