Power System Stability Analysis Based On Stochastic Energy Function

The continuous increase of interconnection scale makes random disturbances more and more common,which are mostly caused by faults and loads.For example,the random fluctuation of load,the uncertainty of wind speed in wind power generation and so on.All of these random disturbances can have a light or heavy impact on the stability of power system.Power system has high dimensionality and strong nonlinearity,and it also has random phenomena in varying degrees.In addition,the construction of smart grid and the wide access of new energy power also bring various random factors,so it is imperative to study the stochastic stability of power system.This paper expounds the basic problems of power system stability and its stochastic stability,and analyses the existing definitions,classifications,research methods and shortcomings of power system stability from two aspects of deterministic analysis method and stochastic stability method.Then the stochastic stability of power system is analyzed by constructing a new Lyapunov function,and its stochastic stability is verified by means of Lyapunov exponent.The research work in this paper includes the following aspects:1.Considering the concepts and classifications of stability and stochastic stability of new energy power systems,based on the analysis of current research situation at home and abroad,the construction and methods of stochastic stability analysis model of new energy power systems are summarized,and potential scientific problems and research methods are put forward.2.For a single machine infinite bus system with Gaussian random excitation,the Lyapunov function of the system is constructed by combining the energy function method,the variable separation method and the variable gradient method,and the weak random asymptotic stability of the system is proved.Then,the simulation calculation is carried out to verify the weak random asymptotic stability of the system.3.Based on EEAC theory,the two-machine system is transformed into a single machine infinite bus system.The Lyapunov function of the two-machine system is constructed by the method of separating variables,and the stochastic stability of the two-machine system is discussed.4.Taking the stochastic single machine infinite bus system as the research model,the approximate steady-state probability density function of the system is calculated,and then the maximum Lyapunov exponent of the stochastic system is obtained.The results show that the maximum Lyapunov exponent is negative and the system is asymptotically stable.