Research On Stochastic Stability Analysis Of Time-delay Power System Under Complex Operating Conditions

Wide area feedback controllers bring time-delay into power system.The existence of time-delay will weaken the performance of wide area controller, even appear the negative damping situation.Cascading failure,external random excitation included in power control and the the rapid development of wind power also bring rich random factors into power system.However,it’s unable to analysis time-delay stability of systemusing the traditional differential equations theory.Therefore,it’s urgent to study the stochastic time-delay stability of the power system. The main contents and results of this paper are:1) Time Delay Stability Analysis of Power System Based on the Fault Chains and Markov Process. The Fault Chains and Markov processes are combined to establish a class of Lyapunov-Krasovskii functional considering Markov jump. Then,the LKF is used to judge the time-delay stability of power system. The method,which can analysis time-delay stability of power system under the cascading failure,makes full use of the Markov process transition rate matrix and delay variation information and is less conservative.2) Time Delay Stability Analysis of Stochastic Power System Based on Ito Differential. A criterion for the stochastic stability of power system is provided by Ito differentiation formula. This method greatly reduces the conservative in time-delay stochastic stability criterion and could be applied under the harsh conditions of overload、weak damping and high excitation amplification.3) Stochastic Time Delay Stability Analysis of Wind Power integrated Power Systems. The state equations of interconnected system expressed by stochastic differential equations (SDE) are established. The discrimination method of stochastic stability of interconnected power systems under random excitation is obtained by Ito differentiation formula.In this method,mechanical system modal of double fed induction motor is described by Wiener process. The influence of the randomness of wind speed on the time-delay stability of the power system is comprehensively analyzed. The simulation results verify the correctness, validity and conservativeness of above methods.