Research On Stability Analysis And Control Strategy Of Power System Considering Control Signal Delay

With the implementation of Project "Delivering Electricity from the West to the East, exchanging power between South and North, Interconnecting the whole country", a large-scale interconnected power grid is forming in our country. At the same time, the problem of low frequency oscillation is more and more severe. Based on the wide area measurement system, wide area optimized unified and coordinated control strategy has become one possible method to protect the security and stability of the interconnected power grid. Meanwhile, the distinguishing disadvantage of wide area measurement system is the presence of significant data delays. This paper considers the situation of operating condition constant and operating condition hopping of power system. Using the time-domain method, the stability analisys and control strategy of control signal delay power system is analyzed in this paper. The main contents and results of this paper are:The method to determine the non-jump time-delay upper-bound of the existing wide-area controller of low frequency oscillation, when power system operating condition is constat, based on improved free-weighting matrix and generalized eigenvalue problem (gevp) is proposed in this paper. Firstly, a new class of Lyapunov-Krasovskii functional is constructed. Second, the derivation function along the system is solved. On this basis, necessary loose items are added to the derivation function in order to reduce the conservative, and a set of matrix linear inequalities is formed. Then the upper-bound of delay stability of non-jump controller is solved by means of gevp.The method, based on discrete Markov theory, to analyse the jump time-delay stability of power system is proposed in this paper. Firstly, a new class of Lyapunov-Krasovskii functional is constructed, which Markov jump probability density matrix is added to. Second, the derivation function along the system is solved. Loose items constructed by the Newton-Leibniz formula are added to the derivation function in order to reduce the conservative. On this basis, a set of matrix linear inequalities is formed. Then the maximum time-delay that system can stand, when operation mode adjusting, operation parameter changing and load flow fluctuating, is solved by means of gevp. Finally, the simulation results of the IEEE4-machine11-bus system and IEEE16-machine68-bus test system demonstrate that the correctness and effectiveness of the method in solving time-delay stability upper-bound considering the jump characteristics of power system.The nonlinearity decoupled non-jump and jump time-delay control strategy of power system is proposed in this paper. With the Newton-Leibniz formula indicated by free weighting matrix and time-delay differential equation brought into Lyapuno-Krasovskii functional, the low conservative time-delay stability criterion and nonlinearity minimization control algorithm are formed. With the nonlinearity of the algorithm decoupled by Schur complement, the matrix inequality with nonlinearity is transformed to standard linear matrix inequality, and the non-jump time delay control algorithm is formed. The jump time-delay control algorithm is derivated by Markov transition probability density matrix introduced to non-jump time delay control algorithm. The efficiency problem of iterative is avoided. The time-domain simulation results of IEEE4-generators and11-buses power system and16-generators and68-nodes power system verify the effective control to power system oscillations.