| The economic dispatch problem is one of the basic energy management problems in the power system.It is essentially an optimization problem that aims at minimizing the total generation cost while satisfying the balance between supply and demand and output constraints of each generator.With the expansion of power grid,the traditional centralized dispatching mode can no longer meet the requirements of safe,stable and efficient operation of power grid,while the distributed dispatching mode has better robustness and stability.In the economic dispatch system,communication delays and the change of communication topology are inevitable,and the existence of these factors will affect the system dynamics.Therefore,aiming at the above problems,this thesis designs two distributed economic dispatch algorithms under two kinds of economic dispatch models.The main research contents and achievements are as follows:Aiming at the problem of distributed economic dispatch,a distributed economic dispatch algorithm is proposed under the mathematical model with the cost function considering coal consumption as the main factor and generator power constraint.In this thesis,the time-varying communication delays are considered in the algorithm,and the upper bound of the communication delay allowed by the system is obtained by using the method of time delay division.The communication topology is extended from the connected graph to the case of jointly connected topology.Then,the convergence of the algorithm is analyzed by using Lyapunov stability theory and Cauchy convergence criterion,and the conclusion that the system can converge in finite time under the jointly connected topology is obtained.And a processing mechanism of generator power limitation is designed.Finally,the simulation experiment of five-machine power system verifies the effectiveness of the proposed algorithm under switching topologies and communication delays.Aiming at the economic dispatch problem of wind power units consider in the cost function,a distributed economic dispatch algorithm based on projection dynamics is designed.The differential projection operation and differential inclusion method are used to design the algorithm,and the communication delays and switching topologies are considered in the algorithm.The algorithm is suitable for all power economic dispatch problems with strongly convex cost function,and the algorithm ensures that the output power of each generator is always kept within its output limit.In addition,the upper bound of communication delay allowed by the system is obtained by using the method of time delay division.After that,the convergence of the algorithm is analyzed by using Lyapunov stability theory and Cauchy convergence criterion,and according to La Salle’s invariance principle,the conclusion that the invariant set element that the system finally converges to is unique and the optimal solution of the economic dispatch problem is obtained.Finally,the effectiveness of the algorithm is verified by the simulation experiment,and the comparison experiment illustrate that the proposed algorithm can effectively restrain the influence of communication delays on the convergence of the system. |
