To solve various security economic dispatch problems， such as generator ramp rate limits， a master-slave optimization model and iterative solving mechanism based on Dantzig-Wolfe decomposition are proposed. In the master problem， only time correlation constraints are considered with the solution areas determined by slave problems. Depending on the study periods， the slave problems are made up of some static optimization sub-problems. In order to decouple the time correlation constraints indirectly， the slave problems objective functions are modified with the Lagrangian multipliers corresponding to the optimal solution of the master problem. Based on the convergence conditions and examples of the iterative solutions， the detailed algorithm and special problem solutions are proposed. Simulation results on the 5-generator system， the IEEE 24-node system and the IEEE 118-node system indicate the effectiveness of the proposed method and its prospect of large scale application in practice.