This paper proposes the model predictive control approach to dynamic economic dispatch (DED) improving reliability by using closed-loop control scheme. The improving reliability means that this proposed method affects the grid stability related with grid frequency. DED solves the economic based problem but it can weaken the reliability of generation because it does not consider the generator's nonlinear behavior and uncertainty. This makes the unavoidable difference between dispatch level and actual power generation level, and additional control works are needed for grid stability. This eventually increases the operation cost. From this method, generators could be distinguished by reliability by comparing the dispatch error which is the difference between dispatch power reference and actual generator output power. Finally, this method guarantees the more active dispatch by adapting the current generation status at every dispatch time step. Consequently, improving the reliability of generation reduces the total cost.