A method and system for online power management of a turbine engine is provided. The method includes operating an engine control system on a first bandwidth, filtering at least one data input from the engine control system to a second bandwidth, and receiving, by a power management system operating on the second bandwidth, the at least one filtered data input. The method also includes predicting an engine operating condition using the at least one filtered data input using a closed-loop engine model, determining an optimal engine power management based on the prediction, solving a constrained optimization for a desired optimization objective, and outputting the optimal engine power management to the engine control system.