Advance Dispatch Procedures for the Centralized Control of Real Power

In a modern control center the availability of the on-line state-estimation and load forecasting can be exploited by the system operators in order to redefine optimal and secure operation strategies a very short period in advance. Therefore in the system control hierarchy an Advance Dispatching (AD) activity is added between the day before scheduling and the on-line Economic Dispatch (ED). AD is a useful tool for improving the system operation before the availability of a closed-loop ED and for supplying security constrained participation factors to the regulating units when ED is operating. To be more precise AD modifies the day before scheduling by supplying the optimal trajectories of the thermal units over very short time periods taking into due account the load predictions (30 minutes ahead) and the actual security constraints which include dynamic limitations upon the rates of change of the thermal generator MW outputs. For the real-time environment, the AD computational procedures have to be quick and reliable in spite of the additional burden of the dynamic constraints. These objectives have been accomplished by introducing appropriate simplifications in the optimal control problem which is a result of the dynamic dispatch formulation. Although accuracy in critical newtork security constraints and in active losses rappresentation is still provided for, the adoption of a parametric linear programming algorithm in the AD procedure provides a very fast and adeguate solution to the problem.