COORDINATED ECONOMIC AND ADVANCE DISPATCH PROCEDURES

The paper deals with the problem of improving co-ordination between th e on-hire economic dispatch (ED) function and the very short term adva nce dispatch (AD). Both procedures are formulated as optimal dispatchi ng problems, but while a static model is used for the ED function, a d ynamic model is employed in AD. The need to account for ramp-rate limi ts of thermal generations even in the ED phase is satisfied by adding suitable penalty terms to the objective function of the classical ED p roblem. These penalties are proportional to the. Lagrange multipliers associated with ramp-rate limits that are active at the AD solution. A n efficient updating procedure is used to correct the penalization by taking the load forecast errors into account. The proposed co-ordinati on procedure can provide the snapshot ED with the long range perspecti ve of AD without resorting to heuristic approaches. The procedure is v alidated by extensive testing carried out both on a small CIGRE test c ase and on a medium-large scale network representative of the Italian EW system. Moreover, test res;lts show that the CPU time requirements of the modified ED procedure are still suited to online applications.