Probabilistic Operation of Electric Power Systems Considering Environmental Constraint (Part l)* -Fundamental Consideration for Instantaneous Operation-

We report an optimum method in which we regard the system load as probabilistic variable and consider both constraints of emission and probabilistic value which exceed the emission constraint. We show that when the outputs of thermal units are constrained to upper and lower limits, even if the system load is represented by the normal distribution, the stochastic character of the total thermal output differs from it and total thermal cost and emission do not become simple curves. The amount of the calculation of fault state is reduced by simplification in our method. We apply our method to a model power system and the results are concluded as follows. Depending on whether we estimate probabilistically or determinately, different optimum groups of thermal units are obtained and the amount of emission from these groups also differ to some extent. For thermal unit’ faults, our practical method can estimate appropriately the optimum operation for almost all values of emission constraints