Probabilistic Operation of Electric Power Systems Considering Environmental Constraint (Part 7)* -A Consideratioin for Line Security-

A scheduling method is reported to satisfy the reliability limit and the environmental constraint when a line fault is regarded as probabilistic. The reliability limit is satisfied by changing the thermal output power to probabilistically achieve every line’s capacity. NO_x emission from thermal stations is limited as a typical environmental constraint. These constraints are economically achieved. The LaGrange’s method and the Kuhn-Tucker conditions are used to satisfy both the line capacity and the emission constraint. The LaGrange’s multipliers are decided by solving the simultaneous equations. An economical method of achieving the reliability limit is described using the probability of the line fault and the increase of the operating cost. Simulating the proposed method by a model system, the results are variously investigated. The proposed method is concretely confirmed to estimate the optimum operation which can economically satisfy the reliability limits and the emission constraints at various values. It is also shown that the proposed method can improve reliability by more than 16％.