Heat Dispatch Research Articles

Optimal Dispatch in Cogeneration Systems

Abstract This paper presents the principles ot optimal dispatch of heat and electrical power, when the heat and power systems are connected by the cogeneration power plants. The cogeneration system with P units (condensing plants), Q units (boiler plants) and PQ units (cogeneration plants with extraction and back-pressure turbines) are considered. The conditions of optimality using Lagrangian function are presented. In addition to the combined optimization of heat and power the three subproblems are tackled. These subproblems consider the optimal dispatch in different market conditions. A computer program is developed and some practical results are presented.

Stochastic multiobjective generation dispatch of combined heat and power systems

A new stochastic formulation of multiobjective optimisation for combined heat and power system dispatch is presented. Both the power and heat demands are treated as random variables. The three objective functions to be minimised are: the total generation cost, the expected power generation deviation and the expected heat generation deviation. As these objectives are in conflict with each other, only a non-inferior solution can be reached. The goal attainment method is used to solve this multiobjective optimisation problem by assuming that the decision-maker (DM) has desired a certain goal for each of these objectives. Very often, the DM finds it difficult to define the relative importance or a merit function among improving individual objectives and reducing constraint violations. A fuzzy decision index is proposed here to provide the best-compromise solution among all objectives and constraints, and a means of maximising the most underachieved objective. A genetic algorithm approach is also proposed to help the DM to search for such a solution mathematically. Application results of the method to a seven-generator sample system are presented.

An algorithm for combined heat and power economic dispatch

This paper presents a new algorithm for combined heat and power (CHP) economic dispatch. The CHP economic dispatch problem is decomposed into two sub-problems: the heat dispatch; and the power dispatch. The sub-problems are connected through the heat-power feasible region constraints of cogeneration units. The connection can be interpreted by the unit heat-power feasible region constraint multipliers in the Lagrangian function, and the interpretation naturally leads to the development of a two-layer algorithm. The outer layer uses the Lagrangian relaxation technique to solve the power dispatch iteratively. In each iteration, the inner layer solves the heat dispatch with the unit heat capacities passed by the outer layer. The binding constraints of the heat dispatch are fed back to the outer layer to move the CHP economic dispatch towards a global optimal solution.