Optimization research on load dispatch in gas-steam combined cycle units

Abstract

ABSTRACT Gas-steam combined cycle units, with gas as fuel, are more efficient than the thermal units. The output of the combined system includes gas turbine and steam turbine load. With the load variation during the operation, it is difficult for the main equipment to keep running under the economic load all the time, and the fuel consumption will increase compared with the optimal working conditions. In this paper, special two-one economic consuming models are established as the base of dispatch problems, with the steam extraction flow and low-pressure water extraction flow as the model input, while the heat output as the model output. A hybrid algorithm is proposed in this paper by integrating the SA strategy into the basic BBO algorithm, called SABBO algorithm, to solve optimization problem. In this modified algorithm, a simulated annealing operator is used to randomly perturb the best individual retains after migration and mutation operating in the basic BBO. A benchmark function is then taken to test the proposed method’s optimal capacity. The proposed algorithm is then used in load optimal distribution model for gas-steam combined cycle units (one-one units and one two-one units). The optimal fuel flow calculated with SABBO algorithm by Optimal 2 is 202.17 t/h, lower than 206.63 t/h by Optimal 1 when power and heat demands are 1000 MW and 575 MW, respectively. Moreover, optimization results by BBO and SABBO algorithms under Optimal 2 solution with demands as [1000, 575], [1000, 700], and [800, 575] MW are listed in the paper. This case tells SABBO algorithm under Optimal 2 solution can be used in gas-steam combined cycle units dispatch problems for lower fuel flow consumption as 202.17 t/h, 211.01 t/h, and 171.76 t/h.