摘要 |
To derive a feasible solution for an operation plan problem for storage tanks for storing liquefied natural gas, which is a complicated mixed-integer non-linear problem, given tank initial state information, reception plan information, and feed plan information, two solving processes are executed alternately two or more times, respectively: a first solving process that replaces a mixed-integer non-linear programming problem with a mixed-integer linear programming problem by linear approximation of a non-linear expression in non-linear constraints containing the non-linear expression, and solves the problem to derive provisional solutions or final solutions for a reception pattern that prescribes a storage tank that is to receive liquefied natural gas, and a discharge pattern that prescribes a storage tank that is to discharge liquefied natural gas, and a second solving process that replaces a mixed-integer non-linear programming problem with a continuous non-linear programming problem by provisionally fixing a discrete variable in discrete form constraints containing the discrete variable, and solves the problem to derive provisional solutions or final solutions for transitions of storage quantity and storage heat quantity of liquefied natural gas in each storage tank. |