Method and apparatus for dynamic selection of electric arc-furnace control set-points
An electric arc furnace (EAF) including a set of mast hydraulics, a current transformer, a voltage transformer, a legacy control system and a set-point modifier. The legacy control system is in control of the set of mast hydraulics of the EAF, and receives information from the current transformer relative to current being supplied to the EAF and from the voltage transformer relative to voltage being applied to the EAF. The legacy control system using a set of set-points for the control of the set of mast hydraulics, the voltage and the current of the EAF. The set-point modifier communicates with the legacy control system, and executes the steps of: evaluating a cost function of key performance indicators of a previous heat of the EAF, the key performance indicators including electrical energy use and/or electrode consumption; and altering the set of set-points dependent upon the cost function.
1. An electric arc furnace, comprising:
a set of mast hydraulics;
a current transformer;
a voltage transformer;
a legacy control system in control of the set of mast hydraulics of the electric arc furnace, said legacy control system receiving information from said current transformer relative to current being supplied to the electric arc furnace and from said voltage transformer relative to voltage being applied to the electric arc furnace, said legacy control system having a memory containing a set of set-points for the control of the set of mast hydraulics, the voltage and the current of the electric arc furnace; and
a set-point modifier in communicative connection with said legacy control system, said set-point modifier being configured to
evaluate performance indicators of at least one previous heat of the electric arc furnace, the performance indicators including electrode consumption,
said set of set-points being altered dependent upon said performance indicators by the set point modifier.
2. The electric arc furnace according to claim 1 , wherein said set-point modifier applies coefficients to each of the performance indicators.
3. The electric arc furnace according to claim 2 , wherein said set-point modifier augments at least some of the performance indicators with scaling parameters to arrive at new set point values.
4. The electric arc furnace according to claim 2 , wherein said set-point modifier forms an estimate of a gradient of said performance indicators.
5. The electric arc furnace according to claim 4 , wherein said set-point modifier uses said gradient of said performance indicators to develop a perturbation value for each element of said set of set-points.
6. The electric arc furnace according to claim 5 , wherein said set-point modifier calculates a step length to be used to scale said gradient of said performance indicators.
7. The electric arc furnace according to claim 6 , wherein said set-point modifier sets each set-point value in said set of set points to equal a previous set-point value minus a quantity of said step length times said perturbation value for each set-point value.
8. A device for controlling an electric arc furnace, the device comprising:
a legacy control system in control of the electric arc furnace, said legacy control system having a memory containing a set of set-points for the control of the electric arc furnace; and
a set-point modifier in communicative connection with said legacy control system, said set-point modifier being configured to
evaluate performance indicators of at least one previous heat of the electric arc furnace, the performance indicators including electrode consumption,
said set of set-points being altered dependent upon said performance indicators by the set point modifier.
9. The device according to claim 8 , wherein said set-point modifier applies coefficients to each of the performance indicators.
10. The device according to claim 9 , wherein said set-point modifier augments at least some of the performance indicators with scaling parameters to arrive at new set point values.
11. The device according to claim 9 , wherein said set-point modifier forms an estimate of a gradient of said performance indicators.
12. The device according to claim 11 , wherein said set-point modifier uses said gradient of said performance indicators to develop a perturbation value for each element of said set of set-points.
13. The device according to claim 12 , wherein said set-point modifier calculates a step length to be used to scale said gradient of said performance indicators.
14. The device according to claim 13 , wherein said set-point modifier sets each set-point value in said set of set points to equal a previous set-point value minus a quantity of said step length times said perturbation value for each set-point value.
15. A method for altering set-points of a legacy control system that is in control of an electric arc furnace, the method comprising the steps of:
evaluating performance indicators of at least one previous heat of the electric arc furnace, the key performance indicators including electrode consumption; and
altering said set of set-points dependent upon said performance indicators.
16. The method according to claim 15 , wherein said evaluating step includes the step of applying weighting coefficients to each of the performance indicators.
17. The method according to claim 16 , wherein said evaluating step further includes the step of augmenting at least some of the performance indicators with quadratic penalty terms.
18. The method according to claim 16 , wherein said evaluating step further includes the step of forming an estimate of a gradient of said performance indicators.
19. The method according to claim 18 , wherein said evaluating step further includes the step of using said gradient of said performance indicators to develop a perturbation value for each element of said set of set-points.
20. The method according to claim 19 , wherein said evaluating step further includes the step of calculating a step length to be used to scale said gradient of said performance indicators.