Increasing the demand reduction effectiveness of an energy storage system
In various embodiments, a hedge mode plugin increases the ability of an energy storage system to reduce the demand charges associated with purchasing electricity from a utility. A utility measurement interval (UMI) is divided into a pre-discharge phase and a subsequent compensatory charge phase. During the pre-discharge phase, the hedge mode plugin causes an energy storage device to discharge. At the beginning of the compensatory charge phase, the hedge mode plugin computes time-indexed charge values based on the total amount of energy that the energy storage device discharged during the pre-discharge phase. The hedge mode plugin then causes the energy storage device to charge based on at least one of the charge values. By systematically pre-discharging and re-charging the energy device, the hedge mode plugin optimizes the demand reduction effectiveness of the energy storage system during each UMI while stabilizing the state-of-charge of the energy storage device across multiple UMIs.
1. A computer-implemented method for controlling an energy storage device to manage power-limited events, the method comprising:
computing a plurality of discharge values, wherein each discharge value included in the plurality of discharge values corresponds to a distinct time that lies within a pre-discharge phase of a utility measurement interval and is based on the distinct time and a pre-defined discharge curve that comprises one of a linear function or a Bezier function;
during the pre-discharge phase, causing the energy storage device to discharge electrical energy based on at least one discharge value included in the plurality of discharge values;
at a predetermined time that separates the pre-discharge phase from a compensatory charge phase of the utility measurement interval, computing a plurality of charge values based on a total amount of electrical energy that is discharged from the energy storage device during the pre-discharge phase; and
during the compensatory charge phase, causing the energy storage device to perform a charging operation based on at least one charge value included in the plurality of charge values.
2. The method of claim 1 , wherein computing the plurality of charge values comprises:
computing a target amount of compensation energy based on the total amount of electrical energy that is discharged from the energy storage device during the pre-discharge phase and an efficiency loss that is associated with the energy storage device;
parameterizing, based on the target amount of compensation energy, a pre-defined charge curve to generate a parameterized charge curve; and
for each of a plurality of times that lie within the compensatory charge phase, computing a charge value that is included in the plurality of charge values and is based on the parameterized charge curve and the time.
3. The method of claim 2 , wherein the pre-defined charge curve comprises a linear function or a Bezier function.
4. The method of claim 2 , wherein parameterizing the pre-defined charge curve comprises:
selecting a first set of values for parameters associated with the pre-defined charge curve to generate a first potential charge curve;
integrating the first potential charge curve over a time duration of the compensatory charge phase to produce a first total charge energy; and
determining that the first total charge energy is greater than or equal to the target amount of compensation energy.
5. The method of claim 2 , wherein parameterizing the pre-defined charge curve comprises:
determining that a first total charge energy associated with a first set of values for parameters associated with the pre-defined charge curve is less than the target amount of compensation energy;
modifying at least one value included in the first set of values to generate a second set of values for the parameters; and
determining that a second total charge associated with the second set of values for the parameters is greater than or equal to the target amount of compensation energy.
6. The method of claim 5 , wherein the parameters comprise curvature vector parameters.
7. The method of claim 1 , wherein causing the energy storage device to discharge comprises transmitting a discharge command that specifies the at least one of the discharge values included in the plurality of discharge values to a system controller that controls the energy storage device.
8. One or more non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause the one or more processors to control an energy storage device to manage power-limited events by performing the steps of:
computing a plurality of discharge values, wherein each discharge value included in the plurality of discharge values corresponds to a distinct time that lies within a pre-discharge phase of a utility measurement interval and is based on the distinct time and a pre-defined discharge curve that comprises one of a linear function or a Bezier function;
during the pre-discharge phase, causing the energy storage device to discharge electrical energy based on at least one discharge value included in the plurality of discharge values;
at a predetermined time that separates the pre-discharge phase from a compensatory charge phase of the utility measurement interval, computing a plurality of charge values based on a total amount of electrical energy that is discharged from the energy storage device during the pre-discharge phase; and
during the compensatory charge phase, causing the energy storage device to perform a charging operation based on at least one charge value included in the plurality of charge values.
9. The one or more non-transitory computer-readable media of claim 8 , wherein computing the plurality of charge values comprises:
computing a target amount of compensation energy based on the total amount of electrical energy that is discharged from the energy storage device during the pre-discharge phase and an efficiency loss that is associated with the energy storage device;
parameterizing, based on the target amount of compensation energy, a pre-defined charge curve to generate a parameterized charge curve; and
for each of a plurality of times that lie within the compensatory charge phase, computing a charge value that is included in the plurality of charge values and is based on the parameterized charge curve and the time.
10. The one or more non-transitory computer-readable media of claim 9 , wherein parameterizing the pre-defined charge curve comprises:
determining that a first total charge energy associated with a first set of values for parameters associated with the pre-defined charge curve is less than the target amount of compensation energy;
modifying at least one value included in the first set of values to generate a second set of values for the parameters; and
determining that a second total charge associated with the second set of values for the parameters is greater than or equal to the target amount of compensation energy.
11. The one or more non-transitory computer-readable media of claim 10 , wherein the parameters comprise curvature vector parameters.
12. The one or more non-transitory computer-readable media of claim 8 , wherein causing the energy storage device to perform a charging operation comprises transmitting a charge command that specifies the at least one of the charge values included in the plurality of charge values to a system controller that controls the energy storage device.
13. A system configured to control an energy storage device to manage power-limited events, the system comprising:
a memory storing a hedge mode application; and
a processor that is coupled to the memory and, when executing the hedge mode application, is configured to:
compute a plurality of discharge values, wherein each discharge value included in the plurality of discharge values corresponds to a distinct time that lies within a pre-discharge phase of a utility measurement interval and is based on the distinct time and a pre-defined discharge curve that comprises one of a linear function or a Bezier function,
during the pre-discharge phase, cause the energy storage device to discharge electrical energy based on at least one discharge value included in the plurality of discharge values,
at a predetermined time that separates the pre-discharge phase from a compensatory charge phase of the utility measurement interval, compute a plurality of charge values based on a total amount of electrical energy that is discharged from the energy storage device during the pre-discharge phase, and
during the compensatory charge phase, cause the energy storage device to perform a charging operation based on at least one charge value included in the plurality of charge values.
14. The system of claim 13 , wherein the hedge mode application configures the processor to compute the plurality of charge values by:
computing a target amount of compensation energy based on the total amount of electrical energy that is discharged from the energy storage device during the pre-discharge phase and an efficiency loss that is associated with the energy storage device;
parameterizing, based on the target amount of compensation energy, a pre-defined charge curve to generate a parameterized charge curve; and
for each of a plurality of times that lie within the compensatory charge phase, computing a charge value that is included in the plurality of charge values and is based on the parameterized charge curve and the time.
15. The system of claim 13 , wherein the predetermined time comprises a time that bisects the utility measurement interval with respect to time.
16. The system of claim 13 , wherein the energy storage device comprises one or more battery appliances.