Peak shaving using energy storage

Patent metadata

Field	Value
Publication number	US-10063053-B2
Application number	US-201514802581-A
Country	US
Kind code	B2
Filing date	Jul 17, 2015
Priority date	May 4, 2015
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

Methods for controlling an energy storage device to reduce peak power demand at a site are provided. In one embodiment, load data corresponding to a load in a utility grid-connecting energy generation (EG) system is received. The load data may be sampled at a first predetermined interval, and the EG system may include an energy storage device. A load threshold level is received, and a discharge control signal is generated. The discharge control signal may be generated when the measured load is at or above the load threshold level. The control signal may be applied to the measured load for a second predetermined interval that is longer than the first predetermined interval.

First claim

What is claimed is:

1. A method comprising:
receiving, at a processor, load data corresponding to a load in a utility grid-connected energy generation (EG) system, wherein the load data is sampled at a sampling rate, and wherein the EG system includes an energy storage device;
receiving, at the processor, a load threshold level;
generating, by the processor when the measured load is at or above the load threshold level, a discharge control signal to discharge the energy storage device to reduce the load to the load threshold level, wherein the discharge control signal is applied to the measured load at a forecasting rate having a frequency lower than that of the sampling rate; and
generating, when the measured load is below the load threshold, a charge control signal to charge the energy storage device to increase the load to the load threshold level, wherein the charge control signal is applied to the measured load for a period of time defined by the forecasting rate.

2. The method of claim 1 , wherein the energy storage device is discharged by an amount corresponding to a difference between the load in the utility grid-connected EG system and the load threshold level.

3. The method of claim 2 , wherein the difference is determined by the difference between the current load value and the load threshold level.

4. The method of claim 1 , wherein generating the charge control signal is performed during a time period when energy is generated by the EG system.

5. The method of claim 1 , wherein the discharge control signal discharges the energy storage device according to a forecasted trend.

6. The method of claim 5 , wherein the forecasted trend causes the discharge control signal to maintain the last known value prior to generating another discharge control signal such that the trend of the discharge control signal is constant across an entire period of time defined by the forecasting rate.

7. The method of claim 5 , wherein the forecasted trend is determined by referencing historical records of the load data.

8. The method of claim 7 , wherein the historical records of the load data is a time period immediately prior to the generating the discharge control signal.

9. The method of claim 5 , wherein the forecasted trend is determined by referencing a weather forecast indicating the effect of weather on energy generation and energy consumption.

10. The method of claim 1 , further comprising comparing the load level to a peak threshold amount, wherein the peak threshold amount is a highest-reached load value, and wherein the load threshold level is at a calculated difference below the peak threshold amount.

11. The method of claim 10 , wherein the calculated difference is determined by a capacity of the energy storage device.

12. The method of claim 10 , further comprising increasing the peak threshold level and the load threshold level when the load level is greater than the peak threshold amount.

13. The method of claim 12 , wherein the peak threshold level and the load threshold level is increased by an amount corresponding to the difference between the load threshold level and the peak threshold amount.

14. A system comprising:
a processor configured to:
receive load data corresponding to a load in a utility grid-connected energy generation (EG) system, wherein the load data is sampled at a sampling rate, and wherein the EG system includes an energy storage device;
set a load threshold level;
generate, when the measured load is at or above the load threshold, a discharge control signal to discharge the energy storage device to reduce the load to the load threshold level, wherein the discharge control signal is applied to the measured load at a forecasting rate having a frequency lower than that of the sampling rate; and
generate, when the measured load is below the load threshold, a charge control signal to charge the energy storage device to increase the load to the load threshold level, wherein the charge control signal is applied to the measured load for a period of time defined by the forecasting rate.

15. The system of claim 14 , wherein the energy storage device is discharged by an amount corresponding to a difference between the load in the utility grid-connected EG system and the load threshold level.

16. The system of claim 15 , wherein the difference is determined between the current load value and the load threshold level.

17. The system of claim 14 , wherein the discharge control signal discharges the energy storage device according to a forecasted trend.

18. A non-transitory computer readable medium having stored thereon program code executable by a processor, the program code comprising:
code that receives load data corresponding to a load in a utility grid-connected energy generation (EG) system, wherein the load data is sampled at a sampling rate, and wherein the EG system includes an energy storage device;
code that sets a load threshold level;
code that generates, when the measured load is at or above the load threshold, a discharge control signal to discharge the energy storage device to reduce the load to the load threshold level, wherein the discharge control signal is applied to the measured load at a forecasting rate having a frequency lower than that of the sampling rate; and
code that generates, when the measured load is below the load threshold, a charge control signal to charge the energy storage device to increase the load to the load threshold level, wherein the charge control signal is applied to the measured load for a period of time defined by the forecasting rate.

19. The non-transitory computer readable medium of claim 18 , wherein the energy storage device is discharged by an amount corresponding to a difference between the load in the utility grid-connected EG system and the load threshold level.

20. The non-transitory computer readable medium of claim 19 , wherein the difference is determined by the difference between the current load value and the load threshold level.

Assignees

• Solarcity Corp

Inventors

• Carlson Eric Daniel
• Murthy Nathan

Classifications

• Y04S20/222

  Demand response systems, e.g. load shedding, peak shaving · CPC title

• Y02B70/3225

  Demand response systems, e.g. load shedding, peak shaving · CPC title

• H02J2105/12

  supplying households or buildings · CPC title

• H02J3/14 Primary

  by switching loads on to, or off from, the networks, e.g. progressively balanced loading · CPC title