PHOTOVOLTAIC ENERGY SYSTEM WITH PREEMPTIVE RAMP RATE CONTROL

• US 20170102675A1
• Filed: 08/25/2016
• Published: 04/13/2017
• Est. Priority Date: 10/08/2015
• Status: Active Grant

• Current Assignee: Con Edison Battery Storage, LLC
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Drees, Kirk H.
• Granted Patent: US 10,564,610 B2
• Time in Patent Office: Days
• CPC Class Codes: G05B 13/0205 not using a model or a simulator of the controlled system
• CPC Class Codes: H02J 2203/20 Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02S 40/00 Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
• CPC Class Codes: H02S 40/30 Electrical components
• CPC Class Codes: H02S 50/00 Monitoring or testing of PV systems, e.g. load balancing or fault identification
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

A photovoltaic energy system includes a photovoltaic field configured to convert solar energy into electrical energy, cloud detectors configured to detect a cloud approaching the photovoltaic field, and a controller. The controller uses the cloud detectors to predict a disturbance in the electric power output of the photovoltaic energy system. The controller determines a time at which the disturbance is expected to occur and determines an amount by which the electric power output is expected to decrease. The controller can preemptively adjust the electric power output of the photovoltaic energy system in accordance with a predetermined ramp rate.

Claims

1. A photovoltaic energy system comprising:

a photovoltaic field configured to convert solar energy into electrical energy provided as an electric power output of the photovoltaic energy system;

one or more cloud detectors configured to detect a cloud approaching the photovoltaic field; and

a controller configured to use input from the one or more cloud detectors to predict a disturbance in the electric power output of the photovoltaic energy system, determine a time at which the disturbance is expected to occur, and determine an amount by which the electric power output is expected to decrease as a result of the disturbance;

wherein the controller is configured to preemptively adjust the electric power output of the photovoltaic energy system before the disturbance occurs in accordance with a predetermined ramp rate.

2. The photovoltaic energy system of claim 1, wherein the controller is configured to:

use the input from the one or more cloud detectors to determine a velocity of the cloud approaching the photovoltaic field;

use the velocity of the cloud to determine the time at which the disturbance is expected to occur.

3. The photovoltaic energy system of claim 1, wherein the controller is configured to determine the time at which the disturbance is expected to occur by predicting at least one of a start time, an end time, and a duration of the disturbance.

4. The photovoltaic energy system of claim 1, wherein the controller is configured to:

use the input from the one or more cloud detectors to determine one or more cloud attributes comprising at least one of a size, a position, and a direction of the cloud approaching the photovoltaic field; and

use the one or more cloud attributes to determine the amount by which the electric power output is expected to decrease as a result of the disturbance.

5. The photovoltaic energy system of claim 1, wherein the controller is configured to determine a time at which to begin preemptively adjusting the electric power output by:

determining an amount of time needed to ramp down the electric power output by the amount which the electric power output is expected to decrease as a result of the disturbance without violating the predetermined ramp rate; and

determining a time at which to start ramping down the electric power by subtracting the amount of time needed to ramp down the electric power output from the time at which the disturbance is expected to occur.

6. The photovoltaic energy system of claim 5, wherein the controller is configured to determine the amount of time needed to ramp down the electric power output by dividing the amount by which the electric power output is expected to decrease by the predetermined ramp rate.

7. A photovoltaic energy system comprising:

a photovoltaic field configured to convert solar energy into electrical energy provided as an electric power output of the photovoltaic energy system;

one or more cloud detectors configured to detect a cloud approaching the photovoltaic field; and

a controller configured to use input from the one or more cloud detectors to predict a decrease in the electric power output of the photovoltaic energy system and determine a time at which to begin preemptively ramping down the electric power output of the photovoltaic energy system before the decrease in the electric power output occurs;

wherein the controller is configured to adjust the electric power output of the photovoltaic energy system by beginning to ramp down the electric power output at the determined time.

8. The photovoltaic energy system of claim 7, wherein the controller is configured to use the predicted decrease in the electric power output in combination with a predetermined ramp rate to determine a minimum amount of time required to decrease the electric power output by an amount of the predicted decrease without exceeding the predetermined ramp rate.

9. The photovoltaic energy system of claim 8, wherein the controller is configured to determine the time at which to begin preemptively ramping down the electric power output by subtracting the minimum amount of time required to decrease the electric power output from a time at which the disturbance is expected to occur.

10. The photovoltaic energy system of claim 7, wherein the controller is configured to monitor the electric power output of the photovoltaic energy system and calculate a rate of change of the electric power output, the rate of change defining an actual ramp rate of the photovoltaic energy system.

11. The photovoltaic energy system of claim 10, wherein the controller is configured to compare the actual ramp rate to a predetermined ramp rate and use feedback control to adjust the electric power output of the photovoltaic energy system in response to the actual ramp rate exceeding the predetermined ramp rate.

12. The photovoltaic energy system of claim 11, wherein the controller is configured to adjust the electric power output such that the actual ramp rate does not exceed the predetermined ramp rate.

13. A renewable energy system comprising:

a renewable energy field that converts a renewable energy source into electrical energy;

one or more sensors configured to detect a change in an environmental condition that will affect an electric power output of the renewable energy field; and

a controller configured to use input from the one or more sensors to predict a decrease in the electric power output of the renewable energy system and determine a time at which to begin preemptively ramping down the electric power output of the renewable energy system before the decrease in the electric power output occurs;

wherein the controller is configured to adjust the electric power output of the renewable energy system by beginning to ramp down the electric power output at the determined time.

14. The renewable energy system of claim 13, wherein the renewable energy field comprises at least one of a photovoltaic field, a wind turbine field, a hydroelectric field, a tidal energy field, and a geothermal energy field.

15. The renewable energy system of claim 13, wherein the controller is configured to use the input from the one or more sensors to predict a change in the environmental condition within the renewable energy field before the change in the environmental condition occurs within the renewable energy field.

16. The renewable energy system of claim 13, wherein the controller is configured to use the input from the one or more sensors to determine a time at which an environmental disturbance is expected to occur and an amount by which the electric power output is expected to decrease as a result of the environmental disturbance.

17. The renewable energy system of claim 16, wherein the controller is configured to use the amount by which the electric power output is expected to decrease in combination with a predetermined ramp rate to determine a minimum amount of time required to decrease the electric power output without exceeding the predetermined ramp rate.

18. The renewable energy system of claim 17, wherein the controller determines a time at which to begin ramping down the electric power output by subtracting the minimum amount of time required to decrease the electric power output from the time at which the environmental disturbance is expected to occur.

19. The renewable energy system of claim 13, wherein the controller is configured to monitor the electric power output of the renewable energy system and calculate a rate of change of the electric power output, the rate of change defining an actual ramp rate of the renewable energy system.

20. The renewable energy system of claim 19, wherein the controller is configured to compare the actual ramp rate to a predetermined ramp rate and use feedback control to adjust the electric power output of the renewable energy system in response to the actual ramp rate exceeding the predetermined ramp rate.