Power control system with battery power setpoint optimization using one-step-ahead prediction

• US 20170104343A1
• 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: ElBsat, Mohammad N., Wenzel, Michael J., Lenhardt, Brett M.
• Granted Patent: US 10,700,541 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 31/387 Determining ampere-hour charge capacity or SoC
• 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 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02S 50/00 Monitoring or testing of PV systems, e.g. load balancing or fault identification
• CPC Class Codes: Y02B 10/10 Photovoltaic [PV]
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin
• CPC Class Codes: Y04S 10/50 Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

A predictive power control system includes a battery configured to store and discharge electric power, a battery power inverter configured to control an amount of the electric power stored or discharged from the battery, and a controller. The controller is configured to predict a power output of a photovoltaic field and use the predicted power output of the photovoltaic field to determine a setpoint for the battery power inverter.

Claims

1. A predictive power control system comprising:

a battery configured to store and discharge electric power;

a battery power inverter configured to control an amount of the electric power stored or discharged from the battery;

a controller configured to predict a power output of a photovoltaic field and use the predicted power output of the photovoltaic field to determine a setpoint for the battery power inverter.

2. The system of claim 1, wherein the controller is configured to determine the setpoint for the battery power inverter in order to comply with a ramp rate limit.

3. The system of claim 1, wherein the controller is configured to determine a current state-of-charge of the battery and use the current state-of-charge of the battery to determine the setpoint for the battery power inverter.

4. The system of claim 1, wherein the controller is configured to predict the power output of the photovoltaic field by:

generating a state-space model that represents the power output of the photovoltaic field;

identifying parameters of the state-space model using an autoregressive moving average technique based on a history of values of the power output of the photovoltaic field;

using a Kalman filter in combination with the identified state-space model to predict the power output of the photovoltaic field at a next instant in time.

5. The system of claim 1, wherein the controller is configured to:

use the predicted power output of the photovoltaic field to determine that a portion of the power output of the photovoltaic field must be stored or limited in order to comply with a ramp rate limit;

determine whether a current state-of-charge of the battery is above or below a state-of-charge setpoint for the battery; and

generate a ramp rate control power setpoint based on whether the current state-of-charge of the battery is above or below the state-of-charge setpoint, the ramp rate control power setpoint indicating an amount of power to store in the battery in order to comply with the ramp rate limit.

6. The system of claim 5, wherein the controller is configured to:

determine that the current state-of-charge of the battery is below the state-of-charge setpoint; and

generate the ramp rate control power setpoint based on an amount by which the state-of-charge setpoint exceeds the current state-of-charge of the battery.

7. The system of claim 5, wherein the controller is configured to:

determine that the current state-of-charge of the battery is above the state-of-charge setpoint or within a range of values defined by an upper setpoint limit and a lower setpoint limit;

determine a minimum amount of power required to be stored in the battery in order to comply with the ramp rate limit; and

generate the ramp rate control power setpoint by setting the ramp rate control power setpoint to the determined minimum amount of power to be stored in the battery in order to comply with the ramp rate limit.

8. A power control system comprising:

a battery configured to store and discharge electric power;

a battery power inverter configured to control an amount of the electric power stored or discharged from the battery;

a photovoltaic power inverter configured to control an electric power output of a photovoltaic field;

a controller configured to determine a state-of-charge of the battery, determine a ramp state of the electric power output of the photovoltaic field, and generate a setpoint for the battery power inverter and a setpoint for the photovoltaic power inverter based on the determined state-of-charge and the determined ramp state.

9. The system of claim 8, wherein the controller is configured to determine the ramp state by determining whether the power output of the photovoltaic field is ramping-up at a rate that exceeds a ramp rate limit, ramping-down at a rate that exceeds the ramp rate limit, or ramping at a rate that does not exceed the ramp rate limit.

10. The system of claim 9, wherein in response to a determination that the electric power output is ramping-up at a rate that exceeds the ramp rate limit, the controller is configured to set the setpoint for the battery power inverter to zero and control a ramp rate of the power control system by adjusting the setpoint for the photovoltaic power inverter.

11. The system of claim 8, wherein in response to a determination that the state-of-charge of the battery is a charged state, the controller is configured to set the setpoint for the battery power inverter to zero and control a ramp rate of the power control system by adjusting the setpoint for the photovoltaic power inverter.

12. The system of claim 8, wherein the controller is configured to:

cause the battery power inverter to charge the battery in response to a determination that the state-of-charge of the battery is below a state-of-charge setpoint; and

cause the battery power inverter to discharge the battery in response to a determination that the state-of-charge of the battery is above the state-of-charge setpoint.

13. The system of claim 8, wherein the controller is configured to:

determine that the current state-of-charge of the battery is below a state-of-charge setpoint or within a range of values defined by an upper setpoint limit and a lower setpoint limit;

determine a minimum amount of power required to be discharged from the battery in order to comply with a ramp rate limit; and

generate the setpoint for the battery power inverter by setting the setpoint for the battery power inverter to the determined minimum amount of power to be discharged from the battery in order to comply with the ramp rate limit.

14. A method for operating a battery power inverter, the method comprising:

predicting a power output of a photovoltaic field;

determining a setpoint for the battery power inverter using the predicted power output of the photovoltaic field; and

using the determined setpoint for the battery power inverter to control an amount of electric power stored or discharged from the battery by the battery power inverter.

15. The method of claim 14, wherein determining the setpoint for the battery power inverter comprises generating the setpoint to ensure compliance with a ramp rate limit.

16. The method of claim 14, further comprising determining a current state-of-charge of the battery and using the current state-of-charge of the battery to determine the setpoint for the battery power inverter.

17. The method of claim 14, wherein predicting the power output of the photovoltaic field comprises:

generating a state-space model that represents the power output of the photovoltaic field;

identifying parameters of the state-space model using an autoregressive moving average technique based on a history of values of the power output of the photovoltaic field;

using a Kalman filter in combination with the identified state-space model to predict the power output of the photovoltaic field at a next instant in time.

18. The method of claim 14, further comprising:

using the predicted power output of the photovoltaic field to determine that a portion of the power output of the photovoltaic field must be stored or limited in order to comply with a ramp rate limit;

determining whether a current state-of-charge of the battery is above or below a state-of-charge setpoint for the battery; and

generating a ramp rate control power setpoint based on whether the current state-of-charge of the battery is above or below the state-of-charge setpoint, the ramp rate control power setpoint indicating an amount of power to store in the battery in order to comply with the ramp rate limit.

19. The method of claim 18, wherein:

determining whether a current state-of-charge of the battery is above or below a state-of-charge setpoint for the battery comprises determining that the current state-of-charge of the battery is below the state-of-charge setpoint; and

generating the ramp rate control power setpoint comprises generating the ramp rate control power setpoint based on an amount by which the state-of-charge setpoint exceeds the current state-of-charge of the battery.

20. The method of claim 18, wherein:

determining whether a current state-of-charge of the battery is above or below a state-of-charge setpoint for the battery comprises determining that the current state-of-charge of the battery is above the state-of-charge setpoint or within a range of values defined by an upper setpoint limit and a lower setpoint limit; and

generating the ramp rate control power setpoint comprises;

determining a minimum amount of power required to be stored in the battery in order to comply with the ramp rate limit; and

setting the ramp rate control power setpoint to the determined minimum amount of power to be stored in the battery in order to comply with the ramp rate limit.