METHOD OF LOAD SHEDDING TO REDUCE THE TOTAL POWER CONSUMPTION OF A LOAD CONTROL SYSTEM

• US 20100117621A1
• Filed: 01/20/2010
• Published: 05/13/2010
• Est. Priority Date: 10/13/2006
• Status: Abandoned Application

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Cash, Audwin, Veskovic, Dragan, Rigatti, Christopher J.
• Application Number:
  US12/690,637
• Publication Number:
  US 20100117621A1
• Time in Patent Office: Days
• US Class Current: 323/318
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: H05B 41/3921 with possibility of light intensity variations
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/246 the system involving the remote operation of lamps or lighting equipment

Abstract

A method of determining a setpoint of a load control device for controlling the amount of power delivered to an electrical load located in a space, the method comprising the steps of initially setting the value of the setpoint equal to a desired level; limiting the value of the setpoint to an occupied high-end trim if the space is occupied; limiting the value of the setpoint to a daylighting high-end trim determined by a daylighting procedure; and subsequently reducing the value of the setpoint in response to a load shed parameter.

Claims

1. A method of determining a setpoint of a load control device for controlling the amount of power delivered to an electrical load located in a space, the method comprising the steps of:

initially setting the value of the setpoint equal to a desired level;

limiting the value of the setpoint to an occupied high-end trim if the space is occupied;

limiting the value of the setpoint to a daylighting high-end trim determined by a daylighting procedure; and

subsequently reducing the value of the setpoint in response to a load shed parameter.

2. The method of claim 1, wherein, as the value of the load shed parameter increases, the value of the setpoint decreases.

3. The method of claim 2, wherein the step of subsequently reducing the value of the setpoint in response to a load shed parameter comprises calculating the value of the new setpoint as a function of the previous setpoint and the load shed parameter.

4. The method of claim 1, wherein the step of subsequently reducing the value of the setpoint in response to a load shed parameter comprises multiplying the setpoint by a factor that is dependent upon the load shed parameter.

5. The method of claim 4, wherein the step of subsequently reducing the value of the setpoint in response to a load shed parameter comprises calculating the value of the new setpoint from the equation:

New Setpoint=Previous Setpoint·

(100−

Load Shed Parameter)/100.

6. The method of claim 1, further comprising the step of:

controlling the amount of power delivered to the electrical load in response to the setpoint.

7. The method of claim 1, wherein the value of the load shed parameter is determined as part of a load shedding procedure.

8. The method of claim 1, further comprising the step of:

receiving a digital message containing a command to control the amount of power delivered to the electrical load to the desired level.

9. The method of claim 1, further comprising the steps of:

increasing the daylighting high-end trim if the daylighting procedure determines that the amount of daylight in the space has decreased; and

decreasing the daylighting high-end trim if the daylighting procedure determines that the amount of daylight in the space has increased.

10. A method of controlling the amount of power delivered from an AC power source to an electrical load located in a space, the method comprising the steps of:

receiving a digital message containing a command to control the amount of power delivered to the electrical load to a desired level;

detecting if the space is occupied; and

determining a daylighting high-end trim using a daylighting procedure;

wherein the improvement comprises the steps of;

receiving a load shed parameter; and

determining the amount of power to be delivered to the electrical load by limiting the amount of power to be delivered to the electrical load to the minimum of the desired level of the digital message, an occupied high-end trim, and the daylighting high-end trim, and by reducing the amount of power to be delivered to the electrical load in response to the load shed parameter.

11. A load control device for controlling the amount of power delivered from an AC power source to an electrical load located in a space, the load control device comprising:

means for initially setting the value of the setpoint equal to a desired level;

means for limiting the value of the setpoint to an occupied high-end trim if the space is occupied;

means for limiting the value of the setpoint to a daylighting high-end trim determined by a daylighting procedure; and

means for subsequently reducing the value of the setpoint in response to a load shed parameter.

12. A load control device of a load control system for controlling the amount of power delivered from an AC power source to an electrical load located in a space, the load control device comprising:

a load control circuit adapted to be coupled to the AC power source and the electrical load to control the amount of power delivered to the electrical load;

a control circuit coupled to the load control circuit for controlling the amount of power delivered to the electrical load;

a memory coupled to the control circuit and operable to store a load shed parameter;

a communication circuit coupled to the control circuit and operable to receive a digital message representative of a desired amount of power to deliver to the electrical load;

an occupancy sensor input for receiving an occupancy sensor signal representative of whether the space is occupied, the control circuit operable to determine an occupied high-end trim in response to the occupancy sensor signal; and

a daylight sensor input for receiving a daylight sensor signal representative of the total illumination in the space, the control circuit operable to determine a daylighting high-end trim in response to the daylighting sensor signal;

wherein the control circuit is operable to determine the amount of power to be delivered to the electrical load by limiting the amount of power to be delivered to the electrical load to the minimum of the desired level of the digital message, the occupied high-end trim, and the daylighting high-end trim, and by reducing the amount of power to be delivered to the electrical load in response to the load shed parameter.

13. A load control device of claim 12, wherein the control circuit is operable to receive the load shed parameter via the communication circuit, and to store the load shed parameter in the memory.