Computerized energy management system

• US 4,370,723 A
• Filed: 01/31/1980
• Issued: 01/25/1983
• Est. Priority Date: 01/31/1980
• Status: Expired due to Term

• Current Assignee: Peak Demand Limiters Incorporated
• Original Assignee: Peak Demand Limiters Incorporated
• Inventors: Huffman, Stanley S., Dvorak, Neil E., Swartout, Christopher A., Neel, Alan F.
• Primary Examiner(s): Wise, Edward J.
• Application Number:
  US06/117,381
• Time in Patent Office: 1,090 Days
• Field of Search: 364/493, 364/483, 364/492, 364/418, 307/35, 307/39, 307/41, 307/52, 307/62, 324/103, 236/1 B
• US Class Current: 700/295
• 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 2310/62 The condition being non-electrical, e.g. temperature
• CPC Class Codes: H02J 3/144 Demand-response operation of the power transmission or distribution network
• 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

Abstract

A system for controlling electrical energy consumption according to a user-set kilowatt limit and an automatic kilowatt limit calculated in a microprocessor. Power is limited by regulating an electric hot water heater according to a preset program and, if necessary, by lowering room temperatures due to electric heater cut back. The device features a computer-controlled display and simplified keyboard which permits the user to enter only valid data. The device also features program fail, power fail, and static detect circuitry to prevent computer error.

Claims

1. Power consumption controlling apparatus for use in a facility having a plurality of power consuming loads in various zones, including thermostatically controlled electrically operated space heating devices in some of the zones and electrically operated appliance devices in other of said zones, and comprising:

a power sensing circuit means associated with the main power line to the facility for continuously generating signals representative of total electrical power consumption by electrically operated devices in the facility;

a computer means connected to said power sensing circuit means for receiving said signals and comparing said signals with a predetermined maximum power demand limit set in said computer means;

keyboard means for entering data into the computer, said data including said predetermined maximum power demand limit and an initially selected maximum temperature level for each of a plurality of said electrically operated space heating devices;

an on-off heater control relay means connected to each of the electrically operated space heating devices for controlling the on-off state thereof;

temperature sensors, connected to the computer, for sensing temperature levels in each of the various zones so that said computer may compare each temperature level with a corresponding one of said initial selected maximum temperature levels to actuate said on-off heater control relay means when temperature levels are below said maximum temperature levels except when power consumption exceeds said power demand limit;

an on-off relay means connected to each of the plurality of the electrically operated appliance devices and turned on, to deliver power thereto or turned off by said computer;

a temperature level setting control means in the computer operably associated with each of the on-off heater control relays means for automatically incrementally increasing and decreasing the temperature level setting therefor;

said computer controlling said temperature control means to maintain said initial selected maximum temperature levels except when power consumption exceeds said power demand limit; and

said computer incrementally reducing said initial maximum temperature levels to a plurality of reduced temperature levels a preselected amount below said initial maximum temperature levels while power consumption exceeds said power demand limit.

2. The apparatus of claim 1 wherein said computer selecting one of said plurality of reduced temperature levels on the basis of time over said power demand limit.

3. The apparatus of claim 2 wherein said computer calculates an automatic power demand limit and maintains said preselected reduced temperature levels according to said automatic power demand limit.

4. The apparatus of claim 1 wherein said computer controls said keyboard means to provide a menu of data from which a user selects data to be entered and further comprising:

a display for displaying said menu and for displaying user selected data.

5. The apparatus of claim 1 wherein one of the electrically operated devices comprise:

a hot water heater which is maintained at a preselected level below its external power setting through computer control of one of said relays prior to said reducing of other output levels.

6. Power consumption controlling apparatus for use in a system including a plurality of electrically operable load devices and utilizing a power sensing circuit for continuously measuring total power consumption and a plurality of relays for controlling the amount of power individually consumed by the plurality of load devices, comprising:

a computer for continuously receiving data input from said power sensing circuit representative of total power consumption and for outputting signals to control said relays and reduce total power consumption whenever total power consumption exceeds a predetermined maximum value by selectively reducing power being consumed by the load devices, said signals being dependent on variables including at least one user selected value and including data input from said power sensing circuit and data input relating to the output levels of the load devices;

keyboard means, connected to said computer, for inputting said user selected value to said computer;

display means for displaying said user selected value and data input from said power sensing circuit and data input relating to the output levels of the load devices; and

said computer monitoring the input data from said keyboard means and controlling said display means according to a plurality of preselected values which are sequentially displayed on said display means, so that said keyboard means permits said user selected value to be one of the plurality of preselected values which are sequentially displayed on said display means.

7. The apparatus of claim 6 wherein said computer further comprises:

memory means for storing said data input from said power sensing circuit;

means for automatically calculating said predetermined maximum power consumption value from stored data input; and

said predetermined maximum power consumption value being dependent on said variables.

8. The apparatus of claim 6 or 7 further comprising:

inputs to said computer for sensing temperatures in a number of heating zones which are heated by load devices individually controlled by an equal number of relays.

9. The apparatus of claim 8 wherein said variables include a user selected value representative of a temperature setting for each of said heating zones.

10. The apparatus of claim 6 further comprising:

a real time clock, said real time clock controlling at least one of the load devices

11. The apparatus of claim 6 wherein said keyboard means comprises:

mode keys for selecting one of a plurality of preselected modes, including a mode for selecting said user selected value; and

cycling keys for cycling through said preselected values for a mode selected by the mode keys.

12. A method of controlling power consumption in a facility having a plurality of power consuming loads in various zones, comprising the steps of:

(a) setting a predetermined initial maximum output level and a plurality of more limited lower maximum output levels for a plurality of the power consuming loads;

(b) continuously measuring total power consumption by all power consuming loads in the facility to obtain a total power consumption value;

(c) comparing said power consumption value with a power demand limit value to determine if power consumption is above the power demand limit value;

(d) if so, limiting power to one of said loads and recomparing the total power consumption value with the power demand limit value;

(e) if the power consumption value exceeds the power demand limit value after step (d) is carried out, sequentially lowering the initial maximum output level of other ones of said loads to the limited lower maximum output levels; and

(f) continuing to sequentially lower the output level of the other ones of said loads to the limited lower maximum output levels until total power consumption is less than the power demand limit value.

13. The method of claim 12 further comprising the steps of:

sensing the output level of the loads of paragraphs (e) and (f) of claim 12; and

maintaining said output level at said initial maximum output level when the total power consumption value is below the power demand limit value.

14. The method of claim 13 further comprising the step of:

sounding an alarm if the output level of any load is above said initial maximum output level.

15. The method of claim 12 further comprising the step of:

averaging the total power consumption value over a predetermined time period to obtain an average power consumption value; and

comparing said average power consumption value with said power demand limit value to establish a new power demand limit value.

16. The method of claim 15 further comprising the steps of:

saving said average power consumption value;

calculating an automatic power demand limit value based on said average power consumption value; and

utilizing said automatic power demand limit value as said power demand limit value in steps (b)-(f).

17. The method of claim 15 further comprising the steps of:

setting said limited maximum output level at a first limited maximum output level below said initial maximum output level in steps (e) and (f);

repeating steps (b)-(d);

then if power consumption exceeds the power demand limit value after step (c) is repeated, lowering said first maximum output level to a second maximum output level; and

stopping power consumption of loads having output levels above said second limited maximum output level.

18. An electrical power control system for automatically reducing the total electrical power used in a facility by a plurality of electric operated devices whenever total electrical power usage by the devices exceeds a predetermined maximum power usage level and for thereafter automatically monitoring the amount of reduced available power used and for controlling the amount of reduced available power used by each device in accordance with a preselected priority schedule of usage of reduced available power, the control system being adapted to be associated with a conventional electrical power supply system including:

a main source of power for operating all such devices;

a meter means for measuring the total amount of power being used by all such devices;

a plurality of power transmission circuit means connected to such devices for transmitting power thereto;

circuit breaker means operatively associated with said circuit means for preventing transmission of current to such devices whenever the current level to any one such device exceeds a predetermined maximum current level; and

the control system comprising;

current sensing means associated with the main source of power for continuously determining the total amount of power being used by all of the electric power operated devices and for providing power usage level output signals representative thereof;

data storage means for receiving and averaging said power level usage output signals and providing a total power usage output signal representative of the total amount of power being used by all devices;

comparator means for producing a predetermined maximum power usage signal and comparing said total power usage signal therewith and generating power level usage control signals;

power usage level control means operatively associated with each device for receiving said power level usage control signals and for automatically reducing and increasing power available to each associated device such that the total power usage by all devices does not exceed a predetermined maximum total power usage;

reduced power usage monitoring means being effective after reduction of total power usage of the devices for repeatedly determining the amount of reduced power being used by the devices and for providing reduced power output signals representative of the amount of reduced power being used by the devices;

reduced power level control means operable by said reduced power output signals for continuously varying the amount of reduced total power available to the devices in accordance with a predetermined schedule of priority of usage by each device of reduced total power available for the system.

19. The invention as defined in claim 18 and further comprising:

calculator means for periodically calculating total power usage over a predetermined time period and adjusting the predetermined maximum power usage signal for a predetermined succeeding time period.

20. The invention as defined in claim 18 and wherein the plurality of electric power operated devices includes a plurality of electric operated space heating units located within different heating zones in the facility and further comprising:

thermostatic control means operatively associated with each of the space heating units for controlling the on-off state thereof;

temperature sensor means in each of the heating zones for generating signals representative of the temperature therein;

thermostat setting adjustment means operatively associated with said power usage control means, for automatically adjusting the temperature setting of said thermostatic control means in accordance with said power level usage control signals to reduce the temperature settings until the total power usage by all devices including the space heating units does not exceed the predetermined maximum total power usage.

21. The invention as defined in claim 20 and wherein:

said thermostat setting adjustment means being operatively associated with said reduced power usage monitoring means and constructed and arranged for incrementally reducing the temperature settings of said thermostatic control means.

22. The invention as defined in claim 21 and wherein the temperature settings of said thermostatic control means are reduced by increments of approximately 1/2°

or less.

23. The invention as defined in claim 21 wherein one of the plurality of electric power operated devices is a hot water device and further comprising:

a hot water control means for alternately turning the hot water device off and on for predetermined periods of time until the total power usage by all devices does not exceed the predetermined maximum total power usage.

24. The invention as defined in claim 23 and wherein:

said hot water control means being constructed and arranged to be operative prior to said thermostat setting adjustment means.

25. The invention as defined in any of claims 18, 19, 20, 21, 22, 23, or 24 and wherein all of the control means and all of the adjustment means are included in a micro computer device having a data display means and a user data entry means associated with each of the electric power operated devices for enabling the user to monitor and input data to the system to change the desired controlled output level of each device.

26. A continuously operable power usage control system for automatically limiting the amount of power used in a facility by a plurality of electrically operable devices, including a plurality of thermostatically controlled air conditioning devices located in separate zones in the facility and comprising:

total power usage measuring means for measuring total power usage by all the electrically operable devices and for generating total power usage signals representative of total power usage by all the electrically operable devices;

on-off control means operatively associated with each of the electrically operable devices for energizing and de-energizing the electrically operable devices;

a computer means operatively associated with said total power usage measuring means and said on-off control means for receiving the total power usage signals from said total power usage measuring means and for controlling the on-off state of said on-off control means;

a maximum total power usage setting means in said computer means for setting a maximum allowable total power usage value;

temperature sensor means in each of the separate zones and being connected to said computer means for generating temperature level signals and transmitting the temperature level signals to said computer means;

thermostatic control means in said computer means for receiving the temperature level signals and for actuating said on-off control means which are associated with the thermostatically controlled air conditioning devices when the temperature level signals indicate a temperature level in a separate zone which differs from a temperature level setting for the separate zone in said thermostatic control means;

manually operable temperature level setting means operatively associated with said thermostatic control means in said computer means for selectively manually setting desired temperature levels in the separate zones;

automatically operable temperature level setting means in said computer means for automatically changing the selectively manually set desired temperature levels in the separate zones;

comparison means in said computer means for comparing total power usage signals with the maximum allowable total power usage value and generating control signals for actuating said automatically operable temperature level setting means when total power usage by the devices exceeds the maximum allowable total power usage value whereby the selectively manually set desired temperature levels are changed to computer set temperature levels to prevent energization of the thermostatically controlled air conditioning devices until total power usage by the devices is less than the maximum allowable total power usage value.

27. The invention as defined in claim 26 and further comprising:

timer means in said computer means for controlling operation of said comparison means and causing repeated comparison of the maximum allowable total power usage value with the total power usage signals at predetermined time intervals to produce a continuing series of control signals; and

computer set temperature level change stepping means in said computer means for sequentially incrementally changing the computer set temperature levels away from the preselected manually set temperature level by predetermined incremental amounts until the maximum allowable power usage value is less than the total power usage by the devices and for reversely sequentially incrementally changing the computer set temperature levels toward the preselected manually set temperature levels without permitting the total power usage by the devices to exceed the maximum allowable power usage value.

28. The invention as defined in claim 27 and wherein:

said timer means being constructed and arranged to provide the continuing series of control signals at time intervals on the order of approximately every two seconds; and

said computer set temperature level change stepping means being constructed and arranged to change the computer set temperature levels by increments on the order of approximately 1/2°

F. or less.

29. The invention as defined in claim 28 and wherein:

one of the devices is a hot water heating device operably associated with one of said on-off control means which is operable by said computer means to prevent energization of said hot water heating device for a predetermined period of time after the total power usage by the devices exceeds the maximum allowable power usage value.

30. The invention as defined in claim 28 and wherein:

the air-conditioning devices are space heating devices; and

said manually operable temperature level setting means is constructed and arranged for manually setting a maximum temperature level and a minimum temperature level for each separate zone; and

computer set temperature level limiting means in said computer means for preventing reduction in computer set temperature levels below the manually set minimum temperature level for each separate zone.