System for monitoring and controlling electric power consumption

• US 4,216,384 A
• Filed: 12/09/1977
• Issued: 08/05/1980
• Est. Priority Date: 12/09/1977
• Status: Expired due to Term

• Current Assignee: Directed Energy Systems Incorporated
• Original Assignee: Directed Energy Systems Incorporated
• Inventors: Hurley, Frederick A.
• Primary Examiner(s): Hix, L. T.
• Assistant Examiner(s): Schreyer, S. D.
• Application Number:
  US05/859,099
• Time in Patent Office: 970 Days
• Field of Search: 307/39, 307/41, 307/38, 307/62, 324/103 R
• US Class Current: 307/39
• 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 3/144 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 is disclosed for monitoring and controlling the consumption of electrical energy and the peak demand for electrical power in an installation. The system can be programmed to automatically limit the instantaneous power consumption of the installation in accordance with the time of day and the required need of the facility. The system sheds appropriate individual loads when the total instantaneous power consumption exceeds the pre-selected set point applicable for the time in question, to thereby return the power consumption of the installation to within this allowable limit. Provision is made for selective load shedding whereby the relative size of the load shed corresponds with the relative degree of power overdraw. In addition, after each shedding event, the system automatically realigns the order of priority by which the loads are shed. Furthrmore, all shed loads are automatically reset to an operative condition on a periodic basic, according to the operating requirements of each load.

Claims

1. A system for monitoring and controlling the electrical amperage draw of an installation supplied by an electrical supply line, said installation having therein a number of individual loads to be controlled, said loads being supplied by respective load lines, and for decreasing the instantaneous amperage draw of the installation to within a pre-selected allowable maximum whenever the amperage draw exceeds that maximum, comprising:

supply line sensing means magnetically coupled to the electrical supply line for generating a supply line sensing signal proportional to the amperage flowing in the supply line;

allowable load set point programming means for selecting the maximum allowable amperage draw, and for receiving the supply line sensing signal from the supply line sensing means, to generate an overdraw signal whenever the amperage flowing in the supply line exceeds the allowable maximum;

period programming means for generating a time signal at pre-selected intervals and means responsive to said time signal for causing said allowable load set point programming means to change the maximum allowable amperage draw to a new pre-selected value;

individual load sensing means magnetically coupled to each of the load lines for generating a load sensing signal for each individual load to indicate whether the individual load is operating;

control means for receiving the overdraw signal from the allowable load set point programming means and the load sensing signals from the individual load sensing means, and for generating a shed signal directing the shedding of a particular one of the operating individual loads so as to decrease the electrical amperage draw of the installation; and

shed means electrically connected to the individual loads for receiving the shed signal from the control means and for disconnecting the particular individual load.

2. A system according to claim 1 wherein said means responsive to said time signal forms a part of said allowable load set point programming means.

3. A system for monitoring and controlling the electrical amperage draw of an installation supplied by an electrical supply line, said installation having therein a number of individual loads to be controlled, said loads being supplied by respective load lines, and for decreasing the instantaneous amperage draw of the installation to within a pre-selected allowable maximum whenever the amperage draw exceeds that maximum, comprising:

supply line sensing means magnetically coupled to the electrical supply line for generating a supply line sensing signal proportional to the amperage flowing in the supply line;

allowable load set point programming means for selecting the maximum allowable amperage draw, and for receiving the supply line sensing signal from the supply line sensing means, to generate an overdraw signal whenever the amperage flowing in the supply line exceeds the allowable maximum;

period programming means for generating a time signal at pre-selected intervals, and means responsive to said time signal for causing said allowable load set point programming means to change the maximum allowable amperage draw to a new pre-selected value;

individual load sensing means magnetically coupled to each of the load lines for generating a load sensing signal for each individual load to indicate whether the individual load is operating;

relative load connection means for connecting the load line of each individual load into one of a number of relative groupings according to the amount of amperage drawn by said load;

relative overdraw sensing means responsive to the selected maximum allowable amperage and to the supply line sensing signal for generating a further overdraw signal whenever the amperage flowing in the supply line exceeds the selected maximum allowable amperage by more than a pre-selected overdraw value;

control means for receiving the overdraw signal from the allowable load set point programming means and the load sensing signals from the individual load sensing means, and for generating a shed signal directing the shedding of one of the operating individual loads so as to decrease the electrical amperage draw of the installation;

relative load control means responsive to said further overdraw signal and to the relative connection of the load lines for directing the shed signal generated by the control circuit so as to cause the shedding of a load in the grouping having an amperage draw corresponding relatively to the amount by which the amperage flowing in the supply line exceeds the selected maximum allowable amperage; and

shed means electrically connected to the individual loads for receiving the shed signal from the relative load control means, and for disconnecting the particular individual load.

4. A system according to claim 3 wherein said relative load connection means forms part of said individual load sensing means, said relative overdraw sensing means forms part of said allowable load set point programming means, and said relative load control means forms part of said control circuit.

5. A system according to claim 3, further comprising sequential load reset means for periodically returning to an operative status all individual loads then disconnected as a result of any previous shed signal, the returning to operative status of more than one load taking place on a sequential time-delayed basis.

6. A system according to claim 5 wherein said sequential load reset means includes means for selectively resetting individual loads at different periodic intervals.

7. A system according to claim 6, further comprising shed priority alignment means responsive to the shed signal from said control means for automatically realigning the order in which the individual loads in each grouping will be shed upon the occurrence of the next shed signal from the control means.

8. A system according to claim 7, further comprising shed priority alignment means responsive to the shed signal from said control means for automatically realigning the order in which selected individual loads in each grouping will be shed upon the occurrence of the next shed signal from the control means, while maintaining the remaining non-selected individual loads last in order of shedding priority in each grouping.

9. A system for monitoring and controlling the electrical amperage draw of an installation supplied by an electrical supply line, said installation having therein a number of individual loads to be controlled, said loads being supplied by respective load lines, and for decreasing the instantaneous amperage draw of the installation to within a pre-selected allowable maximum whenever the amperage draw exceeds that maximum, comprising:

supply line sensing means magnetically coupled to the electrical supply line for generating a supply line sensing signal proportional to the amperage flowing in the supply line;

allowable load set point programming means for selecting the maximum allowable amperage draw, and for receiving the supply line sensing signal from the supply line sensing means, to generate an overdraw signal whenever the amperage flowing in the supply line exceeds the allowable maximum;

period programming means for generating a time signal at pre-selected intervals, and means responsive to said time signal for causing said allowable load set point programming means to change the maximum allowable amperage draw to a new pre-selected value;

individual load sensing means magnetically coupled to each of the load lines for generating a load sensing signal for each individual load to indicate whether the individual load is operating;

relative load connection means for connecting the load line of each individual load into one of two groupings, a first grouping for loads having an amperage draw above some selected load value, and a second grouping for loads having an amperage draw below the selected load value;

relative overdraw sensing means responsive to the selected maximum allowable amperage and to the supply line sensing signal for generating a second overdraw signal whenever the amperage flowing the the supply line exceeds the selected maximum allowable amperage by more than a pre-selected overdraw value;

control means for receiving the overdraw signal from the allowable load set point programming means and the load sensing signals from the individual load sensing means, and for generating a shed signal directing the shedding of one of the operating individual loads so as to decrease the electrical amperage draw of the installation;

relative load control means responsive to the second overdraw signal and to the relative connection of the load lines, for directing the shed signal generated by the control circuit so as to cause the shedding of a load in the first grouping of loads whenever the excess amperage flowing in the supply lines is greater than the pre-selected overdraw value, and to cause the shedding of a load in the second grouping when the excess amperage flowing in the supply line is less than the pre-selected overdraw value; and

shed means electrically connected to the individual loads for receiving the shed signal from the relative load control means and for disconnecting the particular individual load.

10. A system according to claim 9 wherein said relative load connection means forms part of said individual load sensing means, said relative overdraw sensing means forms part of said allowable load set point programming means, and said relative load control means forms part of said control circuit.

11. A system for monitoring and controlling the electrical amperage draw of an installation supplied by an electrical supply line, said installation having therein a number of individual loads to be controlled, said loads being supplied by respective load lines, and for decreasing the instantaneous amperage draw of the installation to within a pre-selected allowable maximum whenever the amperage draw exceeds that maximum, comprising:

supply lines sensing means magnetically coupled to the electrical supply line for generating a supply line sensing signal proportional to the amperage flowing in the supply line;

allowable load set point programming means for selecting the maximum allowable amperage draw, and for receiving the supply line sensing signal from the supply line sensing means, to generate an overdraw signal whenever the amperage flowing in the supply line exceeds the allowable maximum;

period programming means for generating a time signal at pre-selected intervals and means responsive to said time signal for causing said allowable load set point programming means to change the maximum allowable amperage draw to a new pre-selected value;

individual load sensing means magnetically coupled to each of the load lines for generating a load sensing signal for each individual load to indicate whether the individual load is operating;

control means for receiving the overdraw signal from the allowable load set point programming means and the load sensing signals from the individual load sensing means, and for generating a shed signal directing the shedding of a particular one of the operating individual loads so as to decrease the electrical amperage draw of the installation;

shed means electrically connected to the individual loads for receiving the shed signal from the control means and for disconnecting the particular individual load; and

sequential load reset means for periodically returning to an operative status all individual loads then disconnected as a result of any previous shed signal, the returning to operative status of more than one load taking place on a sequential time-delayed basis.

12. A system according to claim 11 wherein said sequential load reset means includes means for selectively re-setting individual loads at different periodic intervals.

13. A system according to claim 12, further comprising shed priority alignment means responsive to the shed signal from said control means for automatically realigning the order in which the individual loads will be shed upon the occurrence of the next shed signal from the control means.

14. A system according to claim 12, further comprising shed priority alignment means responsive to the shed signal from said control means for automatically realigning the order in which selected individual loads will be shed upon the occurrence of the next shed signal from the control means, while maintaining the remaining non-selected individual loads last in order of shedding priority.

15. A system for monitoring and controlling the electrical amperage draw of an installation supplied by an electrical supply line, said installation having therein a number of individual loads to be controlled, comprising:

a supply line sensor coupled to the electrical supply line for generating a supply line sensing signal proportional to the amperage flowing in the supply line;

an allowable load set point indicator for designating the maximum allowable amperage draw, and for receiving said supply line sensing signal from said supply line sensor, to generate an overdraw signal whenever the amperage flowing in the supply line exceeds the maximum allowable amperage draw;

control means for receiving the overdraw signal from said allowable load set point indicator for generating a shed signal directing the shedding of particular individual loads so as to decrease the electrical amperage draw of the installation;

a load shedding circuit electrically connectable to the individual loads for receiving said shed signal from said control means and for disconnecting said particular individual loads, said load shedding circuit including a shed priority control circuit for changing the shedding sequence of the individual loads on different shed cycles following occurrence of said overdraw signal; and

a timer for controlling the period during which individual loads are shed, said timer being connected to said load shedding circuit for re-connecting individual loads after being disconnected for predetermined time intervals to thereby create an overdraw to initiate a new shed cycle and the shedding of a different load.

16. A system for monitoring and controlling the electrical amperage draw of an installation supplied by an electrical supply line, said installation having therein a number of individual loads to be controlled, comprising:

a supply line sensor coupled to the electrical supply line for generating a supply line sensing signal proportional to the amperage flowing in the supply line;

an allowable load set point indicator for designating the maximum allowable amperage draw, and for receiving said supply line sensing signal from said supply line sensor, to generate an overdraw signal whenever the amperage flowing in the supply line exceeds the maximum allowable amperage draw;

control means for receiving the overdraw signal from said allowable load set point indicator for generating a shed signal directing the shedding of particular individual loads so as to decrease the electrical amperage draw of the installation;

a load shedding circuit electrically connectable to the individual loads for receiving said shed signal from said control means and for disconnecting said particular individual loads;

a timer for controlling the period during which individual loads are shed, said timer being connected to said load shedding circuit for re-connecting individual loads after being disconnected for predetermined time intervals;

period programming means for generating a time signal at pre-selected intervals;

and means responsive to said time signal for causing said allowable load set point indicator to change the maximum allowable amperage drawn to a new pre-selected value.

17. The system according to claim 16 wherein said load shedding circuit further includes a shed priority control circuit for changing the shedding sequence of the individual loads on different shed cycles following occurrence of said overdraw signal.

18. The system according to claim 17 wherein said shed priority control circuit has a shed priority sequence wherein certain pre-selected individual loads are always shed last.