The invention provides control of an electric load receiving power from a grid. The frequency of the grid is detected and used to determine a stress level on the grid. A high frequency detection is indicative of too little a load for the electrical power being supplied to the grid and, therefore, a
The invention provides control of an electric load receiving power from a grid. The frequency of the grid is detected and used to determine a stress level on the grid. A high frequency detection is indicative of too little a load for the electrical power being supplied to the grid and, therefore, a low stress condition. A high stress condition may exist if there is too much load for the power being supplied to the grid. Adjustment of the power consumption of the load is prevented if the high and/or low stress states is determined. If a critical high or low stress condition is determined, the load is either prevented from consuming power completely or the load is set to a maximum power consumption state, respectively. The benefits of the invention are increased if the device is combined with a load controller which operates to control power consumption based on grid frequency and a variable, which, for the particular load, is to be kept within controlled limits.
대표청구항▼
The invention claimed is: 1. A responsive load device adapted to be connected to an electric load which consumes intermittent or variable electric energy to maintain a variable of the load between upper and lower limits of the variable, the upper and lower limits of the variable being derived from
The invention claimed is: 1. A responsive load device adapted to be connected to an electric load which consumes intermittent or variable electric energy to maintain a variable of the load between upper and lower limits of the variable, the upper and lower limits of the variable being derived from and defined around a setpoint of the variable, the apparatus comprising: means for receiving an input indicative of the frequency of the mains power supplied to the load from a grid; and means responsive thereto to determine a level of stress under which the grid is operating and to control power consumption by said load in accordance with the determined stress level and to prevent the setpoint being increased or decreased in order to make power consumption be increased when a generation shortage grid stress level exceeds a first maximum threshold value and/or to prevent the setpoint being increased or decreased in order to make the power consumption be decreased when a demand shortage grid stress level is below a first minimum threshold value, wherein the device is responsive to the demand shortage grid stress level being below a second minimum threshold value, lower than the first, to increase the power consumption of the load to a maximum. 2. The device of claim 1, wherein the device is responsive to the system generation shortage grid stress level exceeding a second minimum threshold value, higher than the first, to prevent the load consuming power. 3. A responsive load device adapted to be connected to an electric load which consumes intermittent or variable electric energy to maintain a variable of the load between upper and lower limits of the variable, the upper and lower limits of the variable being derived from and defined around a setpoint of the variable, the apparatus comprising: means for receiving an input indicative of the frequency of the mains power supplied to the load from a grid; means responsive thereto to determine a level of stress under which the grid is operating and to control power consumption by said load in accordance with the determined stress level and to prevent the setpoint being increased or decreased in order to make power consumption be increased when a generation shortage grid stress level exceeds a first maximum threshold value and/or to prevent the setpoint being increased or decreased in order to make the power consumption be decreased when a demand shortage grid stress level is below a first minimum threshold value; responsive load control apparatus adapted to be connected to the electric load which consumes intermittent or variable electric energy in order to maintain a variable within the controlled upper and lower limits; means for controlling the power consumed by the load in response to the frequency of the mains power supplied to the system and the value of said variable; means for detecting the frequency of mains power supplied to the electric load and means for detecting the value of the variable of said load; means for determining the level of instantaneous stress on the grid based on the detected frequency; and wherein said means for controlling the power consumed comprises: means for comparing the detected instantaneous stress level with predetermined upper and lower instantaneous stress level thresholds, means for comparing said variable with predetermined upper and lower thresholds, means for switching off or reducing power supply to the load when said system instantaneous stress level drops below said lower instantaneous stress level limit and said variable is within the range defined by the upper and lower thresholds,and means for switching on or increasing power supplied to the load when said instantaneous stress level is above the upper instantaneous stress level limit and said variable is within the range defined by the upper and lower thresholds; and means adapted to automatically optimise or adjust the predetermined threshold values. 4. A method for controlling an electric load which receives electrical power from a grid, said electric load consuming intermittent or variable electric energy to maintain a variable between upper and lower limits of the variable, wherein the upper and lower limits are derived from and defined around a setpoint of the variable, said method comprising the steps of: determining a stress level of the grid from a frequency of the electrical power received by the electric load, preventing an increase of the setpoint when the determined stress level exceeds the predetermined maximum threshold and/or preventing a decrease of the setpoint when the determined stress level falls below the predetermined minimum threshold, and maximising the power consumed by the electric load when the determined stress level of the grid falls below a second minimum threshold, less than the first. 5. The method of claim 4, further comprising the step of: preventing the electric load from consuming power when the stress level of the grid exceeds a second maximum threshold, greater than the first. 6. The device of claim 3, wherein the device is responsive to the system generation shortage grid stress level exceeding a second minimum threshold value, higher than the first, to prevent the load consuming power. 7. The device of claim 3, wherein the device is responsive to the demand shortage grid stress level below a second minimum threshold value, lower than the first, to increase the power consumption of the load to a maximum.
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이 특허에 인용된 특허 (8)
Thomas Charles V. (c/o Virginia Power Telecommunications 104 Wilden Dr. Ashland VA 23005-9413), Air conditioning load management control system.
Aggers John R. (Apple Valley MN) Brindle Ralph C. (Minnetonka MN) Kidder Kenneth B. (Coon Rapids MN) Ullestad David C. (Brooklyn Park MN), Distributed environmental/load control system.
Elliason Kurt L. (Plymouth MN) Schnell Robert J. (Plymouth MN), Responding to pricing signals from a power supplier using mixed add/shed and profile setback delta schemes.
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