Programmable load controller
First Claim
1. A control method for minimizing during a billing period the on-peak power demand of a residential electric utility customer having an AC line and a plurality of interruptible non-priority loads and non-interruptible priority loads comprising the steps of:
- (a) defining a control point of desired power demand;
(b) shedding non-priority loads to attempt to decrease demand below the control point;
(c) providing predetermined sliding time windows;
(d) determining average energy demand of the loads over a predetermined sliding time window; and
(e) dynamically increasing said control point to a new control point when all non-priority loads have been shed and when the average power demand within the time window increases beyond said control point whereby the value of the new control point is related to the last-named average power demand.
1 Assignment
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Accused Products
Abstract
A control method and system for minimizing the on-peak power demand of a residential electric utility user having a plurality of loads is implemented by determining the average energy demand over predetermined sliding time windows and comparing them with a control point. Non-priority loads are shed in an attempt to decrease the demand below the control point. If the energy demand is still above the control point after all non-priority loads are shed, the control point is dynamically adjusted upward and no priority loads are shed. Loads are shed by transmitting bits of information to the loads when the average energy demand over the predetermined time windows increases beyond the control point. Upon receiving bits of information indicating a load should be shed, the receiver deenergizes its load. The bits of information are synchronized to the zero crossing of the AC line. The bits are transmitted simultaneously and periodically. Central load control may decrease the power demand of the user in one or more predetermined steps. A method is provided for controlling multi-phase demand where the angles between phases are not necessarily equal.
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Citations
27 Claims
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1. A control method for minimizing during a billing period the on-peak power demand of a residential electric utility customer having an AC line and a plurality of interruptible non-priority loads and non-interruptible priority loads comprising the steps of:
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(a) defining a control point of desired power demand; (b) shedding non-priority loads to attempt to decrease demand below the control point; (c) providing predetermined sliding time windows; (d) determining average energy demand of the loads over a predetermined sliding time window; and (e) dynamically increasing said control point to a new control point when all non-priority loads have been shed and when the average power demand within the time window increases beyond said control point whereby the value of the new control point is related to the last-named average power demand. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A control system for minimizing during a billing period the on-peak power demand of a residential electric utility customer having an AC line and a plurality of interruptible non-priority loads and non-interruptible priority loads comprising:
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means to define a control point of desired power demand; means coupled to said loads to shed non-priority loads to attempt to decrease demand below the control point; means to determine average energy demand of the loads over a predetermined sliding time window; and means to dynamically increase said control point to a new control point when all non-priority loads have been shed and when the average power demand within the time window increases beyond said control point whereby the value of the new control point is related to the last-named average power demand. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A load controller system for transmitting bits of information through an AC line to control a plurality of loads in which the bits of information are synchronized with the zero crossing of the AC line comprising:
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(a) means for providing an external interrupt pulse at each negative going zero crossing of the AC line; (b) timer means for counting down at a predetermined frequency asynchronously and free running with respect to the AC line and having an external interrupt window during certain counts; (c) means for disabling the external interrupt pulse at times other than the external interrupt window; and (d) means for locking the timing means onto the AC line and for reloading the timing means when an interrupt arrives during an external interrupt window whereby the countdown period of the timer means coincides with the period AC line. - View Dependent Claims (20, 21)
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22. A method for controlling power demand of a residential electric utility customer having a control point of desired power demand above which power demand cannot rise comprising the steps of:
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(a) receiving a central control signal from the utility; (b) providing a predetermined sliding time window; (c) determining the average energy demand over a predetermined sliding time window; and (d) subtracting from the average energy demand a predetermined decrement in response to said central control signal to produce a new control point. - View Dependent Claims (23, 24, 25)
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26. A method for synchronizing a transmitter of a power demand control system for a multiple phase residential electric utility customer said control system having a receiver for gating a customer load in which said receiver samples its phase at zero crossings, the synchronization being independent of the angle between the phases comprising the steps of:
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(a) transmitting from the control system a bit of control information for a half cycle of a first phase, said bit of information beginning substantially at a zero crossing of the first phase; and (b) receiving the bit of control information substantially at the zero crossing of the phase of the receiver.
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27. A load controller system coupled through an AC line to a plurality of loads having means for automatically and periodically transmitting bits of information to all the loads simultaneously comprising:
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(a) means for providing an external interrupt pulse at each negative going zero crossing of the AC line; (b) counting means initiated at the beginning of a transmission of a bit of information for determining the number of external interrupts which have occurred since the last transmission; and
,(c) means for determining when a predetermined number of external interrupts have been counted and simultaneously transmitting to all loads a further bit of information when the predetermined number of external interrupts has been counted.
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Specification