CA2115717A1 - Method and apparatus for remote control of an electrical load - Google Patents
Method and apparatus for remote control of an electrical loadInfo
- Publication number
- CA2115717A1 CA2115717A1 CA002115717A CA2115717A CA2115717A1 CA 2115717 A1 CA2115717 A1 CA 2115717A1 CA 002115717 A CA002115717 A CA 002115717A CA 2115717 A CA2115717 A CA 2115717A CA 2115717 A1 CA2115717 A1 CA 2115717A1
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- Prior art keywords
- signal
- sequence
- power
- deviations
- deviation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- 230000009467 reduction Effects 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 11
- 230000004044 response Effects 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 5
- 230000008859 change Effects 0.000 claims description 3
- 230000009471 action Effects 0.000 claims description 2
- 230000003213 activating effect Effects 0.000 claims description 2
- 230000004913 activation Effects 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 4
- 230000001186 cumulative effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 230000007257 malfunction Effects 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for AC mains or AC distribution networks
- H02J3/12—Circuit arrangements for AC mains or AC distribution networks for adjusting voltage in AC networks by changing a characteristic of the network load
- H02J3/14—Circuit arrangements for AC mains or AC distribution networks for adjusting voltage in AC networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
- H02J2310/50—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads
- H02J2310/56—The network for supplying or distributing electric power characterised by its spatial reach or by the load for selectively controlling the operation of the loads characterised by the condition upon which the selective controlling is based
- H02J2310/58—The condition being electrical
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/30—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
- Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
- Y04S20/20—End-user application control systems
- Y04S20/222—Demand response systems, e.g. load shedding, peak shaving
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Electrical Variables (AREA)
Abstract
In a method for remotely controlling the power consumption of an electrical load a switching device for controlling the supply of power to the load is responsive to preselected, deliberate signal deviations such as brownout intervals or overvoltage spikes and reduces or increases output power to the load accordingly. In a preferred embodiment a single signal deviation of a specified length or a sequence of signal deviations occurring over a specified time, or a combination of these two parameters, are used to remotely address the switching device. In this fashion, the power supplied to the load can be remotely controlled by a power utility over existing power supply mains.
Description
Field of Invention This invention relates to controllers for electrical loads. In particular, this invention relates to a method and apparatus for remotely controlling the power supplied to an electrical load through the power supply mains.
Background of the Invention Electrical power utilities typically face regular cycles of power usage requirements. Peak usage periods occur generally at predictable times during business hours, while the lowest power demand occurs late at night. Meeting energy dPm~n~s during peak periods, and disposing of excess electrical energy during low-demand periods, has long been a problem facing electrical utilities.
Many measures have been undertaken in recent years with a view to solving this problem, from educating consumers to the development and implementation of electrical or thermal storage devices which store energy acquired during low-demand periods and release it during peak periods. However, the general trends and cycles associated with electrical power usage cannot always predict usage requirements during any given period.
Moreover, generating capacity can be affected by unpredictable factors, including equipment failure, which can reduce the amount of power available during peak periods significantly below the anticipated supply.
It is therefore advantageous to an electrical utility to be able to communicate with electrical loads to control power usage in specific geographic regions, reducing power available to one region in favour of a more urgent need in another; sharing temporary power reductions between various regions; and initiating energy storage operations when demand for power is low, during so-called "free-wheeling" conditions when power consumption drops below the power capable of being produced by the utility's generators. It would be wasteful for such a system to re~uire separate conductors or other transmission means to communicate with electrical users, since all users are already connected to the utility through existing power mains. However, any such system must communicate without disrupting the mains power signal and thereby inadvertently affecting the operation of electrical loads in the system.
The present invention overcomes these problems by providing a method and apparatus for communicating with an electrical load through existing power mains.
The apparatus comprises a switching device, which may activate or deactivate the load or simply reduce or increase power to the load, responsive to signal deviations such as brownout intervals or overvoltage spikes in the supply signal. Such brownouts or spikes can be selectively delivered by the utility on demand to one or more specific geographic regions, for example a building, a city block or a larger area, and because each brownout or spike has a duration in the order of a few milliseconds the deviation from the nominal signal voltage will not adversely affect the normal operation of ordinary electrical loads.
Thus, during peak demand periods the utility can control power consumption for selected intervals and in selected regions, communicating with electrical loads through the power mains. The utility can similarly activate or increase power to energy storage devices during periods of reduced power demand, to obtain a better distribution of power consumption over the course of a daily cycle.
Summary of the Invention The present invention thus provides a method of altering the magnitude of electrical power consumption by an electrical load supplied by a supply signal carried by power supply mains, using switching means including input power means, output power means, sensing means for detecting a signal deviation in the supply signal received by the input power means, control means including a memory for recording a preselected signal deviation or sequence of signal deviations and comparing a signal deviation or sequence of signal deviations detected by the sensing means with the preselected signal deviation or sequence of signal deviations programmed into the memory, and a switch for altering the signal supplied to the load by the output power means in response to a signal deviation or sequence of signal deviations corresponding to the signal deviation or sequence of signal deviations programmed into the memory, comprising the steps of interposing the switching means between the power supply means and the load, and transmitting within the supply signal a predetermined signal deviation or sequence of signal deviations over the power supply mains to the switching means to alter the power consumption of the load.
The present invention further provides a method of altering the magnitude of electrical power consumption by an electrical load supplied by a supply signal carried by power supply mains, comprising the steps of recording in a memory a preselected signal deviation or sequence of signal deviations, monitoring the supply signal to detect a signal deviation or sequence of signal deviations, comparing the monitored signal deviation or sequence of signal deviations with the recorded signal deviation or sequence of signal deviations, and where a signal deviation or sequence of signal deviations in the supply 211~717 ._ --4 signal matches the recorded signal deviation or sequence of signal deviations, activating a switch to alter the signal supplied to the load in a predetermined fashion and thus reduce or increase the power consumption of the load.
Brief Description of the Drawings In drawings which illustrate by way of example only a preferred embodiment of the invention, Figure 1 is a block diagram of one embodiment of the switching device of the invention;
Figure 2 is a diagrammatic view of an embodiment of the switching device of the invention controlling a water heater;
Figure 3 is a schematic diagram of the power supply and signal deviation sensing means circuitry for the switching device of Figure 1;
Figure 4 is a schematic diagram of the load switching circuitry for the switching device of Figure 1;
Figure 5 is a schematic diagram of the microprocessor for the switching device of Figure 1; and Figure 6 is a graph illustrating a typical power supply profile for a metropolitan area over a weekday period of 24 hours;
Detailed Description of the Invention Figure 6 graphically illustrates an example of a typical power supply profile for a 110/220V power main over a 24 hour period during an ordinary week in a 211~717 metropolitan area. The mean supply voltage ranges from about 6% below nominal voltage during peak periods such as during business hours, to about 6% above nominal voltage during low demand periods such as late night. A
i'brownout" condition is generally considered to exist whenever the supply voltage drops 6% or more below the nominal voltage, and an overvoltage is generally considered to occur whenever the supply voltage rises to 6% or more above the nom;~l voltage. The profile of Figure 6 illustrates the many naturally occurring brownout and overvoltage intervals over the course of a typical workday.
However, signal deviations such as brownout and overvoltage conditions can also be created deliberately.
The invention takes advantage of this capability, using deliberate brownout intervals and overvoltage spikes created by a power utility on demand to communicate with a switching device 10 installed to a load at the user's premises.
The switching device 10 is used to control power to electrical devices which are capable of storing thermal energy. Some devices store thermal energy in and of themselves, for example a water heater, a refrigerator, a freezer or a thermal storage system such as a brick heater or the Air Conditioning System With Thermal Storage Cycle Control described in U.S. Patent No. 5,165,250. Other devices store thermal energy in their surrounding environment, as in the case of an ordinary baseboard or room heater, or a furnace or the like, which can superheat the environment during periods of low power demand and thus reduce the power needed to operate the device during peak periods because the temperature of the environment can be allowed to fall over time while still remaining within tolerable levels.
Similarly, an ordinary room or central air conditioner 211~717 can supercool its environment during low demand periods, and the temperature of the environment can then be allowed to rise during peak periods while still remaining within a reasonable comfort range. By interposing a switching device 10, described below, between the mains power supply and the electrical device, these electrical devices can be instantly and effectively controlled by the power utility on demand, through existing power mains. This method can significantly reduce power demands during peak periods, particularly in metropolitan areas.
A preferred embodiment of the switching means of the invention, comprising a switching device 10, is illustrated in Figures 1 through 5. The switching device 10 comprises input power means 12, output power means 14, power reduction means 16 and control means 18.
The input power means 12, illustrated schematically in Figure 3, is capable of receiving input power from an alternating current power source (not shown). This could be any alternating current power source, including a standard wall plug as found in any residential building and which derives power from the local electrical utility.
The output power means 14 is capable of providing output power from the switching device 10 to an electrical load such as a water heater, baseboard heater, air conditioner or the like.
As shown in Figure 1, in a preferred embodiment the switching device 10 further comprises power reduction means 16 electrically associated with both the power input means 12 and the power output means 14. The power reduction means 16 is operable to reduce the output power to the load device by discreet intervals.
Figure 3 illustrates the power input means comprising a power supply circuit including a bridge rectifier 50. The microprocessor 18 is stimulated to energize the power output means 14 by a zero crossing firing circuit 52, also shown in Figure 3, which serves to fire the TRIACs at the zero crossing point of the input signal and thus eliminates the effects of radio interference and surge currents, and eliminates frequency dependence because the firing circuit resets with each cycle of the input signal.
Figure 3 also illustrates a signal deviation sensor comprising a brownout detection circuit 24, which detects changes in the supply voltage and signals the microprocessor 18 when the voltage drops below a preset level, preferably 6% of the nominal supply voltage; and an overvoltage detection circuit 22 which signals the microprocessor 18 when the voltage rises above a preset limit, again preferably 6% of the nominal supply voltage.
Figure 4 illustrates the output power means 14 for the switching device 10 illustrated in Figure 1, comprising in the example shown switching circuits 14a, 14b for each of the upper and lower resistance heating elements 3, 4 of a water heater 2 as illustrated in Figure 2 for purposes of example. A low current (100 mA) opto-isolator 56 signalled by the microprocessor 18 switches a heavy duty TRIAC 58 which controls the output power to the load 2. A single switching circuit 14a or 14b will suffice for electrical devices having a single load.
Figure 6 illustrates the control means comprising a microprocessor 18 and E2PROM memory 20. The memory is programmed with an upper voltage limit representing an overvoltage condition, and a lower voltage limit representing a brownout condition. If the 211~717 supply signal reaches or exceeds either of these limits, the main task of the microprocessor 18 is engaged. This task monitors information from the signal deviation sensing means and compares this to preselected signal deviation parameters programmed into the memory 20.
For example, if a power reduction parameter programmed into the memory 20 is a sequence of two brownout intervals of 60 milliseconds each occurring over a period of 180 milliseconds, the microprocessor 18 monitoring information from the signal deviation sensing means 24 and comparing this information against the preselected power reduction parameter, will signal the output power means 14 to reduce power to the load.
The memory 20 may be programmed with any number of power reduction parameters, each of which will either deactivate the load or reduce power by a certain amount;
similarly, the memory 20 can be programmed with any number of power increase parameters, responsive to a preselected overvoltage spike or series of overvoltage spikes, to activate the load or increase power by a desired, preselected increment. Alternatively, a cumulative system can be employed whereby, for example, each time the sensing means 22 detects an overvoltage spike of exactly 7 milliseconds in duration the microprocessor 18 increases output power to the load by a specified amount, for example 10%. Cumulative power reduction can be effected in this manner as well through deliberate brownout intervals sensed by the signal deviation sensing means 24. Preferably a specific signal deviation parameter is employed to reset the switching device 10 to full output power.
The power reduction means 16 reduces the power to the load device from the maximum output level to lower output levels through conventional means such as "cycle g stealing", which entails periodically eliminating half cycles or full cycles from the alternating current being supplied to the load. In this way, both the power consumed by the load and the power supplied by the alternating current source are reduced, thereby resulting in a net reduction and savings in power consumption.
A third type of signal deviation which can be used to control power to the load is the phase angel between voltage and current. The phase angle will always change as other loads are turned on or off, but the phase angle can also be changed deliberately. Power increase and reduction parameters programmed into the memory 20 can be associated with specific changes in the phase angle between voltage and current, to actuate the switching device 10 in the same manner as brownout intervals and overvoltage spikes discussed above.
It will be appreciated that brownout intervals are created more readily than overvoltage spikes under most conditions. Accordingly, brownout intervals can be used both to increase power to (or activate) the load and decrease power to (or de-activate) the load, while overvoltage spikes would generally be used only to increase power to (or activate) the load during free-wheeling conditions, since it may be difficult to create overvoltage spikes during periods of low power supply when load reduction/de-activation would ordinarily be desirable.
The switching device 10 is programmed to be responsive to one or more specific types of signal deviations. In one case, the switching device 10 is responsive to a signal deviation of a specific predetermined duration. In the second case, the switching device 10 is responsive to a sequence of signal deviations occurring over a specific predetermined period 211~717 of time. Both of these alternatives are designed to avoid unintended switching of the load in response to a naturally occurring signal deviation.
For example, the switching device 10 can be programmed to reduce power to the load by 10% if it detects a brownout of exactly 11 ms in duration, or if it detects a series of three discrete brownout intervals over 100 ms. The latter method is less likely to result in accidental power reduction, since the chances of three discrete brownout intervals occurring naturally over 100 ms are extremely small; nevertheless, the first method will still work most of the time because of the low probability of a naturally occurring brownout of exactly the correct duration. To decrease the possibilities for accidental switching even further, these two parameters can be combined such that the switching device 10 would reduce power in response to, for example, three discrete brownout intervals of exactly 11 ms each over a period of 100 ms. The probability of this occurring naturally is so low as to be render accidental switching virtually impossible. Moreover, the brownout intervals are so short that they will not affect the operation of the load or any other electrical device connected to the same power mains. An example of a power supply profile incorporating this sequence of signal deviations is identified in Figure 6.
The switching device 10 can likewise be programmed to increase power to the load upon detecting an overvoltage spike (or brownout interval) of a specific duration, for example 10 ms, or upon detecting a specified number of discrete signal deviations over a specific period, for example three over a period of 80 ms. Again, for purposes of further reducing the possibility of accidental switching the switching device 10 may be programmed to respond only to a combination of 211~717 these two parameters, for example a sequence of two overvoltage spikes each of exactly 12 ms in duration over a period of 100 ms. An example of a power supply profile incorporating this sequence of signal deviations is identified in Figure 6.
The possible combinations are virtually limitless, the only limitations being that the duration of the signal deviation must be sufficiently short that it does not interfere with the normal operation of electrical devices which may be supplied by the affected power mains; and that the duration of a signal deviation or the number of times that it occurs over the selected period must be unlikely to occur naturally, which for purposes of the invention preferably means that there is less than a 0.05% probability that such a signal deviation or sequence of signal deviations will occur naturally. Ideally the utility will monitor the power supply profile of regions using the method, and take corrective action if a signal deviation to which the switching device 10 is programmed to respond occurs naturally.
The switching device 10 can be programmed to respond to different signal deviations or sequences of signal deviations in different ways. For example, a series of three brownout intervals over 100 ms could reduce power to the load by some specified increment, a series of four brownout intervals over 100 ms could reduce power by a different increment, and a series of five brownout intervals over the same period could shut off power completely. Alternatively, the differential switching responses can be actuated by the same number of brownout intervals where the intervals are of different lengths, or occur over different periods of time. Again, the possible combinations and permutations are virtually endless.
211~717 The switching device can also be used to activate a backup system, for example, in a water heater 2 such as that illustrated in Figure 2 which is of the type described in U.S. Patent No. 5,115,491. There are many situations, particularly in commercial uses, where major problems can arise where an element malfunctions in a hot water heater. To avoid this problem, a backup element can be employed when the primary element burns out; in Figure 2 a backup element 5 is provided to replace the upper element 3 in case of malfunction. However, there must be some means of switching from the primary element 3 to the backup element 5.
The switching device 10 can accept inputs from temperature sensors T1 and T2 associated with the heating elements 3,4 respectively. When the element is turned on the temperature must rise, and this information would be transmitted to the switching device 10. The microprocessor 18 can be programmed to monitor the temperature rise through, for example, sensor T1, and if there is no rise in temperature after a certain delay following activation of the heating element 3, the microprocessor 18 would automatically switch off the heating element 3 and activate the backup heating element 5. This system can be used as a means of switching to a backup element automatically (or on command through the method of communication described herein), and to prevent persons from tampering with the water heater 2, for example removing the sensor T1 with a view to getting more hot water. The microprocessor 18 could similarly be programmed to de-activate the elements 3, 4 when the temperature sensors T1, T2, respectively, read maximum temperature (sensor shorted out) or minimum temperature (sensor removed).
Mechanical valves can present a problem when the hot water is first turned on. Since water standing in the .
pipes will cool to room temperature, when the tap is opened the water typically comes out at higher temperatures until the valve stabilizes, which can cause scalding problems. The switching device can be programmed to monitor temperatures received from the temperature sensors T1, T2 of the upper and lower heating elements 3, 4, and a third sensor T3 placed at the output of the water heater 2. Since hot water always rises to the top of the water heater 2, the sensor with the highest temperature reading is used to control the mixing valve 6. Input from a temperature sensor T4 monitoring the temperature of the cold water supply can also be monitored by the microprocessor 18 to adjust the valve 6.
The invention having been thus described with reference to an example of a preferred embodiment, it will be obvious to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention. It will also be appreciated that the specific numbers of signal deviations, their intervals and the periods over which they may be made to occur are given as examples only and are in no way restrictive of the invention as a whole.
Background of the Invention Electrical power utilities typically face regular cycles of power usage requirements. Peak usage periods occur generally at predictable times during business hours, while the lowest power demand occurs late at night. Meeting energy dPm~n~s during peak periods, and disposing of excess electrical energy during low-demand periods, has long been a problem facing electrical utilities.
Many measures have been undertaken in recent years with a view to solving this problem, from educating consumers to the development and implementation of electrical or thermal storage devices which store energy acquired during low-demand periods and release it during peak periods. However, the general trends and cycles associated with electrical power usage cannot always predict usage requirements during any given period.
Moreover, generating capacity can be affected by unpredictable factors, including equipment failure, which can reduce the amount of power available during peak periods significantly below the anticipated supply.
It is therefore advantageous to an electrical utility to be able to communicate with electrical loads to control power usage in specific geographic regions, reducing power available to one region in favour of a more urgent need in another; sharing temporary power reductions between various regions; and initiating energy storage operations when demand for power is low, during so-called "free-wheeling" conditions when power consumption drops below the power capable of being produced by the utility's generators. It would be wasteful for such a system to re~uire separate conductors or other transmission means to communicate with electrical users, since all users are already connected to the utility through existing power mains. However, any such system must communicate without disrupting the mains power signal and thereby inadvertently affecting the operation of electrical loads in the system.
The present invention overcomes these problems by providing a method and apparatus for communicating with an electrical load through existing power mains.
The apparatus comprises a switching device, which may activate or deactivate the load or simply reduce or increase power to the load, responsive to signal deviations such as brownout intervals or overvoltage spikes in the supply signal. Such brownouts or spikes can be selectively delivered by the utility on demand to one or more specific geographic regions, for example a building, a city block or a larger area, and because each brownout or spike has a duration in the order of a few milliseconds the deviation from the nominal signal voltage will not adversely affect the normal operation of ordinary electrical loads.
Thus, during peak demand periods the utility can control power consumption for selected intervals and in selected regions, communicating with electrical loads through the power mains. The utility can similarly activate or increase power to energy storage devices during periods of reduced power demand, to obtain a better distribution of power consumption over the course of a daily cycle.
Summary of the Invention The present invention thus provides a method of altering the magnitude of electrical power consumption by an electrical load supplied by a supply signal carried by power supply mains, using switching means including input power means, output power means, sensing means for detecting a signal deviation in the supply signal received by the input power means, control means including a memory for recording a preselected signal deviation or sequence of signal deviations and comparing a signal deviation or sequence of signal deviations detected by the sensing means with the preselected signal deviation or sequence of signal deviations programmed into the memory, and a switch for altering the signal supplied to the load by the output power means in response to a signal deviation or sequence of signal deviations corresponding to the signal deviation or sequence of signal deviations programmed into the memory, comprising the steps of interposing the switching means between the power supply means and the load, and transmitting within the supply signal a predetermined signal deviation or sequence of signal deviations over the power supply mains to the switching means to alter the power consumption of the load.
The present invention further provides a method of altering the magnitude of electrical power consumption by an electrical load supplied by a supply signal carried by power supply mains, comprising the steps of recording in a memory a preselected signal deviation or sequence of signal deviations, monitoring the supply signal to detect a signal deviation or sequence of signal deviations, comparing the monitored signal deviation or sequence of signal deviations with the recorded signal deviation or sequence of signal deviations, and where a signal deviation or sequence of signal deviations in the supply 211~717 ._ --4 signal matches the recorded signal deviation or sequence of signal deviations, activating a switch to alter the signal supplied to the load in a predetermined fashion and thus reduce or increase the power consumption of the load.
Brief Description of the Drawings In drawings which illustrate by way of example only a preferred embodiment of the invention, Figure 1 is a block diagram of one embodiment of the switching device of the invention;
Figure 2 is a diagrammatic view of an embodiment of the switching device of the invention controlling a water heater;
Figure 3 is a schematic diagram of the power supply and signal deviation sensing means circuitry for the switching device of Figure 1;
Figure 4 is a schematic diagram of the load switching circuitry for the switching device of Figure 1;
Figure 5 is a schematic diagram of the microprocessor for the switching device of Figure 1; and Figure 6 is a graph illustrating a typical power supply profile for a metropolitan area over a weekday period of 24 hours;
Detailed Description of the Invention Figure 6 graphically illustrates an example of a typical power supply profile for a 110/220V power main over a 24 hour period during an ordinary week in a 211~717 metropolitan area. The mean supply voltage ranges from about 6% below nominal voltage during peak periods such as during business hours, to about 6% above nominal voltage during low demand periods such as late night. A
i'brownout" condition is generally considered to exist whenever the supply voltage drops 6% or more below the nominal voltage, and an overvoltage is generally considered to occur whenever the supply voltage rises to 6% or more above the nom;~l voltage. The profile of Figure 6 illustrates the many naturally occurring brownout and overvoltage intervals over the course of a typical workday.
However, signal deviations such as brownout and overvoltage conditions can also be created deliberately.
The invention takes advantage of this capability, using deliberate brownout intervals and overvoltage spikes created by a power utility on demand to communicate with a switching device 10 installed to a load at the user's premises.
The switching device 10 is used to control power to electrical devices which are capable of storing thermal energy. Some devices store thermal energy in and of themselves, for example a water heater, a refrigerator, a freezer or a thermal storage system such as a brick heater or the Air Conditioning System With Thermal Storage Cycle Control described in U.S. Patent No. 5,165,250. Other devices store thermal energy in their surrounding environment, as in the case of an ordinary baseboard or room heater, or a furnace or the like, which can superheat the environment during periods of low power demand and thus reduce the power needed to operate the device during peak periods because the temperature of the environment can be allowed to fall over time while still remaining within tolerable levels.
Similarly, an ordinary room or central air conditioner 211~717 can supercool its environment during low demand periods, and the temperature of the environment can then be allowed to rise during peak periods while still remaining within a reasonable comfort range. By interposing a switching device 10, described below, between the mains power supply and the electrical device, these electrical devices can be instantly and effectively controlled by the power utility on demand, through existing power mains. This method can significantly reduce power demands during peak periods, particularly in metropolitan areas.
A preferred embodiment of the switching means of the invention, comprising a switching device 10, is illustrated in Figures 1 through 5. The switching device 10 comprises input power means 12, output power means 14, power reduction means 16 and control means 18.
The input power means 12, illustrated schematically in Figure 3, is capable of receiving input power from an alternating current power source (not shown). This could be any alternating current power source, including a standard wall plug as found in any residential building and which derives power from the local electrical utility.
The output power means 14 is capable of providing output power from the switching device 10 to an electrical load such as a water heater, baseboard heater, air conditioner or the like.
As shown in Figure 1, in a preferred embodiment the switching device 10 further comprises power reduction means 16 electrically associated with both the power input means 12 and the power output means 14. The power reduction means 16 is operable to reduce the output power to the load device by discreet intervals.
Figure 3 illustrates the power input means comprising a power supply circuit including a bridge rectifier 50. The microprocessor 18 is stimulated to energize the power output means 14 by a zero crossing firing circuit 52, also shown in Figure 3, which serves to fire the TRIACs at the zero crossing point of the input signal and thus eliminates the effects of radio interference and surge currents, and eliminates frequency dependence because the firing circuit resets with each cycle of the input signal.
Figure 3 also illustrates a signal deviation sensor comprising a brownout detection circuit 24, which detects changes in the supply voltage and signals the microprocessor 18 when the voltage drops below a preset level, preferably 6% of the nominal supply voltage; and an overvoltage detection circuit 22 which signals the microprocessor 18 when the voltage rises above a preset limit, again preferably 6% of the nominal supply voltage.
Figure 4 illustrates the output power means 14 for the switching device 10 illustrated in Figure 1, comprising in the example shown switching circuits 14a, 14b for each of the upper and lower resistance heating elements 3, 4 of a water heater 2 as illustrated in Figure 2 for purposes of example. A low current (100 mA) opto-isolator 56 signalled by the microprocessor 18 switches a heavy duty TRIAC 58 which controls the output power to the load 2. A single switching circuit 14a or 14b will suffice for electrical devices having a single load.
Figure 6 illustrates the control means comprising a microprocessor 18 and E2PROM memory 20. The memory is programmed with an upper voltage limit representing an overvoltage condition, and a lower voltage limit representing a brownout condition. If the 211~717 supply signal reaches or exceeds either of these limits, the main task of the microprocessor 18 is engaged. This task monitors information from the signal deviation sensing means and compares this to preselected signal deviation parameters programmed into the memory 20.
For example, if a power reduction parameter programmed into the memory 20 is a sequence of two brownout intervals of 60 milliseconds each occurring over a period of 180 milliseconds, the microprocessor 18 monitoring information from the signal deviation sensing means 24 and comparing this information against the preselected power reduction parameter, will signal the output power means 14 to reduce power to the load.
The memory 20 may be programmed with any number of power reduction parameters, each of which will either deactivate the load or reduce power by a certain amount;
similarly, the memory 20 can be programmed with any number of power increase parameters, responsive to a preselected overvoltage spike or series of overvoltage spikes, to activate the load or increase power by a desired, preselected increment. Alternatively, a cumulative system can be employed whereby, for example, each time the sensing means 22 detects an overvoltage spike of exactly 7 milliseconds in duration the microprocessor 18 increases output power to the load by a specified amount, for example 10%. Cumulative power reduction can be effected in this manner as well through deliberate brownout intervals sensed by the signal deviation sensing means 24. Preferably a specific signal deviation parameter is employed to reset the switching device 10 to full output power.
The power reduction means 16 reduces the power to the load device from the maximum output level to lower output levels through conventional means such as "cycle g stealing", which entails periodically eliminating half cycles or full cycles from the alternating current being supplied to the load. In this way, both the power consumed by the load and the power supplied by the alternating current source are reduced, thereby resulting in a net reduction and savings in power consumption.
A third type of signal deviation which can be used to control power to the load is the phase angel between voltage and current. The phase angle will always change as other loads are turned on or off, but the phase angle can also be changed deliberately. Power increase and reduction parameters programmed into the memory 20 can be associated with specific changes in the phase angle between voltage and current, to actuate the switching device 10 in the same manner as brownout intervals and overvoltage spikes discussed above.
It will be appreciated that brownout intervals are created more readily than overvoltage spikes under most conditions. Accordingly, brownout intervals can be used both to increase power to (or activate) the load and decrease power to (or de-activate) the load, while overvoltage spikes would generally be used only to increase power to (or activate) the load during free-wheeling conditions, since it may be difficult to create overvoltage spikes during periods of low power supply when load reduction/de-activation would ordinarily be desirable.
The switching device 10 is programmed to be responsive to one or more specific types of signal deviations. In one case, the switching device 10 is responsive to a signal deviation of a specific predetermined duration. In the second case, the switching device 10 is responsive to a sequence of signal deviations occurring over a specific predetermined period 211~717 of time. Both of these alternatives are designed to avoid unintended switching of the load in response to a naturally occurring signal deviation.
For example, the switching device 10 can be programmed to reduce power to the load by 10% if it detects a brownout of exactly 11 ms in duration, or if it detects a series of three discrete brownout intervals over 100 ms. The latter method is less likely to result in accidental power reduction, since the chances of three discrete brownout intervals occurring naturally over 100 ms are extremely small; nevertheless, the first method will still work most of the time because of the low probability of a naturally occurring brownout of exactly the correct duration. To decrease the possibilities for accidental switching even further, these two parameters can be combined such that the switching device 10 would reduce power in response to, for example, three discrete brownout intervals of exactly 11 ms each over a period of 100 ms. The probability of this occurring naturally is so low as to be render accidental switching virtually impossible. Moreover, the brownout intervals are so short that they will not affect the operation of the load or any other electrical device connected to the same power mains. An example of a power supply profile incorporating this sequence of signal deviations is identified in Figure 6.
The switching device 10 can likewise be programmed to increase power to the load upon detecting an overvoltage spike (or brownout interval) of a specific duration, for example 10 ms, or upon detecting a specified number of discrete signal deviations over a specific period, for example three over a period of 80 ms. Again, for purposes of further reducing the possibility of accidental switching the switching device 10 may be programmed to respond only to a combination of 211~717 these two parameters, for example a sequence of two overvoltage spikes each of exactly 12 ms in duration over a period of 100 ms. An example of a power supply profile incorporating this sequence of signal deviations is identified in Figure 6.
The possible combinations are virtually limitless, the only limitations being that the duration of the signal deviation must be sufficiently short that it does not interfere with the normal operation of electrical devices which may be supplied by the affected power mains; and that the duration of a signal deviation or the number of times that it occurs over the selected period must be unlikely to occur naturally, which for purposes of the invention preferably means that there is less than a 0.05% probability that such a signal deviation or sequence of signal deviations will occur naturally. Ideally the utility will monitor the power supply profile of regions using the method, and take corrective action if a signal deviation to which the switching device 10 is programmed to respond occurs naturally.
The switching device 10 can be programmed to respond to different signal deviations or sequences of signal deviations in different ways. For example, a series of three brownout intervals over 100 ms could reduce power to the load by some specified increment, a series of four brownout intervals over 100 ms could reduce power by a different increment, and a series of five brownout intervals over the same period could shut off power completely. Alternatively, the differential switching responses can be actuated by the same number of brownout intervals where the intervals are of different lengths, or occur over different periods of time. Again, the possible combinations and permutations are virtually endless.
211~717 The switching device can also be used to activate a backup system, for example, in a water heater 2 such as that illustrated in Figure 2 which is of the type described in U.S. Patent No. 5,115,491. There are many situations, particularly in commercial uses, where major problems can arise where an element malfunctions in a hot water heater. To avoid this problem, a backup element can be employed when the primary element burns out; in Figure 2 a backup element 5 is provided to replace the upper element 3 in case of malfunction. However, there must be some means of switching from the primary element 3 to the backup element 5.
The switching device 10 can accept inputs from temperature sensors T1 and T2 associated with the heating elements 3,4 respectively. When the element is turned on the temperature must rise, and this information would be transmitted to the switching device 10. The microprocessor 18 can be programmed to monitor the temperature rise through, for example, sensor T1, and if there is no rise in temperature after a certain delay following activation of the heating element 3, the microprocessor 18 would automatically switch off the heating element 3 and activate the backup heating element 5. This system can be used as a means of switching to a backup element automatically (or on command through the method of communication described herein), and to prevent persons from tampering with the water heater 2, for example removing the sensor T1 with a view to getting more hot water. The microprocessor 18 could similarly be programmed to de-activate the elements 3, 4 when the temperature sensors T1, T2, respectively, read maximum temperature (sensor shorted out) or minimum temperature (sensor removed).
Mechanical valves can present a problem when the hot water is first turned on. Since water standing in the .
pipes will cool to room temperature, when the tap is opened the water typically comes out at higher temperatures until the valve stabilizes, which can cause scalding problems. The switching device can be programmed to monitor temperatures received from the temperature sensors T1, T2 of the upper and lower heating elements 3, 4, and a third sensor T3 placed at the output of the water heater 2. Since hot water always rises to the top of the water heater 2, the sensor with the highest temperature reading is used to control the mixing valve 6. Input from a temperature sensor T4 monitoring the temperature of the cold water supply can also be monitored by the microprocessor 18 to adjust the valve 6.
The invention having been thus described with reference to an example of a preferred embodiment, it will be obvious to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention. It will also be appreciated that the specific numbers of signal deviations, their intervals and the periods over which they may be made to occur are given as examples only and are in no way restrictive of the invention as a whole.
Claims (16)
1. A method of altering the magnitude of electrical power consumption by an electrical load supplied by a supply signal carried by power supply mains, using switching means including input power means, output power means, sensing means for detecting a signal deviation in the supply signal received by the input power means, control means including a memory for recording a preselected signal deviation or sequence of signal deviations and comparing a signal deviation or sequence of signal deviations detected by the sensing means with the preselected signal deviation or sequence of signal deviations programmed into the memory, and a switch for altering the signal supplied to the load by the output power means in response to a signal deviation or sequence of signal deviations corresponding to the signal deviation or sequence of signal deviations programmed into the memory, comprising the steps of interposing the switching means between the power supply means and the load, and transmitting within the supply signal a predetermined signal deviation or sequence of signal deviations over the power supply mains to the switching means to alter the power consumption of the load.
2. The method of claim 1 in which the signal deviation is a brown out interval.
3. The method of claim 1 in which the signal deviation is an overvoltage spike.
4. The method of claim 1 in which the signal deviation is a change in the phase angle between voltage and current.
5. The method of claim 1 in which the switching means is responsive to a sequence of signal deviations occurring over a preselected period of time.
6. The method of claim 1 in which the signal deviation or sequence of signal deviations programmed into the memory has a low probability of occurring naturally.
7. A method of altering the magnitude of electrical power consumption by an electrical load supplied by a supply signal carried by power supply mains, comprising the steps of recording in a memory a preselected signal deviation or sequence of signal deviations, monitoring the supply signal to detect a signal deviation or sequence of signal deviations, comparing the monitored signal deviation or sequence of signal deviations with the recorded signal deviation or sequence of signal deviations, and where a signal deviation or sequence of signal deviations in the supply signal matches the recorded signal deviation or sequence of signal deviations, activating a switch to alter the signal supplied to the load in a predetermined fashion and thus reduce or increase the power consumption of the load.
8. The method of claim 7 in which the signal deviation is a brownout interval.
9. The method of claim 7 in which the signal deviation is an overvoltage spike.
10. The method of claim 7 in which the signal deviation is a change in the phase angle between voltage and current.
11. The method of claim 7 in which the sequence of signal deviations occurs over a preselected period of time.
12. The method of claim 7 in which different signal deviations or sequences of signal deviations correspond to different specific output power reductions or increases to the load.
13. The method of claim 7 including the step of monitoring the power supply mains and taking corrective action when a preselected signal deviation or sequence of signal deviations occurs naturally.
14. An apparatus for controlling a water heater, comprising output power means for actuating heating elements in the water heater or a solenoid mixing valve controlling hot water output, or both, and a microprocessor responsive to inputs from temperature senors associated with the heating elements, whereby following activation of a heating element the microprocessor monitors the temperature sensor associated with that heating element to determine whether the temperature of that element is increasing, and if the temperature is not increasing switches output power to an alternate element.
15. The apparatus of claim 14, including a temperature sensor associated with a hot water output of the water heater, whereby the microprocessor activates the heating elements or mixing valve according to the highest temperature input by the temperature sensors.
16. The apparatus of claim 14, including a temperature sensor associated with a cold water supply, whereby the microprocessor adjusts the mixing valve in response to inputs from the temperature sensors to maintain a hot water output at a constant temperature.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002115717A CA2115717A1 (en) | 1994-02-15 | 1994-02-15 | Method and apparatus for remote control of an electrical load |
| AU17026/95A AU1702695A (en) | 1994-02-15 | 1995-02-15 | Method and apparatus for remote control of an electrical load |
| PCT/CA1995/000077 WO1995022190A1 (en) | 1994-02-15 | 1995-02-15 | Method and apparatus for remote control of an electrical load |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002115717A CA2115717A1 (en) | 1994-02-15 | 1994-02-15 | Method and apparatus for remote control of an electrical load |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2115717A1 true CA2115717A1 (en) | 1995-08-16 |
Family
ID=4152918
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002115717A Abandoned CA2115717A1 (en) | 1994-02-15 | 1994-02-15 | Method and apparatus for remote control of an electrical load |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU1702695A (en) |
| CA (1) | CA2115717A1 (en) |
| WO (1) | WO1995022190A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008048046A1 (en) * | 2008-09-19 | 2010-04-08 | Siemens Aktiengesellschaft | Apparatus and method for operating an electrical load |
| EP2506382A2 (en) | 2011-03-28 | 2012-10-03 | Siemens Aktiengesellschaft | Method and device for supplying electrical energy |
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| US5812422A (en) * | 1995-09-07 | 1998-09-22 | Philips Electronics North America Corporation | Computer software for optimizing energy efficiency of a lighting system for a target energy consumption level |
| DE19606488A1 (en) * | 1996-02-22 | 1997-08-28 | Hey Tec Regelungstechn Gmbh | Electromagnetic or electronic switch and its use in a switch distributor |
| DE19718160A1 (en) * | 1997-04-29 | 1998-11-05 | Siemens Ag | Microprocessor control device with undervoltage protection |
| US20110182094A1 (en) * | 2007-08-13 | 2011-07-28 | The Powerwise Group, Inc. | System and method to manage power usage |
| US8340833B2 (en) * | 2010-03-31 | 2012-12-25 | General Electric Company | Control distribution transformer and method of making same |
| US8102148B2 (en) | 2010-03-31 | 2012-01-24 | General Electric Company | Augmented distribution transformer and method of making same |
| US9263182B2 (en) | 2010-03-31 | 2016-02-16 | General Electric Company | Control distribution transformer and method of making same |
| US8973212B2 (en) | 2011-03-03 | 2015-03-10 | G.B.D. Corp. | Filter housing construction for a surface cleaning apparatus |
| US8869345B2 (en) | 2011-03-03 | 2014-10-28 | G.B.D. Corp. | Canister vacuum cleaner |
| US8973214B2 (en) | 2011-03-03 | 2015-03-10 | G.B.D. Corp. | Cyclone chamber and dirt collection assembly for a surface cleaning apparatus |
| US9101252B2 (en) | 2011-03-03 | 2015-08-11 | G.B.D. Corp. | Configuration of a surface cleaning apparatus |
| US8978198B2 (en) | 2011-03-03 | 2015-03-17 | G.B.D. Corp. | Filter housing for a surface cleaning apparatus |
| US8646149B2 (en) | 2011-03-03 | 2014-02-11 | G.B.D. Corp. | Filter housing construction for a surface cleaning apparatus |
| US9962052B2 (en) | 2011-03-04 | 2018-05-08 | Omachron Intellectual Property Inc. | Surface cleaning apparatus |
| US8659184B2 (en) | 2011-03-04 | 2014-02-25 | G.B.D. Corp. | Method and apparatus for powering an appliance |
| US11445872B2 (en) | 2014-12-17 | 2022-09-20 | Omachron Intellectual Property Inc. | Surface cleaning apparatus |
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| US11452409B2 (en) | 2014-12-17 | 2022-09-27 | Omachron Intellectual Property Inc. | Surface cleaning apparatus |
| US11745190B2 (en) | 2019-01-23 | 2023-09-05 | Omachron Intellectual Property Inc. | Surface cleaning apparatus |
| US12075966B2 (en) | 2021-08-05 | 2024-09-03 | Omachron Intellectual Property Inc. | Household appliance having an improved cyclone and a cyclone for same |
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|---|---|---|---|---|
| US4413189A (en) * | 1981-11-09 | 1983-11-01 | Bottom Jr Dudley | Demand reduction system for regulated electric utility distribution circuits |
| DE3212765C2 (en) * | 1982-04-06 | 1986-02-20 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Method and arrangement for power control |
| US4978833A (en) * | 1989-01-27 | 1990-12-18 | Bunn-O-Matic Corporation | Hot water dispenser having improved water temperature control system |
| US5168170A (en) * | 1989-09-07 | 1992-12-01 | Lexington Power Management Corporation | Subscriber electric power load control system |
| US5115491A (en) * | 1990-12-17 | 1992-05-19 | Maier Perlman | Tempering system for storage tank water heaters utilizing inlet and outlet heat exchanger |
| WO1992016041A1 (en) * | 1991-03-04 | 1992-09-17 | Econolight Limited | Electrical power distribution control system |
| US5481140A (en) * | 1992-03-10 | 1996-01-02 | Mitsubishi Denki Kabushiki Kaisha | Demand control apparatus and power distribution control system |
| EP0647365B1 (en) * | 1992-09-01 | 1998-10-07 | DOSANI, Nazir | Power controller device |
| IT1256105B (en) * | 1992-11-12 | 1995-11-28 | Valerio Narduzzo | CONSUMPTION MANAGEMENT AND CONTROL DEVICE, PARTICULARLY FOR CIVIL ELECTRICAL SYSTEMS |
-
1994
- 1994-02-15 CA CA002115717A patent/CA2115717A1/en not_active Abandoned
-
1995
- 1995-02-15 AU AU17026/95A patent/AU1702695A/en not_active Abandoned
- 1995-02-15 WO PCT/CA1995/000077 patent/WO1995022190A1/en active Application Filing
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008048046A1 (en) * | 2008-09-19 | 2010-04-08 | Siemens Aktiengesellschaft | Apparatus and method for operating an electrical load |
| EP2506382A2 (en) | 2011-03-28 | 2012-10-03 | Siemens Aktiengesellschaft | Method and device for supplying electrical energy |
| DE102011006214A1 (en) | 2011-03-28 | 2012-10-04 | Siemens Aktiengesellschaft | Method and device for electrical power supply |
Also Published As
| Publication number | Publication date |
|---|---|
| AU1702695A (en) | 1995-08-29 |
| WO1995022190A1 (en) | 1995-08-17 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |