Patent Application
20110054707
The present disclosure relates generally to the field of building electrical systems and more specifically to building generation systems including utility power sources and standby power sources. Standby power systems are generally configured to provide backup power to electrical loads having the highest priority in the event of a utility source failure. The cost of electricity provided by utility sources can vary by the day, hour, or minute depending on the cost of the fuel source and the amount of power being consumed.
One exemplary embodiment relates to a control system for a home generator. The control system includes circuitry configured to determine a first cost of electricity provided by an off-site provider, determine a second cost of electricity produced by the home generator, compare the first cost with the second cost, and provide the result of the comparison as an output.
Another exemplary embodiment relates to a method of controlling a home generator. The method includes determining a first cost of electricity provided by an off-site provider, determining a second cost of electricity produced on-site, comparing the first cost of electricity to the second cost of electricity, and using the result of the comparison to decide whether to operate the home generator to produce electricity instead of using the electricity provided by the off-site provider.
Another exemplary embodiment relates to a home electricity system. The home electricity system includes a circuit breaker panel coupled to a number of electrical loads, a transfer switch coupled to the circuit breaker panel, a power line coupled to the transfer switch and configured to provide electricity from a utility provider, an engine-generator-set coupled to the transfer switch, and a control system. The control system is configured to determine a first cost of electricity provided by the utility provider, determine a second cost of electricity produced on-site, and compare the first cost with the second cost and provide the result of the comparison as an output.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.
These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.
According to various exemplary embodiments, the standby generator of a building may be used to supplement or replace an off-site utility power source and allow for the consumer to power appliances for a lower cost than the utility power provider. A cost per kWh (e.g., real time cost, cost as a function of time of day, cost as a function of usage, etc) can be provided to the consumer so they know which appliances are more cost effective to operate under standby power rather than prime or utility power. The consumer can decrease energy costs by running electrical loads (e.g., appliances) off of a secondary source of power (e.g., a generator), rather than the primary off-site utility source when it would be more cost effective to do so. This approach puts consumers in more control of the overall cost of electricity.
Generator 108 and distribution panel 104 are also coupled to a transfer switch 112 (e.g., a cost comparison transfer switch) and a distributional subpanel 114 (e.g., a cost comparison subpanel). Distribution panel 104 may route power for some loads 116 through transfer switch 112 and subpanel 114. Transfer switch 112 is configured to determine the most cost effective power source between the generator 108 and the utility source provided via meter 102. If the cost to power loads 116 would be less if the power were provided by generator 108, then transfer switch 112 may route power for loads 116 through subpanel 114 from generator 108 rather than from meter 102. Alternatively, if the cost to power loads 116 would be less if the power were provided from meter 102, then transfer switch 112 may route power for loads 116 from meter 102 rather than from generator 108.
Transfer switch 112 may receive signals representing cost data for comparison purposes from various sources. According to one exemplary embodiment, transfer switch 112 may receive a signal representing utility cost data (e.g., electricity, natural gas for generator 108, etc.) over the utility line using power line carrier (PLC) technology. According to another exemplary embodiments, transfer switch 112 may receive a signal representing utility cost data from a wireless network of the utility, for example a cellular network or wireless transmitters/transceivers installed on meter 102, on power line poles, on power line transformers, on power line crossovers, or on other utility locations. According to still other exemplary embodiments, transfer switch 112 may retrieve a signal representing utility cost data from a computer (e.g., a personal computer) via the Internet, from a database stored in transfer switch 112 or stored in a coupled computer, from an electronic bill, or from user entered data.
Transfer switch 112 may compare the costs of providing power from meter 102 or from generator 108 by calculating a difference in therm ratio. The signals representing cost data received by transfer switch may include the price per therm or price per British thermal unit (BTU) for the power source. Transfer switch 112 may also receive a signal representing data about loads 116 coupled to transfer switch 112 and subpanel 114 (e.g., from a database, from user entry, from loads 116), for example, the therm or BTU usage of the load per kilowatt-hour (kWh). From these signals (e.g., representing cost data and power usage), transfer switch 112 may calculate the price per kWh that loads 116 would use at a particular time for the power source. Thus for any given time period or over preprogrammed time intervals, transfer switch 112 may compare whether it would cost less to provide power to loads 116 from meter 102 or from generator 108. For example, transfer switch 112 may compare costs about every hour, about every 30 minutes, about every ten minutes, about every 5 minutes, about every minute, etc.
For example, a 15 kW generator at half load may use 126,000 BTU/hr of natural gas. The utility company may charge $0.5161 per therm of natural gas in a given month and charge $0.22 per kWh at peak time for electricity. Transfer switch 112 receives a signal representing each of these costs. Given that one therm is about equal to 100,000 BTUs of natural gas, transfer switch 112 determines that a resident running at 7.5 kWh would pay:
Transfer switch 112 may compare these prices per hour usage to determine a difference of about $1.00 per hour usage of the 7.5 kW load 116 by operating generator 108 with natural gas instead of off-site electric power loads 116. Transfer switch 112 may then operate generator 108 to power load 116 and disconnect power from the off-site source for load 116.
According to various exemplary embodiments, generator 108 may be a home standby generator, a portable generator, or a generator capable of being used by another type of building. According to some exemplary embodiments generator 108 may be powered by natural gas or propane, while according to other exemplary embodiments, generator 108 may be powered by another fuel source such as gasoline. It is noted that while the illustrated exemplary embodiment shows the use of a generator in combination with a utility power source, different configurations are possible. According to some exemplary embodiments, generator 108 may be substituted by a solar, wind, geothermal, or other non-utility or standby power sources. According to other exemplary embodiments, electrical system 100 may include additional standby power sources (e.g., generator, solar, geothermal, etc.) or an additional utility power source that may be used to provide power instead of or in addition to the power provided by generator 108 and meter 102 depending on the cost comparison performed by subpanel 114.
Meter 102, generator 108, and transfer switch 110 are all shown as being mounted exterior of a building (e.g., on the exterior wall or on the ground) while distribution panel 104, transfer switch 112, and subpanel 114 are shown mounted on the interior of the building (e.g., on a basement wall). It is noted that according to other exemplary embodiments, meter 102 and transfer switch 110 may be mounted in the interior of the building or one or more of distribution panel 104, transfer switch 112, and subpanel 114 may be mounted exterior to the building.
While transfer switch 110 is illustrated as being separate from distribution panel 104, it is noted that according to other exemplary embodiments, transfer switch 110 may be integral with distribution panel 104. Referring also to
According to various exemplary embodiments, controller 418 may be any digital or analog control logic or hardware capable of controlling transfer of power between generator 108 and meter 102, capable of controlling startup and communication with generator 108, capable of receive signals representing costs of power sources, and capable of comparing cost and load data to determine whether it would be more cost effective to power loads 116 using generator 108 or using off-site electricity via meter 102. According to some exemplary embodiments, controller 418 could output indicators of cost savings, cost usage of loads 116, and/or power usage of loads 116 to a display, a computer, an email account, a mobile or cellular phone, etc. While controller 418 is illustrated as being mounted in transfer switch 112, according to other exemplary embodiments, controller 418 could mounted at other locations, for example on generator 108, on subpanel 114, on a remotely located computer, etc. Load lines (L1 and L2) providing power to subpanel 114 are coupled to transfer switch 112 via a load connection 426.
While transfer switch 112 is illustrated as being separate from subpanel 114, it is noted that according to other exemplary embodiments, transfer switch 112 may be integral with subpanel 114. Referring also to
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While the exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications. The order or sequence of any processes or method steps may be varied or re-sequenced according to alternative embodiments.
The present application contemplates methods, systems and program products on any machine-readable media for accomplishing its operations. The embodiments of the present application may be implemented using existing computer processors or logic controllers, or by a special purpose computer processor or logic controller for an appropriate system, incorporated for this or another purpose or by a hardwired system.
It is important to note that the construction and arrangement of the control system and home electricity system shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter. For example, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.
As noted above, embodiments within the scope of the present application include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media which can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.
It should be noted that although the figures herein may show a specific order of method steps, it is understood that the order of these steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. It is understood that all such variations are within the scope of the application. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.
