The present disclosure relates generally to a system and method for managing utility consumption. More particularly it relates to a system and method for monitoring and controlling peak demand for a utility.
Utility consumption often has costs above and beyond the flat rate paid for a unit of utility consumption. For example, during hot weather, electrical utility grids are overburdened by heavy air conditioner usage. When brownouts occur, electric motors and other equipment may be damaged. In order to have reserves available for periods of peak demand, utility companies build new plants or upgrade older plants to provide additional electric power generating capacity.
The costs incurred by the utility companies are passed on to consumers in the form of higher rates or surcharges. Utilities may include electricity, natural gas, chilled water, steam, and compressed air. Rate schedules for utilities may be set with two components, a flat rate for consumption, and an additional charge based on peak demand. Sometimes the additional charge to the consumer based on peak demand can amount to up to one-half of the total utility cost, even if the peak consumption accounts for only 10% of the entire consumption.
Accordingly, a system, method, and apparatus are disclosed for managing utility consumption. Also disclosed is an embodiment for reducing peak demand for a utility by staggering requests for that utility. In yet another embodiment, sensors monitor utility consumption throughout a facility. Those items of equipment not in active use, but still drawing utility resources, are shut down after a predetermined interval. In still another embodiment, storage and conversion technologies are used to offset peak demand and the associated peak demand costs.
Referring to the exemplary drawings wherein like elements are numbered alike in the several FIGURES:
As discussed above, additional charges accrue for peak utility consumption. The system, method, and apparatus according to an embodiment disclosed herein may operate continuously or may manage utility consumption when particular criteria are met. These criteria may comprise: high utility consumption, growing utility consumption (i.e., utility consumption trending upward), scheduled utility consumption, or other causes. Scheduling of utility consumption may occur to meet conditions that vary with production plans, quality goals, or time of day.
It will be appreciated that the system, method, and apparatus disclosed herein has wide applicability, whether in a domestic (household) environment or in a manufacturing, governmental, educational, or other institutional or commercial environment.
Management of utility consumption may be formulated within the context of utility consumption optimization. Referring to the high level flow chart of
In a step 102, an optimization horizon over which substantially to optimize decisions about utility consumption is identified. By optimization horizon is meant a period of time over which the optimization is planned. This optimization horizon could be fixed. (e.g., always look 1 minute ahead), or could be dynamically adjusted and updated as conditions warrant. The advantage of this latter approach is that it is possible to identify a minimal optimization horizon such that the first decision will be substantially optimal despite end-of-study effects. The shorter the optimization horizon, the quicker it may be to find a substantially optimal solution.
In a step 104, an objective function to be optimized is identified. This may be a function to be minimized, such as peak utility demand, or a function to be maximized, for example, quality production rate. The objective function may even be a combination, e.g., a joint function of both peak demand and quality production rate.
In step 106, likely utility draws and their sources over this horizon are identified. Likely utility draws may be known from production planning data and schedules, for example. They may also be known from ambient conditions such as outdoor temperature or time of day.
In step 108, constraints on a utility draw schedule may be identified. These constraints may comprise, e.g., that utility draw A occur before utility draw B, or that utility draws C and D occur simultaneously.
There may be a step 110 in which magnitudes and durations of utility draws based on historical information are identified. For example, it may be known that weld gun A4, say, draws 230 watts of electrical power for 3 seconds. Step 110 may also comprise identifying magnitudes and durations of utility draws based on current information. For example, it may be known that a particular cutter tool is worn, and until replaced, requires 50% more electrical power than average. Furthermore, step 110 may also include identifying a time-varying signature or profile of a utility draw, such as a sudden initial spike at the start of a utility draw.
In a step 112 an optimization algorithm is applied to the problem thus constructed. One approach that may be used in an optimization algorithm is to model each utility draw as an independent agent and employ a Fictitious Play based algorithm to coordinate their behavior to minimize total consumption within performance constraints. Another possible approach is simply to adapt a commercial scheduling optimization package, such as those used for logistics planning. Another approach that may be used is to apply a simulated annealing optimization algorithm to the constrained problem. Yet another approach may utilize a genetic algorithm for optimization.
The optimization algorithm may be stopped 114 when a stopping criterion is met. Such a criterion may be, e.g., a time limit, an iteration limit, a user interrupt, or some other stopping criterion. Note that it is also possible to dynamically modify an optimization algorithm that is continuously running. In such an embodiment, the system and method may perturb the current best solution through the addition of new information.
The result of employing the optimization algorithm is a substantially optimal strategy for utility consumption. As was stated above, a strategy is a coordination of utility draws by the loads under management by the system, method, and apparatus so as to achieve substantially optimal utility consumption within the constraints identified. In an embodiment to be discussed further below in connection with
The next step 116 is to apply the substantially optimal strategy developed by usage of the algorithm. The optimization algorithm may be re-run, and its resultant substantially optimal strategy applied in an iterative fashion 118 to allow for continual update as conditions change or new situations arise.
Referring to
Devices consuming units of utility consumption are generally referred to herein as loads. Loads draw units of utility consumption in parallel, in general, as shown at 208, 210, and 212. In the embodiment shown in
Although shown with switch 214 interposed between supply 202 and sensor 216, this particular order may be changed, so that sensor 216 is interposed between supply 202 and switch 214.
Switch 214 may function to register user input for load activation. The user attempt to activate the load is then passed to a computing device 230 as an input to the utility management algorithm. Alternatively, at least for some loads, manual activation by a user may preempt control of the load's utility consumption by the computing device. Moreover, the system and method may provide for override capability for a load managed by an embodiment.
As shown, the switch 218 and sensor 220 may be packaged together in a unit 226. MLMS sensors or other technology may be utilized in embodiments to precisely monitor sources of consumption.
Switch unit 214 and sensor unit 216 may separately communicate 228 with computing device 230, which incorporates a processor 232 and memory 234. In another embodiment, switch and sensor unit 226 may communicate 229 with computing device 230. In still another embodiment shown in
The set of switches 214, 218, and 222 are included in a wired or wireless network. This network may be connected, as shown in
Memory 234 includes instructions 236 and may include separate criteria 238 to provide direction for controlling utility consumption through sensor 216 and switch 214, for the load at 208, for example. In addition, a connection 240 to a facility network 242 may be provided. Network 242 may be a LAN or a WAN, and may provide access to, for example, productivity or production planning databases for coordination with productivity goals, as will be discussed further below.
Turning now to
As further shown in
The coordination between load activations, and staggering of the onset of utility consumption by loads, as discussed in connection with
In another embodiment, the restriction of utility consumption by the load to a particular time slice occurs only if a high consumption criterion is met. This high consumption criterion may be defined in terms of utility consumption by the entire facility, utility consumption by a region of the facility, or utility consumption by one or more specific clusters of one or more loads.
In another embodiment, the restriction of utility consumption by the load to a particular time slice occurs only if utility consumption is trending upward and its average rate of increase over a specified time period exceeds a predetermined value. As with the high consumption criterion above, this trending criterion may be defined in terms of the rate of utility consumption increase by the entire facility, the rate of utility consumption increase by a region of the facility, or the rate of utility consumption increase by one or more specific clusters of one or more loads.
In another embodiment, utility consumption by a load is restricted if a high utility consumption criterion is met, and allowed otherwise, without regard to partitioning into time slices the availability of utility consumption to different loads.
In another embodiment, utility consumption by a load is restricted if utility consumption is trending upward as discussed above, and allowed otherwise, without regard to partitioning into time slices the availability of utility consumption to different loads.
In still another embodiment, activation of loads is coordinated through a computing device. This may be accomplished, for example, through an algorithm that takes into consideration each load's utility consumption requirement, both as to rate and duration, as well as an assigned priority for each load's activation.
In another embodiment, a protocol to control which loads are permitted to initiate utility consumption may be used. According to the protocol, loads wishing to consume the utility would be allowed to initiate consumption independently. The loads monitor the sensor network to determine if other loads begin utilizing the same utility concurrently. Although the number of loads that may use the utility is not generally fixed, limits may be imposed on the amount (e.g., in amperes or watts) and duration of utility consumption for individual loads, as well as total consumption due to all loads. When simultaneous consumption beyond the imposed limits is detected, a load may cease its own consumption, wait a randomized amount of time and try again later. These limits may be subject to fixed or dynamic priorities. For example, safety (e.g., building lighting) may have priority over production (e.g., weld guns), but production may trump comfort (i.e., HVAC). The protocol may be governed by a central computer (e.g., as in
In yet another embodiment, staggered activation of a set of loads may be accomplished by way of pre-programming the staggered activation of the set of loads. In another embodiment, the pre-programmed staggering may employ an algorithm whose inputs may include production goals and/or data from a production planning database.
As with the high consumption criterion and the trending criterion discussed earlier, each of these embodiments may be practiced with regard to the entire facility, a region of the facility, or one or more specific clusters of one or more loads.
Sometimes, though, standby mode acts to drive utility consumption up. This can occur when the mean time between regular uses of the load exceeds the difference in the peak consumptions with and without the standby capability, divided by the rate of utility consumption during standby. In the embodiment shown in
Referring now to
Referring now to
Conversion technology may comprise fuel cells for reversible interconversion of a fuel to electricity, rectifiers for conversion of alternating current (AC) to direct current (DC), inverters to convert DC to AC, motors and other actuators to convert electrical energy to mechanical energy, generators to carry out the conversion of mechanical energy to electrical energy, and heating and cooling units to convert a utility of one form into heating or chilling capacity.
In the embodiment 800 shown in
A storage/conversion unit at 802 appears as a load to supply 202. A utility intertie or utility interface 804 ensures against backfeeding, in embodiments in which supply 202 is electrical. In
A monitor unit 806 tracks consumption at the utility meter. Data from module 806 is provided to a control unit 808. Control unit 808 provides commands to storage/conversion unit 802 on whether to draw utility consumption units, and thus act as a load on supply 202.
Alternatively, control unit 808 provides commands to storage/conversion unit 802 to convert from stored form and deliver units of utility to utility interface unit 804. Control unit 808 may be configured to record data from module 806 in a database to track historical consumption. Control unit 808 may also be configured to retrieve historical data from the database.
In one embodiment, control unit 808 may command the storage/conversion unit to draw utility if facility consumption satisfies a criterion, e.g., if consumption is lower than a predetermined value, and if storage reserves are below a predetermined level. Control unit 808 may further command the storage/conversion unit to deliver utility if facility consumption satisfies a criterion, such as utility consumption exceeding a predetermined value, or rate of increase of utility consumption exceeding a predetermined value.
As mentioned above,
If at step 1130 utility consumption is not low enough 1146, then in a step 1148 utility consumption is checked to determine whether consumption is high enough to possibly warrant conversion of reserve capacity back to utility. If yes 1150, then at a step 1152 available reserve capacity is checked as to sufficiency. If reserve capacity is sufficient 1154, then in a step 1156 reserve capacity is converted to utility and provided to the utility interface 802. Continual monitoring of utility consumption by the facility is provided for at 1158. If at step 1152 available reserve capacity was not found sufficient, continual monitoring of utility consumption by the facility is provided for at 1160. If at step 1148, utility consumption is not high enough to warrant conversion of reserve capacity to utility, continual monitoring of utility consumption by the facility is provided for at 1162.
It will be apparent to one skilled in the art that testing of utility consumption and available reserve capacity against their respective criteria may take place in any order, one specific order being shown in
As described above, embodiments may take the form of computer-implemented processes and apparatuses for practicing those processes. Embodiments may also be embodied in the form of computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other computer-readable storage medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. Embodiments can also take the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the invention. When implemented on a general-purpose microprocessor, the computer program code segments configure the microprocessor to create specific logic circuits.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.