Abstract:
The present subject matter relates to energy management. Home energy management (HEM) devices are directed from a central control system to modify energy usage among appliances/loads within individual homes to meet energy source demand limitations. The HEM devices may work in cooperation with a group of such devices as a unit to negotiate with the central control system and then individually to control energy usage for their separately controlled home appliances/loads to meet group negotiated aggregate energy usage modification, for example, usage reductions so as to minimized peak usage demands on the energy source.

Description:
FIELD OF THE INVENTION 
       [0001]    This disclosure relates generally to energy management systems for homes. More particularly, the disclosure relates to operation of home energy management systems in response to demand response signals. 
       BACKGROUND OF THE INVENTION 
       [0002]    Certain utility companies are experiencing a shortage of electrical generating capacity due to increasing customer demand for electricity. In particular, such utility companies may be unable to meet their customers&#39; demand for electricity during peak demand hours. Increasing electrical generating capacity to meet the shortfall can be difficult due to increasing fuel prices. As a result, utility companies can be forced to buy electricity to meet their customers&#39; demands. If peak demand hours can be reduced, then utility companies and their customers can realize a potential cost savings, and the peak load that the utility companies have to accommodate can also be lessened. 
         [0003]    Certain energy management systems include features for deactivating power consuming devices during the on-peak hours. Such energy management systems can determine when variable electricity-pricing schemes go into effect via schedules published by utility companies and inputted by customers or via signals sent by utility companies, e.g., over a wireless network or through a phone network, directly to the energy management systems. However, inputting schedules manually can be tedious and time consuming. Similarly, energy management systems relying upon utility company input to function properly can function improperly if the utility company fails to deliver the schedules as expected. 
         [0004]    Alternative energy management plans provide systems and methods with time of use (TOU) and/or demand response management systems (DRMS) energy programs. The present disclosure finds particular application to utility systems and appliances configured to manage energy loads to consumers through a communicating consumer control device, such as a home energy manager (HEM), programmable communicating thermostat (PCT), appliance controller, or the like. 
         [0005]    There is a need to provide a system that can automatically operate power consuming devices in order to reduce consumer&#39;s electric bills and also to reduce the load on generating plants during peak hours. Active and real time communication of energy costs of appliances to the consumer may enable informed choices of operating the power consuming functions of the appliance but in many instances consumers may not be present to make necessary usage adjustments or may simply ignore provided information. 
         [0006]    In view of these and other issues, there is a need to provide an improved system that can enable automatic control of power consuming devices during a DRMS event, and thus, provide opportunity for utility companies to better meet the needs of their customers. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0007]    Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention. 
         [0008]    The present subject matter relates to energy management systems. In accordance with some embodiments, such systems comprise a central control system including a demand management system and a plurality of home energy management systems in communication with the central control system. In such systems each of the plurality of home energy management systems is configured for communications with at least one home appliance. In accordance with the present subject matter, the demand management system is configured to transmit demand response signals to each of the plurality of home energy management systems where such signals include instructions to modify overall system usage demand, and wherein each of the plurality of home energy management systems is configured to instruct the at least one home appliance to modify its energy consumption. 
         [0009]    The present subject matter also relates to a method for managing energy usage. In accordance with such method, the overall energy demand in at least a portion of a utility system is monitored from a central control location and demand modification signals are transmitted to a plurality of home energy management systems that then transmit the demand modification signals to at least one home appliance instructing such appliance to modify its energy consumption. 
         [0010]    The present subject matter further relates to a power distribution and control system. In accordance with such system there is provided a central control system, a source of power, a plurality of power consumption locations having at least one power consuming device and an energy management device at each such location, and an advanced metering infrastructure configured to provide communications between the central control system and each the energy management devices. According to such system the central control system is configured to monitor power flow from the source of power to the plurality of power consumption locations and to direct said energy management device located at each of said plurality of power consumption locations to modify the energy usage of at least one power consuming device located at each of the plurality of power consumption locations. 
         [0011]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0013]      FIG. 1  provides an overview of a Demand Response Managements System (DRMS) in accordance with an exemplary embodiment of the present subject matter; 
           [0014]      FIG. 2  illustrates exemplary sequences of Low-Frequency Pulse Width Modulation (PWM) Appliance Response signals produced in response to DRMS signals in accordance with the present subject matter; and 
           [0015]      FIG. 3  illustrates exemplary sequences of Home Pulse Width Modulation (PWM) responses produced in response to DRMS signals in accordance with the present subject matter. 
       
    
    
       [0016]    Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features or elements. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    As discussed in the Summary of the Subject Matter section, the present subject matter is particularly concerned with home energy management systems and methodologies for responding to Demand Response Management requests. 
         [0018]    Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0019]    With initial reference to  FIG. 1 , there is provided an overview of a Demand Response Managements System (DRMS)  100  in accordance with an exemplary embodiment of the present subject matter. In accordance with exemplary embodiments of the present subject matter, Demand Response Managements System (DRMS)  100  includes a Central Command and Control system  110  that, from time to time may send, by way of a Demand Response Server  112 , requests to modify overall system usage demand. Such request are sent from Demand Response Server  112  as system level signals by way of Demand Response Server  112  to the Advanced Metering Infrastructure (AMI)  120  and then to Home Energy Management (HEM) systems  150 ,  152 ,  154  located in association with individual homes representatively illustrated as houses  130 ,  132 ,  134  (House #1, House #2, House #3). 
         [0020]    Those of ordinary skill in the art will appreciate that AMI  120  may correspond to a vast number of devices including transmission lines over which power and possibly communications signals may flow to a large number of individual homes and other facilities or locations. AMI  120  may also include various communications related features including wireless communications or power line communications systems that may be employed to exchange information between individual home or other locations and a central facility relating to consumption and control of such utilities all in accordance with well-known and commonly used AMI arrangements as are fully understood by those of ordinary skill in the art. Such communications systems may also be used in conjunction with the present subject matter to transmit demand request signals from Demand Response Server  112  to individual home energy management systems. 
         [0021]    It should also be appreciated that while the present disclosure is particularly directed to home energy management, such may also be applied to energy management for other facilities including without limitation, commercial and public facilities whose energy demand may also be controlled based on the technology of the present subject matter. Thus in the context of the present disclosure, the use of the terms “home” or “house” is fully intended to include other structures whether used as a residential facility or for some other purpose as long as such facility contains or has associated therewith, energy consuming appliances whose energy consumption may be controlled in accordance with the present subject matter. 
         [0022]    With continued reference to  FIG. 1 , there are representatively illustrated three houses  130 ,  132 ,  134  each of which is supplied with electrical power from a utility and includes associated therewith systems providing bidirectional communications with Central Command and Control  110  by way of AMI  120 . In an exemplary arrangement, homes  130 ,  132 ,  134  are each provided with an electric utility meter  140 ,  142 ,  144  containing metrology components as well as communication components that operate to monitor and report energy consumption information to Central Command and Control  110 . Each home  130 ,  132 ,  134  is also provided with a Home Energy Management (HEM) system  150 ,  152 ,  154  configured to receive instructions from Central Command and Control  110 , or, more specifically, from Demand Response Server  112 . Such HEM systems  150 ,  152 ,  154  may then provide instructions to individual appliances associated with the individual homes  130 ,  132 ,  134 . In an alternative configuration, HEM systems may be incorporated directly in electric utility meters  140 ,  142 ,  144  or, as illustrated, may correspond to stand alone units. Further it should be appreciated that while HEM systems  150 ,  152 ,  154  are illustrated as connected to various home appliances including representatively, dryers  160 ,  162 ,  164 , refrigerators  170 ,  172 ,  174 , and HVAC systems  180 ,  182 ,  184 , such connections may correspond to either wired or wireless connections over which control signals may be uni-directionally or bi-directionally transmitted. 
         [0023]    In accordance with the present subject matter, each home appliance  160 ,  162 ,  164 ,  170 ,  172 ,  174 ,  180 ,  182 ,  184  operates using synchronized low frequency Pulse Width Modulation (PWM) wherein Demand Response Server (DRS)  112  directly controls the maximum duty cycle (dcMax) using a single global command transmitted to all the HEM systems  150 ,  152 ,  154 , that, in turn, control the dcMax of each appliance (device) in their respective homes  130 ,  132 ,  134 . HEMs  150 ,  152 ,  154  are configured to communicate directly with DRS  112  by way of a two-way link through AMI  120 . In this manner the DRS through individual HEMs is able to control the aggregated average operating power level at which each home appliance needs to operate to achieve a desire goal 
         [0024]    In accordance with the present subject matter, when it is determined that a reduction in demand is necessary DRS  112  of the Demand Response Management System within the Central Command and Control system  110  will negotiate a kilowatt hour (kWh) reduction (or other desired demand, e.g., percentage reduction) over a fixed time period with each HEM  130 ,  132 ,  134  through a bid process. In accordance with such bid process, DRS  112  solicits consumption reduction bids and each HEM then estimates possible consumption reductions and makes a bid. DRS  112  may then accept bids or revise its solicitations to a lower reduction level, for example, if bids are not accepted. When bids are accepted, the individual HEMs  130 ,  132 ,  134  then controls the maximum duty cycle (dcMax) of each appliance in its respective home  130 ,  132 ,  134 . 
         [0025]    In accordance with one aspect of the present subject matter HEMs  150 ,  152 ,  154  are aware of the various products/appliances/loads that are on line and are able to monitor the overall home load via the AMI or alternatively through monitoring of their associated individual home utility meter. With this information, the HEMs may be configured to control their various respective appliances in several ways. In a first aspect, certain of the appliances may themselves contain operating software (firmware) that encompasses duty cycle control such that the HEM may direct such appliance to operate using a particular duty cycle based on the desired (accepted bid) reduction. The appliance itself can then operate under the specified criteria by lowering the load produced by the appliance using, for example, a randomized duty cycle method that may be incorporated into the appliance controller. 
         [0026]    In some embodiments of the present subject matter, the duty cycle signal sent to the various appliances (loads) may correspond to a discreet level based on a standardized set of levels or, also possibly, on a continuous level. Other home appliances may not have such software included in their operating systems. In those instances the responsible HEM will generate a randomized duty cycle control signal and transmit such control signal to those appliances (loads), thus allowing them to respond in a manner similar to the appliances (loads) containing the embedded algorithm in their controllers. 
         [0027]    In some other embodiments of the present subject matter, appliance may be installed in certain homes that include communications controllers including “sleep time” functionality. That is, such appliances may be in a sleep mode until the product (appliance) is activated. When such products are activated then the control signals for dcMax reduction will be sent either on an interval basis or a rolling “look ahead” basis containing estimated signals for the next several periods. 
         [0028]    In accordance with a further aspect of the present subject matter individual HEMs  150 ,  152 ,  154  may employ a closed loop control approach to monitor their respective homes. According to such approach, the HEMs may be configured to adjust signals sent to individual appliances (loads) with the objective of meeting the overall demand reduction requested so that the entire home is managed as a single entity. 
         [0029]    In a further aspect of the present subject matter, the DRMS may be configured to monitor the total load on various sub groups of load centers, that is, on a sub group of homes and adjust the signals sent to each sub group to adjust demand reduction requested for each sub group based on their ability to provide requested aggregate load reduction. In accordance with aspects of this portion of the present subject matter, HEMs  150 ,  152 ,  154  may be configured to form a network to communicate among each other and with the DRS  112 . In this manner the HEMs form a Super-Organism Negotiation and Decision (SOND) group, that is, a sub group of HEMs among the large number of such devices associated with the AMI, wherein the DRS may negotiate a kilowatt hour (or other desired demand, e.g., percentage) reduction (or other adjustment/modification) over a fixed time period with the SOND. The HEMs in the SOND then decide (negotiate) among themselves how best to meet a negotiated aggregate level for the SOND. 
         [0030]    With present reference to  FIGS. 2 and 3  there is illustrated respectively exemplary appliance and home PWM operations in accordance with the present subject matter, With respect to  FIG. 2 , there is illustrated an exemplary sequence of controlled start of PWM for a number of individual appliances  202 ,  204 ,  206  associated with an individual home. As shown, the PWM aggregated energy usage, per present disclosure, is controlled to a generally uniform level.  FIG. 2  also illustrates that the calculation of the start of the PWM, i.e., the periodic percentage adjustment of duty cycle to maintain the desired aggregate level of energy usage may also be periodically recalculated. In an exemplary configuration, such recalculations may be performed on an every several minutes basis. While  FIG. 2  is intended to initially illustrate operations with respect to appliances in an individual home, per previous discussion, regarding the SOND configuration,  FIG. 2  may equally be indicative of HEM operation with respect to plural homes. 
         [0031]    For example, as further illustrated in  FIG. 3 , the aggregated load reductions of individual homes forming a sub group of homes by virtue of a formed SOND may be controlled so that not only the individual homes overall (collectively) but also the appliances within each home are controlled to maintain a SOND negotiated energy usage level. For example, as illustrated in  FIG. 3 , house #1 may begin HEM controlled energy usage and then, after a controlled period of time, turn off a dryer for a predetermined time period, followed by controlled interruptions of the operation of HVAC systems and home refrigerators. In exemplary embodiments of the present subject matter such “off” periods may be set to 10 minutes. Alternative times, of course, may be set as well as differing times based on the particular appliances to be controlled. 
         [0032]    With further reference to  FIG. 3 , it will be appreciated that in accordance with the present disclosure, the other houses (house #2 and house #3) that are part of the SOND similarly control, via their respective HEM, their appliances to be cycled off for predetermined times but do so in concert with the HEM controlling house #1 so that not all of the controlled appliances in all of the homes of the sub group that formed the SOND are on at the same time. In this manner the SOND negotiated reduction for the sub group may be effected. 
         [0033]    The present subject matter provides several benefits including the ability of the system operator to control the aggregate residential load and reshape the load curve. The use of these control techniques will allow mitigation of peak loads, control of transient loads at the end of the period and distribution of deferred loads in the post peak period. 
         [0034]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.