Patent Publication Number: US-2016248251-A1

Title: Variable feed-out energy management

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 62/120,239, filed on Feb. 24, 2015, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the disclosed subject matter generally relate to the field of distributed energy source management, and more particularly to systems and methods for managing transfer of energy between a variable output allocation and local energy loads. 
     BACKGROUND 
     Electrical grids form interconnected networks that deliver electrical power from suppliers to energy consumers. Traditionally, electrical grid power sources delivered energy from centralized, large-scale electrical generators to vast numbers of final electrical loads at consumer sites. Grid power supply management was designed to support and conform to this largely unidirectional flow of electrical energy. 
     Continued development of energy sources has resulted in changes in methods by which electric grids and energy utilities distribute electrical energy. Namely, technological advances have contributed to an emergence of on-site consumer energy control systems. These consumer energy control systems enable local energy generation systems, such as home-based photovoltaic systems, to supply electrical energy into the external, centralized electrical grid network. Local energy generation systems may comprise energy generators that generate electrical energy from relatively non-exhaustible sources. Such energy generators may include photovoltaic systems and wind turbine systems. 
     The increasing prevalence of decentralized electrical energy generators presents challenges relating to the stability of electrical grid supply. To maintain supply, energy suppliers have utilized consumer incentives to reduce energy intake from distributed sources and increase energy intake from localized sources. These consumer incentives are commonly referred to as feed-in tariffs. 
     SUMMARY 
     Various embodiments for managing energy consumption within an energy management system are disclosed. In one embodiment, the energy management system includes a management controller configured to control activation of a plurality of load devices. The management controller processes a feed-out limit message. The feed-out limit message indicates a power limit associated with a feed-out limit period. In one embodiment, the management controller determines a predicted average surplus power level over the feed-out limit period and modifies an activation schedule of at least one of the plurality of load devices based, at least in part, on the predicted average surplus power level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present embodiments may be better understood by referencing the accompanying drawings. 
         FIG. 1  is a block diagram depicting an architectural overview of a networked electrical energy transfer environment, in accordance with one embodiment; 
         FIG. 2  is a block diagram illustrating features of a controller device, according to some embodiments; 
         FIG. 3  is a diagram depicting a load management messaging protocol in accordance with one embodiment; 
         FIG. 4A  is a flow diagram illustrating processing and communications performed during load management, in accordance with one embodiment; 
         FIG. 4B  depicts a flow diagram showing processing and communications performed during load management, in accordance with one embodiment; 
         FIG. 4C  depicts a flow diagram showing processing and communications performed during load management, in accordance with one embodiment; and 
         FIG. 5  depicts an example computer system for implementing embodiments of the disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     The following description discloses example techniques and structures that embody the subject matter herein. However, it is understood that the described embodiments may be practiced without these specific details. In other instances, well-known instruction instances, protocols, structures and techniques have not been shown in detail in order not to obfuscate the description. 
       FIG. 1  is a block diagram depicting an architectural overview of a networked electrical energy transfer environment, in accordance with one embodiment.  FIG. 1  shows an energy management system (EMS)  100  and an external power grid  136 . The EMS  100  comprises multiple interconnected power generators and load devices. The EMS  100  may be implemented within a home, a business, or other environments. The EMS  100  may enhance energy efficiency of its load devices and subsystems, and reduce energy costs. 
     As shown in  FIG. 1 , the EMS  100  is connected to the external power grid  136 , which may be connected to one or more energy sources, such as electric power plants (not depicted). The EMS  100  may both receive and transmit electrical power from and to the external power grid  136 , with the exchange monitored by a meter  134 . The EMS  100  includes a management controller  102 , which functions as a centralized energy controller for the various energy-related devices associated with the EMS  100 . 
     The solid, dotted, and intermittent dot-dashed lines in  FIG. 1  represent communication and power transfer connections between various devices within the depicted energy transfer environment. The solid lines represent direct current (DC) power transfer. The intermittent dot-dashed lines represent alternating current (AC) power transfer. The dotted lines represent communication channels between devices. These power connections and communication channels may be unidirectional or bi-directional. For example, the devices within the EMS  100  may transmit their respective operational state information to the management controller  102  via the communication channels. The devices may determine whether to update their operational states based, at least in part, on the received data and/or control instructions. 
     The load devices include a heating, ventilation, and air conditioning (HVAC) unit  106  that provides temperature control within an enclosed structure, such as a home. Activation of the HVAC unit  106  is controlled by a thermostat  105 . The thermostat  105  is configured to monitor the operational state of the HVAC unit  106  with respect to air temperature. The thermostat  105  may receive scheduling instructions from the management controller  102 . The scheduling instructions enable scheduling of the HVAC unit  106  to coordinate scheduling with other load devices within the EMS  100 , as will be discussed further below. The load devices further include a water recirculation pump  108  and a battery management unit  110 . 
     The EMS  100  may supplement energy received from the external power grid  136  with power from local power generators. In the depicted embodiment, the EMS  100  is connected to two local power generators: a photovoltaic (PV) panel  120  and a micro combined heating and power (CHP) unit  118 . The PV panel  120  is controlled, in part, by an inverter  130 , which also functions to convert the direct current (DC) power generated by the PV panel  120  into alternating current (AC) power. The inverter  130  may implement maximum power point tracking and/or other techniques to improve utilization of the PV panel  120 . The inverter  130  may report, to the management controller  102 , an instantaneous and/or recorded energy generation rate (e.g., power measured in kW) and other power generation parameters associated with the PV panel  120 . In some embodiments, the inverter  130  receives control instructions from the management controller  102 . 
     The micro CHP unit  118  may utilize fuel from a fuel source (not shown) to generate power while simultaneously generating recoverable heat for a local enclosure. Generating power and recoverable heat may be known as cogeneration. The micro CHP unit  118  may similarly report an instantaneous and/or recorded energy generation rate and other parameters (such as the level of stored heat and/or water temperature) to the management controller  102 . The management controller  102  may change the operational state of the micro CHP unit  118  based on power consumption needs and power output limitations of the EMS  100 . 
     The EMS  100  further includes one or more local energy reserves, such as a battery  122  for storing energy locally. The battery  122  is connected to the battery management unit  110 , which may monitor, charge, and discharge the battery  122 . The battery management unit  110  may report, to the management controller  102 , an amount of charge stored by the battery  122 , an instantaneous charging or discharging rate, and recorded charging and charge levels and rates. 
     Local energy reserves, such as energy reserves store by the battery  122 , allow the EMS  100  to store excess energy that may be either received from the external power grid  136  or generated by local power generators (e.g., the PV panel  120 ). The local energy reserves provided by the battery  122  can provide increased flexibility for coordinating energy consumption over a period of time. Furthermore, local energy reserves can also attenuate spikes in the net energy for be drawn from the external power grid  136  when numerous load devices are simultaneously active. 
     The meter  134  monitors and actuates energy transfer between the external power grid  136  and the EMS  100 . A load center  132  may receive AC power from the external power grid  136  through the meter  134  and may distribute this power to various load devices. The load center  132  may also receive AC power from local energy sources, such as the micro CHP unit  118  and the inverter  130 . In addition, the load center  132  may provide access for manually activating and deactivating loads and subsystems. 
     As further depicted in  FIG. 1 , the management controller  102  is connected to a connectivity hub  104 . In some embodiments, the connectivity hub  104  may be implemented as a router having Wi-Fi capability. The connectivity hub  104  may function to enable the management controller  102  to communicate with the various load devices (e.g., HVAC unit  106 ), energy reserves (e.g., battery  122 ), and power generators (PV panel  120 ). The connectivity hub  104  may further enable the management controller  102  to communicate with external network servers, such as an external grid server  138 . 
     For device connectivity, the loads, power generators, and energy reserves may include control modules to enable communication with the management controller  102 . In the depicted embodiment, power generators, such as micro CHP unit  118  and PV panel  120 , each have such control modules ( 124  and  126  respectively as illustrated) to both receive instructions and send data to the management controller  102  through connectivity hub  104 . Similarly, load devices such as the thermostat  105 , the water recirculation pump  108 , and the battery management unit  110 , each have respective control modules  112 ,  114 , and  116 . The inverter  130  has control module  131  and the meter  134  has control module  133 . The battery  122  has control module  128 . Communication may entail using established protocols for compatibility. These protocols may include Wi-Fi®, Bluetooth®, powerline communication, Zigbee®, Z-Wave, Ethernet and/or other communications protocols. The control modules may be external to or incorporated within their respective devices. 
     To simplify expansion of the EMS  100 , the management controller  102  may support ad-hoc discovery of power generator and load devices. For example, the management controller  102  may periodically (or upon user instruction) send out a request to discover non-configured devices that include system-compliant control modules. 
     In some embodiments, the management controller  102  may communicate with devices within the EMS  100  using the Smart Energy Profile 2.0 (SEP2.0) standard, also known as the Institute of Electrical and Electronics Engineers P2030.5 standard. This communications standard provides an application layer specifically designed to support communications between various smart energy devices within a local area network. The SEP2.0 standard functions independent of the media access control (MAC) and physical layers of end devices (e.g., devices in the EMS  100 ), thereby promoting increased compatibility. 
     Embodiments of the management controller  102  include memory that stores machine-executable instructions that cause the management controller  102  to perform the tasks and functionalities described herein. The management controller  102  may further include and/or communicate with a resource management application (not shown in  FIG. 1 ). The resource management application may include program instructions and data associated with load device power and energy consumption parameters, configuration, and activation schedules. The resource management application will be described in more detail below, in the discussion of  FIG. 2 . 
     The EMS  100  further includes a generator controller  135 , which may be incorporated within or otherwise co-located with the inverter  130 . The generator controller  135  functions to control and adjust the output power level of the PV panel  120 . The generator controller  135  is communicatively coupled via the control module  131  or its own communication interface with the management controller  102 , the meter  134 , the external power grid  136 , and the load devices. 
     In some other embodiments, the management controller  102  is embedded in one of the load devices, such as the thermostat  105 . In some embodiments, the management controller  102  and/or the generator controller  135  is/are embedded in the connectivity hub  104 . In yet other embodiments, the management controller  102  and/or the generator controller  135  and their associated functionality are distributed over multiple devices. Additionally, the management controller  102  and/or the generator controller  135  may have distributed capabilities, such as those facilitated through cloud computing facilities. 
       FIG. 2  is a block diagram illustrating features of a controller device, according to some embodiments. A controller device  200  may be representative of the management controller  102  and/or the generator controller  135  depicted in  FIG. 1 . In  FIG. 2 , the controller device  200  is a “smart” controller, having features extending beyond those associated with other interface-specific computer controllers. Although not shown, the controller device  200  can include user input/output systems, displays, and/or other suitable components. The controller device  200  includes a network interface  202 , which may be a wireless or wireline interface for communicating with an external grid server across a network, such as the Internet. The controller device  200  further includes a processor  204  and memory  210 . The memory  210  and the processor  204  cooperatively function to manage programs and data that enable the controller device  200  to perform various energy management tasks associated with local power generators and load devices. The controller device  200  further includes a communication interface  205 . The communication interface  205  may support one or more of Wi-Fi®, Zigbee®, Bluetooth®, etc. The communication interface  205  includes an interface controller  207  for communicating with various power generation and load devices directly or via a hub (e.g., the connectivity hub  104  in  FIG. 1 ). The communication interface  205  also includes an antenna  206  for generating and maintaining wireless connectivity with other interface-enabled EMS devices. 
     The memory  210  comprises a non-transitory machine-readable storage medium that stores programs and supporting data that control operations of the controller device  200 . In the depicted embodiment, the memory  210  stores an operating system (OS)  230  and includes an application space  212  in which a resource management application  215  is maintained. OS  230  may be a flexible, multi-purpose OS such as that found in smartphones or may be an embedded OS having more limited and specialized functionality. The OS  230  generally comprises code for managing and providing services to hardware and software components within the controller device  200 . Among other code and instructions, the OS  230  may include process management code comprising instructions for interfacing application code with system hardware and software. The OS  230  may also include memory management code for allocating and managing memory for use by application and system-level programs. The OS  230  may further include I/O system management code including device drivers that enable the controller&#39;s hardware to communicate with external systems, such as a user&#39;s smartphone. 
     The resource management application  215  contains management code  225  (machine executable instructions) and associated data including load device power and energy consumption parameters, configuration, and activation schedules. For example, the resource management application  215  may be a user application for coordinating activation and deactivation of load devices, such as in a manner described with reference to  FIGS. 4 and 5 . 
     The resource management application  215  further includes load device entries  216 ,  218 , and  220 , each associated with a respective load device. The depicted load device entries each comprise a load category field (LDTYPE_1 for load device entry  216 , LDTYPE_2 for load device entry  218 , and LDTYPE_3 for load device entry  220 ) concatenated with or otherwise logically associated with a power rating field (RTG_1 for load device entry  216 , RTG_2 for load device entry  218 , and RTG_3 for load device entry  220 ). Each of the load category fields includes data specifying an electrical load category that the controller device  200  may apply during load device scheduling. In one embodiment, the load categories include a Type 1 load for constant power level devices. A constant power level device is one that operates at a relatively constant power level independent of scheduling by the controller device  200 . For example, the water recirculation pump  108  may be in the Type 1 load. The load categories may further include a Type 2 load for devices that operate based on a duty cycle that is independent of management controller scheduling, such as the HVAC unit  106  depicted in  FIG. 1 . The load categories may further include a Type 3 load for variable power devices that operate at an adjustable or otherwise variable power level, such as the battery management unit  110  depicted in  FIG. 1 . 
     The resource management application  215  further comprises (or is logically associated with) generator output records  223  and unscheduled energy consumption records  219 . These records may be stored in any suitable data store, such as a relational database. The generator output records  223  may store energy and/or power output parameters associated with one or more power generators, such as the PV panel  120  and the micro CHP unit  118  depicted in  FIG. 1 . Such parameters may be manufacturer metrics and/or may include historical power/energy output metrics measured and recorded over time within an EMS. The unscheduled energy consumption records  219  may include historical power/energy consumption metrics associated with an EMS. These metrics may indicate a cumulative power and/or energy consumption and/or consumption patterns of all unscheduled electrical loads (e.g., manually activated lights) within the EMS. 
     The resource management application  215  may further comprise (or otherwise be logically associated with) a device activation schedule  227  that includes scheduling information. The scheduling information can include recorded activation schedules for load devices and power generators. The device activation schedule  227  may further include instructions for activating and/or deactivating the load devices and power generators in accordance with the scheduling information. During execution of the management code  225 , the controller device  200  can process the scheduling information in association with information within the load device entries  216 ,  218 , and  220  to determine energy consumption patterns that may be processed in association with a feed-out limit message. The controller device  200  can schedule load devices based on the feed-out limit message, the energy consumption patterns, and real-time power output and energy consumption variations, as described in further detail with reference to  FIG. 4 . It is noted that in this disclosure, “feed-out” refers to power or energy that is generated or produced locally and supplied to an external power grid or some other external energy or power consumer. The term “feed-out” may be used interchangeably with the term “feed-in” as commonly used in the industry. 
     Alternately, or in addition to maintaining the resource management application  215 , the application space  212  may maintain a generator management application  233 . The generator management application  233  may include management code for tracking the activation status of load devices to determine real-time collective power consumption level of load devices. The generator management application  233  may further include code for comparing the collective power consumption level with a power limit specified by a feed-out limit message. In some instances, the controller device  200  is configured as a generator controller, such as generator controller  135 . The generator management application  233  can provide control instructions for adjusting the output power level of a power generator (e.g., a PV panel), based on whether the current collective power consumption level exceeds a specified power limit. The discussion of  FIG. 4  describes this in further detail. 
       FIG. 3  is a diagram depicting a load management messaging protocol in accordance with one embodiment. The entities operably involved in the example load management messaging protocol include a management controller  302 , a meter  304 , one or more load devices  306 , power generators  307 , and an external power grid  308 . The management controller  302  may include hardware and/or software for managing load activation and load activation scheduling within an energy management system. The external power grid  308  provides an external electrical power source to the energy management system that is managed by the management controller  302 . The meter  304  is a device for measuring transfer of electrical energy and a power level transferred between the external power grid  308  and the energy management system. The meter  304  is communicatively and electrically coupled to both the external power grid  308  and the management controller  302 . The load devices  306  are devices that consume electrical power supplied by either or a combination of power generators  307  and/or the external power grid  308 . The load devices  306  may include communication interfaces, such as local wireless interfaces for communicating with the management controller  302 . 
     As shown, the protocol begins with device discovery messages  312  between the management controller  302  and load devices  306 . The management controller  302  exchanges device discovery request and response messages with one or more of the load devices  306  to obtain system information regarding the composition and configuration of load devices. 
     The management controller  302  monitors electrical energy transfer between the energy management system and the external power grid  308  by exchanging power transfer status messages  314  with the meter  304 . While monitoring energy transfer between the energy management system and the external power grid  308 , the management controller  302  receives a feed-out limit message  316  from the external power grid  308 . In one embodiment, the management controller  302  receives the feed-out limit message  316  directly from the external power grid  308 . Alternatively, the management controller  302  may receive the feed-out limit message  316  via the meter  304 . The feed-out limit message  316  specifies a maximum power level (e.g., in kW) that may be fed-out from the energy management system to the external power grid  308 . Alternatively, the feed-out limit message  316  may comprise a message that specifies a maximum energy amount or power level to be fed-out from the energy management system to the external power grid  308  over a specified period. 
     After receiving the feed-out limit message  316 , the management controller  302  may transmit activation schedule messages  319  to one or more of the load devices  306 . The management controller  302  transmits the activation schedule messages  319  to obtain activation schedule and power consumption parameters. In response, the load devices  306  may transmit activation schedule messages  320  containing activation schedule and power consumption parameters. The management controller  302  processes the activation schedule messages  320  to determine power consumption parameters. Alternatively, the management controller  302  may access the load device information via an internal memory access  318 . The information received within the activation schedule messages  320  may include the identity of load devices that are currently scheduled to be activated during a feed-out limit period specified by the feed-out limit message  316 . The activation schedule messages  320  may further specify the portion(s) of the feed-out limit period in which the load devices  306  are scheduled to be activated. The activation schedule messages  320  may further include power/energy consumption parameters associated with each of the currently scheduled load devices. Based on the power limit and the feed-out limit period specified by the feed-out limit message  316 , and the load device schedule and power consumption parameters, the management controller  302  may modify the scheduling of one or more of the load devices over the feed-out limit period. The schedule modification may include modifying the activation periods of load devices currently scheduled to be activated during the feed-out limit period. The schedule modification may also or alternately include scheduling load devices not currently scheduled to be activated during the feed-out limit period. The management controller  302  may then generate and transmit the modified device activation schedule within a modified activation schedule message  321  to the load devices  306 . 
     Based on the modified activation schedule message  321  and the feed-out limit message  316 , the management controller  302  transmits to the power generators  307  a modified feed-out limit message  322  that may specify a limit on the power level to be generated by one of the power generators  307 . The management controller  302  may further exchange net energy transfer messages  324  with the meter  304  to monitor net energy transfer between the energy management system and the external power grid  308 . For example, the management controller  302  may request the net energy transferred between the energy management system and the external power grid  308  from the meter  304 . The net energy transfer messages  324  may include responses from the meter  304  specifying the net energy transferred between the energy management system and the external power grid  308 . The net energy transferred may be an amount of energy transferred over a period of time from the external power grid  308  to the energy management system. The net energy transferred may also or alternately be an amount of energy transferred over a period of time from the energy management system to the external power grid  308 . 
     Using the net energy transfer messages  324 , the management controller  302  can determine energy transfer metrics that enable the management controller  302  to track energy consumption of unscheduled load devices in the energy management system. An unscheduled load device may refer to load device that is not included in activation scheduling (e.g., manually activated lights and electronic devices). As described vis-à-vis  FIG. 4 , the unscheduled energy consumption can be determined by subtracting the scheduled energy consumption from the total energy consumption. The scheduled energy consumption may comprise the current energy consumption of scheduled devices (i.e., devices included in activation scheduling). The current energy consumption of scheduled devices may be determined by identifying which of the scheduled devices are currently activated. The activation schedule message  320  and/or the modified activation schedule message  321  may be accessed to identify which of the scheduled devices are currently activated. 
     The management controller  302  may process the unscheduled energy consumption and generator energy output to generate and send an adjusted activation schedule message  326  to the load devices  306 . The adjusted activation schedule message  326  specifies time intervals over which one or more load devices are scheduled to be activated for all or portions of the feed-out limit period. For example, the specified feed-out limit period may be a period of 8 hours beginning at 10:30 AM to 6:30 AM on January 3. The adjusted activation schedule message  326  may include data and instructions specifying that one or more load devices be activated for one or more time intervals between 10:30 AM and 6:30 AM on January 3. 
       FIG. 4A  is a flow diagram illustrating processing and communications performed during load management, in accordance with one embodiment. At block  404 , a management controller communicates with a meter to monitor the transfer of electrical energy between an energy management system and an external power grid. The management controller can monitor the transfer of electrical energy in real-time which may include monitoring the power level measured by the meter (e.g., as measured by the meter in kilowatts (kW)). Alternately, the management controller may monitor energy transfer directly by monitoring the amount of energy measured by the meter (e.g., as measured by the meter in kilowatt hours (kWh)). Particularly, the management controller may monitor the net energy transferred into or out of the energy management system. The management controller can use the net energy amount to modify activation scheduling of load devices in the energy management system. In some instances, the management controller can use the net energy amount along with a feed-out limit message to modify activation scheduling of load devices within the energy management system. 
     At block  406 , the management controller receives or processes a feed-out limit message while monitoring energy transfer at the meter. In one embodiment, the feed-out limit message may be received at the management controller from an external source, for example, an external power grid. In another embodiment, the feed-out limit message may be installed in the management controller at a manufacturer or distributer of the management controller. In some embodiments, multiple feed-out limit messages may be received or installed and processed by the management controller. If the feed-out limit message is transmitted, the feed-out limit message may be transmitted from an electric grid server system, or some other external source, to the meter and/or to the management controller directly. 
     The feed-out limit message may specify a feed-out limit (e.g., in kW) to be fed-out from the energy management system to the external power grid over a feed-out limit period. The feed-out limit message may also indicate a maximum energy amount (e.g., in kWh) to be fed-out from the energy management system to the external power grid over a feed-out limit period. In one embodiment, the feed-out limit message may indicate that during a certain time period, e.g. 1 PM-3 PM, no energy may be fed out. In another embodiment, the feed-out limit message or some other message, may indicate a value of the energy to be fed-out, e.g. how much the consumer will be paid for the fed-out energy by the power company. In this case, the management controller may make a determination based on the value of the energy, whether to feed-out the energy or use it to power local loads. At block  406 , the management controller may further process the received feed-out limit message to determine the specified feed-out limit and associated feed-out limit period and in some cases may determine a value of the energy to be fed back to the external power grid. 
     The management controller may adjust the power level feed-out to the external power grid based on the feed-out limit message and an activation schedule, which may be modified as described herein. The schedule modification may begin with the management controller determining a predicted average surplus power level over the feed-out limit period. As shown at block  408 , the management controller may estimate an amount of energy to be generated by one or more power generators within the energy management system, during the feed-out limit period. The management controller may estimate the power generators&#39; energy output by accessing power generator activation data, which may be stored in an activation schedule (e.g., see device activation schedule  227  in  FIG. 2 ). The activation schedule specifies which power generator(s) are scheduled to operate during, and for what portion of, the feed-out limit period. The power generator energy output data can include historical power and/or energy output data for the respective power generator devices. The management controller may also estimate the power generator devices&#39; energy output by accessing recorded generator energy output data (e.g., generator output records  223  in  FIG. 2 ). The power generators&#39; energy output may be further estimated based on data such as weather forecasts, historical consumption patterns, and occupancy information. 
     The average surplus power level may be predicted based on the energy generation estimate and on an estimated amount of energy to be consumed over the feed-out limit period. Estimating energy consumption begins at block  410 , where the management controller may access current load device activation schedule(s). At block  412 , the management controller may use the current load device activation schedule(s) to identify which load devices are scheduled for activation at some point during, and for what portion of, the feed-out limit period. The load device activation schedules for each load device may be centrally maintained in memory by the management controller. In some instances, load device activation schedules may be contained in individual records maintained by the load devices. The records may be accessible to the management controller. 
     As shown at block  414 , the management controller determines an estimate of the total scheduled and unscheduled energy consumption of the energy management system during the feed-out limit time period. The total scheduled energy consumption estimate may be computed based, at least in part, on power and/or energy rating data, such as may be obtained from the load device entries  216 ,  218 , and  220  in  FIG. 2 . The total scheduled energy consumption computation may be further based on the load device activation schedule. The load activation schedule which is processed with the power and/or energy rating data to obtain the total scheduled energy consumption over the feed-out limit period. The total scheduled energy consumption may be further based on data such as weather forecasts, historical consumption patterns, and occupancy information. The management controller generates the estimated total scheduled and unscheduled energy consumption by adding the determined scheduled energy consumption with an unscheduled energy consumption value. The unscheduled energy consumption value may be estimated based on historical unscheduled power consumption data stored in unscheduled energy consumption records  219  in  FIG. 2 . 
     As shown at block  416 , the management controller can determine the net feed-out energy capacity over the feed-out limit period. To determine the net feed-out energy capacity, the management controller may compare the estimated amount of energy to be generated (block  408 ) with the estimated total energy consumption (blocks  410 - 414 ). In one embodiment, the net feed-out energy capacity may be determined as the amount of energy by which the energy generation estimate exceeds the estimated total scheduled and unscheduled energy consumption. The management controller may determine a predicted average surplus power level (block  417 ) based on the determined net energy over the feed-out limit time period. 
     At block  432 , the management controller may determine whether the average surplus power level exceeds a feed-out limit by a specified margin. The feed-out limit may be specified in a feed-out limit message, which the management controller received or stored earlier in time. If the average surplus power level does not exceed the feed-out limit by the specified margin, the process may continue at block  460  ( FIG. 4C ), where the management controller (or a generator controller) performs real-time tracking of the power generation and consumption. Also at block  460 , the management controller may also determine a feed-out power level based on the real-time power level generated and the real-time power level consumed. If the real-time tracking reveals that the feed-out power level exceeds the feed-out limit (block  462 ), the management controller (or generator controller) may issue a power reduction instruction to at least one of the power generators (block  464 ). 
     In an embodiment, the specified margin may be related to a value of the energy. In this case, the management controller may determine what the costs associated with the surplus power are and how much the surplus power is worth to the external power grid. In some cases, the external power grid may offer little or no financial incentive to feed the power out to the external grid. When the specified margin is related to the value of the energy, the management controller may determine the cost of energy with and without modifying the activation schedule for the feed-out limit period in order to determine whether it is financially reasonable to modify the activation schedule. The management controller may determine to make modifications to the activation schedule that result in the most financial benefit to the consumer. 
     Returning to block  432  ( FIG. 4B ), if the average surplus power level exceeds the feed-out limit by the specified margin, the management controller determines whether the average surplus power level exceeds a power level threshold associated with an adjustable load type (block  434 ). In some instances, the adjustable load type may be a load that draws electrical power in an adjustable variable manner (i.e., operates at an adjustable or otherwise variable power level). For example, a battery charger is a variable power level device that would be included in this load-type category. If the adjustable load threshold is not exceeded (block  434 ), the management controller determines whether an adjustable load device is available to be scheduled for at least some portion of the feed-out limit period (block  442 ). If an adjustable load device is available, the management controller selects the adjustable load device to be scheduled for at least a portion of the feed-out limit period (block  438 ). From block  438 , the management controller may then return to block  408  to estimate energy to be generated by the power generators. 
     Returning to block  434 , if the average surplus power level exceeds the adjustable load threshold, the management controller begins a scheduling sequence (blocks  436 ,  438 ,  440 ,  442 ). The scheduling sequence may use load device categories to schedule loads by load types. In some embodiments, the management controller uses load types such as may be specified in load device entries  216 ,  218 , and  220  in  FIG. 2 . The scheduling sequence begins at block  436 . At block  436 , the management controller determines whether a Type 1 load device is available to be scheduled during at least a portion of the feed-out limit period. In one embodiment, Type 1 load devices may be associated with devices that operate in a continuous manner, and at a relatively constant power level. For example, a water recirculation pump may be categorized as Type 1. The type information may be in load device records. If a Type 1 load device is available to be scheduled, the management controller schedules it for at least a portion of the feed-out limit period. If a Type 1 load device is not available to be scheduled during the feed-out limit period, the management controller determines whether a Type 2 load device is available to be scheduled during at least a portion of the feed-out limit period (block  440 ). In one embodiment, Type 2 load devices operate based on a duty cycle that is independent of management controller scheduling (i.e., powers off and on during scheduled activation). For example, a thermostat controlled HVAC system may be categorized as a Type 2 load device. If a Type 2 load device is available to be scheduled, the management controller schedules it for at least a portion of the feed-out limit period. If a Type 2 load device is not available to be scheduled during the feed-out limit period, the management controller determines whether an adjustable load device is available to be scheduled during at least a portion of the feed-out limit period (block  442 ). If an adjustable load device is not available to be scheduled during the feed-out limit period, the process continues to step  460 . In some embodiments, more or less than three types of loads may be present and each type of load may be iteratively checked based characteristics of the load type. 
     The management controller may modify schedules in a modular manner that schedules Type 1 load devices before scheduling type 2 load devices. After each additional load device is scheduled (at block  438 ), the predicted average surplus power level (determined at blocks  408 - 417 ) incrementally decreases. After scheduling of Type 1 and Type 2 loads, the management controller schedules adjustable load devices for the feed-out limit period (blocks  442  and  438 ) to consume at least a portion of the remaining surplus power level. In this embodiment, the management controller may schedule loads of known types (e.g., Type 1 and Type 2) prior to scheduling adjustable loads. 
     Returning to block  460  in  FIG. 4C , the management controller may commence or continue real-time tracking of the power generation and consumption. If the real-time tracking indicates a feed-out power level that exceeds the feed-out limit specified by the feed-out limit message (block  462 ), the management controller or generator controller may issue a power reduction instruction to at least one of the generator devices (block  464 ). 
     At blocks  466  the management controller monitors the amount of energy consumed by unscheduled load devices (e.g., personal electronic devices and other manually activated/deactivated devices). At block  468 , the management controller monitors the amount of energy generated by variable power generators, such as a PV panel. The management controller monitors these potentially variable energy metrics over a time interval, ΔT, (block  470 ) to determine whether additional schedule modification is needed before the start of, and/or during, the feed-out limit period. In one embodiment, the management controller may determine the total energy consumption of all currently active/operating, scheduled and unscheduled, load devices over ΔT. The management controller may determine the currently active/operating unscheduled energy consumption by subtracting the energy consumption of all currently active/operating scheduled devices from the total energy consumption. The management controller may track the actual energy output of one or more power generators within the energy management system. In one embodiment, the management controller determines the actual energy output from one or more of the power generators based on measurement data from the meter or from generator-incorporated power/energy output measurement devices. 
     As shown at block  470 , the generator output and unscheduled energy consumption information may be collected over ΔT to determine actual energy generation and unscheduled energy consumption values. The unscheduled energy consumption value may refer to currently active devices that were not scheduled. At block  472 , the management controller compares the actual energy generation and unscheduled energy consumption values with the predictively estimated energy generation and unscheduled energy consumption values processed at blocks  408  and  414  in  FIG. 4A . In response to the actual energy generation and unscheduled energy consumption values diverging from the predictively estimated values by a margin (block  474 ), the average surplus power level is again predictively estimated (blocks  408 - 417 ). This predictive estimation may be based, at least in part, on the determined actual energy generation and unscheduled energy consumption values. The activation schedule is adjusted accordingly (again modified) as shown with the process beginning again at block  432 . If the divergence between the actual and predicted values does not exceed the threshold, energy generation and unscheduled energy consumption tracking continues (block  466 ). 
       FIG. 5  depicts an example computer system for implementing embodiments of the disclosure. In  FIG. 5 , a computer system  500  having a resource management unit  510 . The computer system  500  includes a processor  502 , but may include multiple processors, multiple cores, and/or multiple nodes. The computer system  500  includes memory  504  which may be system memory (e.g., one or more of cache, SRAM, DRAM, zero capacitor RAM, Twin Transistor RAM, eDRAM, EDO RAM, DDR RAM, EEPROM, NRAM, RRAM, SONOS, PRAM, etc.) or any one or more of the above already described possible realizations of non-transitory machine-readable storage media. The computer system  600  also includes a bus  505  (e.g., PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus, etc.), a network interface  506  (e.g., an Ethernet interface, a Frame Relay interface, Synchronous Optical Network interface, wireless interface, etc.), and a storage device(s)  508  (e.g., optical storage, magnetic storage, etc.). Resource management unit  510  embodies functionality to implement features described above with reference to  FIGS. 1-4 . Resource management unit  510  may perform operations that facilitate energy management within an environment in which energy is transferred between an energy management system and an external power grid. Resource management unit  510  may perform system management operations including modifying device activation scheduling based on a received feed-out limit message. Any one of these operations may be partially (or entirely) implemented in hardware and/or on processor  502 . For example, the functionality may be implemented with an application specific integrated circuit, in logic implemented in processor  502 , in a co-processor on a peripheral device or card, etc. Further, realizations may include fewer or additional components not illustrated in  FIG. 5  (e.g., additional network interfaces, peripheral devices, etc.). 
     It should be understood that  FIGS. 1-5  are examples meant to aid in understanding embodiments and should not be used to limit embodiments or limit scope of the claims. Embodiments may perform additional operations, fewer operations, operations in a different order, operations in parallel, and some operations differently. In some embodiments, the management controller can implement the operations of  FIG. 4  individually or in combination with other devices. 
     As will be appreciated by one skilled in the art, aspects of the disclosed subject matter may be embodied as a system, method or computer program product. Accordingly, embodiments of the disclosed subject matter may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or one embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, embodiments of the disclosed subject matter may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. 
     Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the disclosed subject matter is not limited to them.