Abstract:
In one embodiment, a method is used to provide dynamic electrical power management which may minimize the potential for overload conditions and may ensure that system performance limits are maintained. The method may dynamically limit the primary load system power draw in response to the net power draw of all other electrical power users on the aircraft which may ensure that the total power levels remain below critical limits. The method may also provide predictive controls to handle rapid load transients. Additionally, if vital functions are not being met, the method may shed other selected aircraft electrical loads which may ensure that adequate power is provided to the primary load system.

Description:
BACKGROUND 
       [0001]    Aircraft secondary power has traditionally been extracted through pneumatic power (engine bleed air), electrical power (shaft driven generators), and hydraulic power (via shaft driven pumps, augmented by pneumatic driven pumps). Pneumatic power has traditionally been used for functions such as hydraulics power augmentation, Environmental Control Systems (ECS), ice protection, nitrogen generation (fuel inerting), and engine starting. Electrical power has traditionally been used for ECS, cabin services, avionics, galley refrigeration, and others miscellaneous functions. In those traditional architectures, the pneumatic and electrical power have been isolated and managed separately. In either case, the designers recognize that the pneumatic and electrical power sources have limits and that the extraction of power from these sources must be managed to ensure critical limits are not exceeded. 
         [0002]    Traditionally, electrical load management has been accomplished in a mostly discrete (on/off) manner. Most loads are either allowed to draw power or not. For example, load shedding of specific power users in the event of an overload, and sequenced restoration of electrical power users after the overload condition has ceased. In some cases, electrical load management has utilized partial load reduction for some power users. However, these reductions were still discrete steps. 
         [0003]    Pneumatic load management has also used similar techniques such as load management via discrete shedding of associated power users (pneumatic load either being completely off or on) or discrete load reduction (loads being set to pre-determined states that reduce power extraction). However, pneumatic power systems also provide more dynamic, real time load management capabilities. The bleed extraction ports naturally limit the total flow, therefore protecting the engine from excess power extraction under most operating cases (in some cases discrete load management must be employed to stay below engine limits). Additionally, when the bleed source is at or near its extraction limits, a pneumatic power system will naturally share power between users. In this case, as one power user draws more flow, another users flow will naturally droop. These sorts of natural power sharing do not occur in the electrical power realm. 
         [0004]    A new secondary power extraction architecture has been developed for the 787 aircraft. This secondary power extraction architecture does not use pneumatic power (bleed air). In this case, the traditional bleed air users use electric power. An outcome of this architecture is a dramatic increase in the electrical power usage levels and a significant increase in the number of electrical power users to integrate and manage via electrical power load management. Although many of the traditional electrical load management techniques discussed above can still be effectively used in this case, they did not offer analogous functionality and flexibility that the dynamic, real time load management capabilities of pneumatic systems offered. 
         [0005]    A method and/or system for dynamic management of electrical power loads is needed in order to decrease one or more problems, such as the potential for overload conditions, of one or more of the existing systems and/or methods in aircraft, non-aircraft, vehicles, structures, and/or devices. 
       SUMMARY 
       [0006]    In one aspect of the disclosure, a method is disclosed for dynamically managing electrical load. In one step, the total electrical load power consumption is continually measured. In another step, the electrical power to the primary load system is progressively and proportionately reduced whenever the total electrical load power consumption at least one of exceeds and is about to exceed a threshold electrical power limit. 
         [0007]    In another aspect of the disclosure, a method is disclosed for managing predicted electrical power load. In one step, a secondary load system electrical power load is predicted. In another step, electrical power is reduced to a primary load system to avoid exceeding a threshold electrical power limit. 
         [0008]    In another aspect of the disclosure, a method is disclosed for managing electrical power overload. In one step, electrical power is severed to a primary load system after a predetermined time limit after a large secondary load system electrical power load occurred which was not anticipated and which resulted in an electrical power overload. 
         [0009]    These and other features, aspects and advantages of the disclosure will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows a system block diagram which may be used under one embodiment of the disclosure to manage dynamic electrical load; 
           [0011]      FIG. 2  shows a flowchart of one embodiment of a method for managing dynamic electrical load; 
           [0012]      FIG. 3  shows a flowchart of one embodiment of a method for managing predicted electrical power load; 
           [0013]      FIG. 4  shows a flowchart of one embodiment of a method for managing electrical power overload; and 
           [0014]      FIG. 5  shows a graph charting time versus power for one embodiment implementing a method of the disclosure; 
           [0015]      FIG. 6  shows a graph charting time versus power for another embodiment implementing a method of the disclosure; 
           [0016]      FIG. 7  shows a graph charting time versus power for another embodiment implementing a method of the disclosure; 
           [0017]      FIG. 8  shows a graph charting time versus power for another embodiment implementing a method of the disclosure; and 
           [0018]      FIG. 9  shows a graph charting time versus power for another embodiment implementing a method of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The following detailed description is of the best currently contemplated modes of carrying out the disclosure. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the disclosure, since the scope of the disclosure is best defined by the appended claims. 
         [0020]      FIG. 1  shows a system block diagram  10  which may be used under one embodiment of the disclosure to manage dynamic electrical load. The system  10  may include the following: an electrical power generation and distribution system  12 ; a primary load system  14 ; a compartment  16 ; a secondary load system  18 ; an electrical load management control system  20 ; and/or an air conditioning control system  22 . In other embodiments, the system  10  may include varying devices and/or systems. 
         [0021]    The system  10  may be used to manage dynamic electrical load of an aircraft  24 . In other embodiments, the system  10  may be used to manage dynamic electrical loads of non-aircraft vehicles, devices, and/or structures. The electrical power generation and distribution system  12  may include one or more power generating and/or distributing device, such as a generator, a power bus and/or other types of devices, which may generate and distribute electrical power  5  to the primary load system  14  and electrical power  7  to the secondary systems  18 . The primary load system  14  may be driven by a motor, a motor controller, and/or other motor combination. 
         [0022]    In one embodiment, the primary load system  14  may comprise an air-conditioning air compressor which generates conditioned air for the compartment  16 , which may comprise an aircraft cabin. In other embodiments, the primary load system  14  may comprise one or more of a motor (with or without a motor controller) driving a pump (water, hydraulic, fuel, etc.) or mechanical system (conveyor belt, actuator for a control surface, landing gear, door, etc.), a resistive load such as a galley, heating system, or entertainment system, or another type of primary load system. In another embodiment, the secondary load system  18  may include one or more secondary load systems such as non-compressor load systems comprising a nitrogen generation system, a wing ice protection system, a hydraulic demand pump, a compartment service system, an avionics system, a fuel pump system, a galley refrigeration system, a fan system, and/or other type of non-compressor load system. In still other embodiments, the secondary load system  18  may comprises any type of secondary load systems. In one embodiment, the threshold electrical power limit  17  may comprise one or more of a critical threshold of an engine, electrical generator, and/or electrical power system device. 
         [0023]    The electrical load management control system  20  may comprise a computer and/or a control system which monitors and controls continuously in real-time the electrical power generation and distribution system  12  and/or the secondary load systems  18 . The air conditioning control system  22  may comprise a computer and/or a control system which monitors and controls the primary load system  14 , and/or which receives thermal feedback from the compartment  16 . The electrical load management control system  20  and the air conditioning control system  22  may communicate with each other. 
         [0024]    The electrical load management control system may determine the following: total electrical power  11  being used by the system  10 , comprising both the primary load system  14  and the secondary load systems  18 ; total secondary load systems  18  electrical power  13  being used/consumed by the system  10 ; primary load system  14  electrical power  15  being used/consumed by the system  10 ; a threshold electrical power limit  17  of the system  10 ; desired primary load system power  5 ; primary load system speed  3 ; primary load system  14  electrical power available  19  to the system  10 ; a primary load system electrical power reduction amount  27  to avoid exceeding the threshold electrical power limit  17  of the system  10 ; necessary electrical power load shedding  21  of the primary load system  14  and/or the secondary load systems  18  to avoid an overload  31  of the system  10 ; a predicted secondary load system  18  electrical power load  23  and/or predicted primary load system  14  electrical power load  25 ; a primary load system  14  electrical power performance criteria based on vital air conditioning performance limits  29 ; a pre-determined time limit  33  of an overload  31  of the system  10 ; and/or other determinations regarding the electrical load of the system  10 . The primary load system  14  electrical power available  19  to the system  10  may be based on one or more electric power limiting algorithms  41  which are designed to prevent electrical overload  31  of the system  10  by limiting the power available  19  to the primary load system  14  in order to prevent an overload  31  of the system  10 . 
         [0025]      FIG. 2  shows a flowchart of one embodiment of a method  124  for managing dynamic electrical load. The method  124  may be implemented to manage continuously, in real-time, dynamic electrical load in the system  10  of  FIG. 1 , in an aircraft  24 , and/or in a non-aircraft vehicle, structure, or device. Each of the below referenced steps of  FIG. 2  are optional. As shown in  FIG. 2 , in one step  126 , an electrical power generation and distribution system  12  may generate and distribute electrical power  5  to the primary load system  14  and electrical power  7  to the secondary load systems  18 . 
         [0026]    In another step  128 , the primary load system  14  electrical power consumption  15  may be continually measured, the total secondary load system  18  electrical power consumption  13  may be continually measured, and/or the total electrical load power consumption  11  may be continually measured. In one embodiment, the total electrical load power consumption may be determined by summing/totaling both the primary load system  14  electrical power consumption  15  and the total secondary load system  18  electrical power consumption  13 . In another embodiment, the total secondary load system  18  electrical power consumption  13  may be determined by subtracting the primary load system  14  electrical power consumption  15  from the total electrical load power consumption  11 . In still another embodiment, the primary load system  14  electrical power consumption  15  may be determined by subtracting the total secondary load system  18  electrical power consumption  13  from the total electrical load power consumption  11 . 
         [0027]    In one step  130 , a threshold electrical power limit  17  may be determined, which may comprise the total threshold electrical power limit  17  of the primary load system  14  and the secondary load system  18  combined. In one step  132 , the primary load system  14  electrical power available  19  may be calculated by subtracting the secondary load system  18  electrical power consumption  13  from the threshold electrical power limit  17 . In another step  134 , the electrical power  5  to the primary load system  14  may be reduced whenever the total electrical load power consumption  11  exceeds and/or is about to exceed a threshold electrical power limit  17 . 
         [0028]    In one embodiment, step  134  may include predicting a secondary load system  18  electrical power load  23 , which may be large and/or rapid, and reducing the electrical power  5  to the primary load system  14  to avoid exceeding the threshold electrical power limit  17  and/or experiencing an electrical power overload  31 . In another embodiment, step  134  may include, when a large secondary load system  18  electrical power load  13  occurs which was not anticipated and which resulted in an electrical power overload  31 , severing the electrical power  5  to the primary load system  14  after a pre-determined time limit  33 . The electrical power  5  to the primary load system  14  may be restored when the total electrical load power consumption  11  is reduced to and/or below the threshold electrical power limit  17 . 
         [0029]    In another embodiment, step  134  may comprise progressively and proportionately reducing the electrical power  5  to the primary load system  14  as the total electrical load power consumption  11  progressively approaches or increases over the threshold electrical power limit  17 . In still another embodiment, step  134  may comprise reducing the electrical power  5  to the primary load system  14  by a primary load system electrical power reduction amount  27 . The primary load system electrical power reduction amount  27  may be calculated by determining the primary load system  14  electrical power  15  being used, subtracting the threshold electrical power limit  17 , and adding the total secondary load system  18  electrical power  13  consumption. In still another embodiment, step  134  may comprise reducing the primary load system  14  electrical power  15  being used/consumed to the calculated primary load system  14  electrical power available  19 . A rate of change of the primary load system power  5  may vary based on conditions, such as the amount of overload and/or flight phase in an aircraft. The rate of change of the primary load system power  5  may also vary based on conditions, such as the amount of margin from a threshold and/or flight phase. 
         [0030]    In step  136 , after the electrical power  5  to the primary load system  14  is reduced because the total electrical load power consumption  11  exceeded and/or was about to exceed the threshold electrical power limit  17 , one or more electrical power loads  13  of the secondary load electrical systems  18  may be shed if the primary load system  14  electrical power  15  is below the vital air conditioning performance limit  29 . In step  138 , the electrical power  5  to the primary load system  14  may not be reduced if the total electrical load power consumption  11  remains below and/or equal to the threshold electrical power limit  17 . In step  140 , after the electrical power  5  to the primary load system  14  was reduced because the total electrical load power consumption  11  exceeded and/or was about to exceed the threshold electrical power limit  17 , the electrical power  5  to the primary load system  14  may be progressively and/or proportionately increased to the primary load system  14  as the total electrical load power consumption  11  progressively and/or proportionately decreases. 
         [0031]      FIG. 3  shows a flowchart of one embodiment of a method  242  for managing predicted electrical power load  23  and/or  25 . The method  242  may be implemented to manage continuously, in real-time, predicted electrical power load  23  and/or  25  in the system  10  of  FIG. 1 , in an aircraft  24 , and/or in a non-aircraft vehicle, structure, or device. In one step  244 , a secondary load system  18  electrical power load  23  may be predicted. In another step  246 , the electrical power  5  to the primary load system  14  may be reduced to avoid exceeding a threshold electrical power limit  17 . The electrical power  5  to the primary load system  14  may be reduced by an amount of power proportional to an amount of predicted total electric load power consumption  23  and/or  25  above the threshold electrical power limit  17 . The reduction of electrical power  5  to the primary load system  14  may be done progressively and/or proportionately. The electrical power  5  to the primary load system  14  may be suddenly reduced and quickly restored to the primary load system  14  at a lower power level without shutting off the primary load system. 
         [0032]      FIG. 4  shows a flowchart of one embodiment of a method  350  for managing electrical power overload  31 . The method  350  may be implemented to manage continuously, in real-time, electrical power overload  31  in an aircraft  24 , and/or in a non-aircraft vehicle, structure, or device. In one step  352 , electrical power  5  to the primary load system  14  may be severed after a pre-determined time limit  33  after a large secondary load system  18  electrical power load  13  occurred which was not anticipated and which resulted in an electrical power overload  31 . In another step  354 , the electrical power  5  to the primary load system  14  may be restored when a total electrical load power consumption  11  is reduced to and/or below the threshold electrical power limit  17 . Alternatively, the electrical power  5  to the primary load system  14  may be suddenly reduced and quickly restored to the primary load system  14  at a lower power level without shutting off and restoring the primary load system. 
         [0033]      FIG. 5  shows a graph  456  charting time versus power for one embodiment implementing a method of the disclosure. Initially, the primary load system  14  is operating at a stable power  15  level in line with the power level desired  5  by the air conditioning system  22 . At this point, the total electrical power  11  is below the critical threshold  17  for the system  10 . Then, the secondary load systems  18  increases the electrical power  13  they use to the point where the total power draw  11  reaches the critical power system threshold  17 . At that moment, the load management controls  20  send a reduced primary load system power available limit  19  and/or  27  to the primary load system controls  22 . In response, the primary load system controls  22  reduce the primary load system  14  speed and power draw  15  below the desired primary load system power  5  in compliance with the primary load system power available limit  19  and/or  27 . As such, the total power draw  11  does not exceed the critical power system threshold  17 . 
         [0034]      FIG. 6  shows a graph  560  charting time versus power for another embodiment implementing a method of the disclosure.  FIG. 6  is much like  FIG. 5 , except the increase in secondary load system  18  power  13  does not cause the total power  11  to reach the critical power system threshold  17 . As such, the primary load system power  15  is able to remain at the level desired  5  by the air conditioning system  22 . 
         [0035]      FIG. 7  shows a graph  662  charting time versus power for another embodiment implementing a method of the disclosure.  FIG. 7  is much like  FIG. 5  except the load management controls  20  are limiting the primary load system power  15  to a level below that desired  5  by the air conditioning system  22 . However, in this case, the limitation imposed on the primary load system power  15  by the load management controls  20  cause a vital air conditioning performance limit  29  to be exceeded. In most cases, these air conditioning limits  29  are in the form of temperature limits for the aircraft cabin  16 . Thermal transients in the aircraft cabin  16  are relatively slow in nature. As such the timeline is shown broken. At the time the vital air conditioning performance limit  29  is exceeded, the air conditioning controls  20  send shed commands  21  to selected aircraft systems to reduce cabin  16  heat loads and/or to reduce the secondary load system  18  electrical loads  13 . In this example, the secondary load system  18  power  13  reduces sufficiently to allow the primary load system  14  power  15  to again operate at the level desired  5  by the air conditioning system  22 . Vital air conditioning performance  29  is re-established and the critical power system thresholds  17  are not exceeded. 
         [0036]      FIG. 8  shows a graph  760  charting time versus power for another embodiment implementing a method of the disclosure. In this example, a large and rapid secondary load system  18  power transient  13  is anticipated by the load management controls  20 . In this case, the primary load system  14  power  15  is quickly reduced to avoid an electric power system  5  overload  31 . Shortly thereafter, the primary load system  14  power  15  is allowed to again to track the load management primary load system power available signal  19 . 
         [0037]      FIG. 9  shows a graph  870  charting time versus power for another embodiment implementing a method of the disclosure. In this example, an unlikely scenario occurs where there is a large and rapid secondary load system  18  power transient  13  which is not anticipated by the load management controls  20 . In this case, the primary load system  14  power  15  can not reduce fast enough to avoid exceeding the critical power system overload threshold  31 . After the overload  31  has occurred beyond a predetermine time limit  33 , the load management controls  20  sever power  15  and  21  from the air conditioning system primary load system  14  to protect the power system from exceeding threshold power limits. The primary load system  14  operation is later restored, and operation is then in line with the load management primary load system power available limit  19 . 
         [0038]    One or more embodiments of the disclosure may provide improved dynamic electrical power management in order to reduce the potential for overload conditions of one or more of the prior art power management systems and/or methods. 
         [0039]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims.