Method and system for adaptive power management

In a non-limiting, exemplary embodiment, electrical power is adaptively managed. A profile of predetermined threshold levels of electrical loading is developed for phases of an operation. A profile of electrical loading is developed for the phases of the operation such that electrical loading is substantially a same predetermined margin below the predetermined threshold levels during the phases of the operation. During the phases of the operation, operational data indicative of an electrical power generation system's actual ability to support electrical loading and/or actual electrical loading is received. The profile of the predetermined threshold levels and/or the profile of electrical loading is adjusted responsive to the operational data such that electrical loading is maintained substantially the same predetermined margin below the predetermined threshold levels during the phases of the operation.

BACKGROUND

Electrical power systems generate and distribute electrical power onboard vehicles, such as aircraft and maritime vessels, that are involved in operations, such as flights and voyages, cruises, or patrols. Typically, electrical power generators are rotated by a prime mover that also provides propulsion power for the vehicle. For example, onboard an aircraft an electrical generator is rotated by the aircraft's engine.

Thus, a finite amount of energy is available onboard a vehicle for an operation's propulsion and electrical power requirements. That is, the more energy that is converted into electrical power, the less energy is available for propulsion.

However, current aircraft designs emphasize use of more electrical power onboard an airplane and less use of engine bleed air in order to raise the overall efficiency of an aircraft engine. For example, an electrically powered direct drive starter may be used for start up and electrical power may be used instead of bleed air for an environmental control system onboard an aircraft. In such an arrangement, total electrical loading onboard an aircraft could be raised from around 100 kilowatt (KW) to around 1 megawatt (MW).

With such significant amounts of electrical power being generated and used onboard aircraft, it would be desirable to make the most efficient use of electrical power. However, current load management techniques are designed to protect electrical generators from overloads rather than optimizing electrical power management.

For example, in a typical load management technique, a proportional integral differential (PID) controller selects a threshold and monitors electrical loading. When the PID controller senses that electrical loading may exceed the threshold, the PID controller begins shutting down loads. Currently, loads can be prioritized, such as essential or non-essential loads. However, no operational planning information is used to optimize electrical power generation and electrical load information is not used to adapt electrical power to electrical loads.

The foregoing examples of related art and limitations associated therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.

SUMMARY

The following embodiments and aspects thereof are described and illustrated in conjunction with systems and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the problems described above in the Background have been reduced or eliminated, while other embodiments are directed to other improvements.

In a non-limiting, exemplary embodiment, electrical power is adaptively managed. A profile of predetermined threshold levels of electrical loading is developed for phases of an operation. A profile of electrical loading is developed for the phases of the operation such that electrical loading is substantially a same predetermined margin below the predetermined threshold levels during the phases of the operation. During the phases of the operation, operational data indicative of an electrical power generation system's actual ability to support electrical loading and/or actual electrical loading is received. The profile of the predetermined threshold levels and/or the profile of electrical loading is adjusted responsive to the operational data such that electrical loading is maintained substantially the same predetermined margin below the predetermined threshold levels during the phases of the operation. Thus, planning data as well as operational data may be used to optimize capability of an electrical power generating system. The electrical power generating system may be adapted to the load, and overall electrical loading may be reduced during each phase of the operation.

According to an aspect, the profile of the predetermined threshold levels and the profile of electrical loading may be compared during the phases of the operation. In such a case, the profile of the predetermined threshold levels and/or the profile of electrical loading may be adjusted in response to the comparison such that electrical loading is maintained substantially at the same predetermined margin below the predetermined threshold levels during the phases of the operation.

According to another aspect, in developing the profile of predetermined threshold levels an initial threshold level above which electrical load is not to be added to an electrical power generation system may be developed. An analysis is made regarding when in the operation the initial threshold level will be reached. Threshold levels below the initial-threshold level are established when the initial threshold level will not be reached, and threshold levels above the initial threshold level are established when the initial threshold level will be reached.

According to a further aspect, in developing the profile of electrical loading each of the plurality of phases of the operation may be divided into time periods. Electrical loads for a phase of the operation are sequenced among the time periods for the phase of the operation such that electrical loading is substantially equalized for all of the time periods of the phase operation. In sequencing the electrical loads, an electrical load may be scheduled to operate at its maximum electrical loading level in one of the time periods of a phase of the operation, and another electrical load is scheduled to operate at its maximum electrical loading level in another of the time periods of the phase of the operation.

In addition to the exemplary embodiments and aspects described above, further embodiments and aspects will become apparent by reference to the drawings and by study of the following detailed description.

DETAILED DESCRIPTION

By way of overview and referring toFIG. 1, in a non-limiting, exemplary embodiment electrical power is adaptively managed. In an exemplary method10, at a block14a profile of predetermined threshold levels of electrical loading is developed for phases of an operation. At a block46a profile of electrical loading is developed for the phases of the operation such that electrical loading is substantially a same predetermined margin below the predetermined threshold levels during the phases of the operation. During the phases of the operation, at a block70operational data indicative of an electrical power generation system's actual ability to support electrical loading and/or actual electrical loading is received. At a block60the profile of the predetermined threshold levels and/or the profile of electrical loading is adjusted responsive to the operational data such that electrical loading is maintained substantially the same predetermined margin below the predetermined threshold levels during the phases of the operation. Thus, planning data as well as operational data may be used to optimize capability of an electrical power generating system. The electrical power generating system may be adapted to the load, and overall electrical loading may be reduced during each phase of the operation. Details of exemplary embodiments will now be set forth below.

The method10starts at a block12and proceeds to a block14at which a profile of predetermined threshold levels of electrical loading is developed for phases of an operation. Referring additionally toFIG. 2, in an exemplary embodiment, the operation is a flight of an aircraft16. However, in other embodiments the operation may be other operations of other vehicles, such as without limitation voyages, cruises, or patrols of maritime vessels such as ships or submarines. The flight of the aircraft16includes several phases, such as a gate phase18, a start phase20, and a taxi-from-gate phase22, during which the aircraft16is on the ground and is not yet airborne. The flight of the aircraft16also includes airborne phases such as a climb phase24during which the aircraft16takes off and climbs to cruising altitude, a cruise phase26during which the aircraft16cruises at altitude, and a descent phase28during which the aircraft16descends from cruising altitude and lands. The flight of the aircraft16also includes a taxi-to-gate phase30after the aircraft16lands.

At the block14, a profile32of predetermined threshold levels of electrical loading is developed for the phases18,20,22,24,26,28,30, and32. In an exemplary embodiment and referring additionally toFIG. 3, at a block34a profile is developed of initial predetermined thresholds of electrical loading above which electrical load is not to be added to an electrical power generation system. The profile of initial threshold levels may be made based upon historical thresholds established for use with PID or other types of load management systems during the phases18,20,22,24,26,28,30, and32. The initial threshold levels may additionally be based on the limits of the protective functions in the generating system, from operational information derived from historical correlation of the load data from previous flights with the flight profile from the Flight Management System, and the actual real-time capability of the engine to produce electrical power based on operational data from the Electronic Engine Control (e.g. Flight Phase Engine Power Capability—M “the required power margin”.)

At a block36electrical loading during the phases18,20,22,24,26,28,30, and32is predicted using planning or predictive information from a flight plan (such as may be loaded into a flight computer like a flight management system or the like). The analysis at the block36may be made based on a correlation made at a block38of typical electrical loading with events in the flight plan that are planned to occur during the phases18,20,22,24,26,28,30, and32. The prediction of electrical loading at the block36may also include an analysis of historical load data, if desired, at an optional block40.

At a block42a determination is made when predicted electrical loading for the phases18,20,22,24,26,28,30, and32will reach the initial threshold levels. To that end, the predicted electrical loading from the block36is compared with the initial thresholds from the block34. At a block44the initial thresholds are re-programmed for various phases of the flight based on predicted loading reaching the initial thresholds. For example, the re-programmed thresholds may be lowered slightly from the initial thresholds during the descent phase28and raised slightly from the initial thresholds during the cruise phase26. The re-programmed thresholds might also be lowered from the initial thresholds during transitions from one flight phase to another such as “top of climb” or “top of descent” or other times when the engine might be more susceptible to transient changes in electrical load. This re-programming of the initial thresholds provides the threshold profile32for the entire flight. This re-programmed profile is more optimum than the initial profile because the margin between the engine's capability to generate electrical power and the load is greater for more of the flight phases.

Referring now toFIGS. 1,2, and4, at the block46a profile48of electrical loading is developed for the phases18,20,22,24,26,28,30, and32such that electrical loading throughout the profile48is substantially a same margin M below the threshold levels throughout the profile32during the phases18,20,22,24,26,28,30, and32. At a block50the electrical loads for the phases18,20,22,24,26,28,30, and32that were predicted at the block36(FIG. 3) are retrieved.

At a block52the predicted electrical loads are subdivided into controllable time increments. Referring additionally toFIG. 5Aand given by way of non-limiting example, each of the phases18,20,22,24,26,28,30, and32is subdivided into three time increments. However, any number of time increments may be selected as desired for a particular application. The more time increments that are selected, the greater the granularity can be achieved in subsequent re-sequencing of the loads. The greater granularity in re-sequencing is to be balanced with greater processing costs.

When the phases18,20,22,24,26,28,30, and32are initially subdivided into controllable time increments at the block52, the predicted electrical loading has not yet been optimized to reduce overall loading levels. Thus, predicted electrical loading can range from less than 300 KW during the last time increment of the taxi-to-gate phase30to a maximum loading of around 500 KW during the first time increment of the climb phase24. This initial predicted loading presents a peak-to-peak load swing of greater than 200 KW. Except for the start phase20(which is dominated by starter loading and is, therefore, substantially equalized), loading during the phases18,22,24,26,28,30, and32is not yet equalized or minimized.

At a block54predicted electrical loads for a phase are re-sequenced among the time increments for the phase such that electrical loading is substantially equalized for all of the time periods of the phase. The re-sequencing of the loads at the block54is performed for all of the phases18,20,22,24,26,28,30, and32.

Referring now toFIGS. 1,2,4, and5B, predicted electrical loads for each of the phases18,20,22,24,26,28,30, and32have been re-sequenced among the time increments into which each of the phases18,20,22,24,26,28,30, and32have been subdivided. Any of several exemplary load sequencing schemes may be used. In general, electrical loads are controlled so maximum loads do not arbitrarily coincide.

Several load sequencing techniques will be given by way of non-limiting example. For example, electrical loads in an environmental control system (ECS) can be controlled such that maximum loading does not occur in a same time increment when other loads are at a maximum. For example, ECS loads (such as heaters, compressors, fans, and the like) can be cycled on for short time periods and off for short time periods instead of remaining on for long time periods and off for long time periods. Light intensity can be optimized within an ECS to prevent needlessly maximizing light intensity. ECS mode control can also be optimized between standby and charging modes. Similarly, de-icing loads may be cycled on and off instead of remaining continuously on. As a further example, galley loads (such as coffee pots, ovens, refrigeration compressors, and the like) need not all be on at the same time and instead can be scheduled to be on at different times. As another example, starting of motors, such as fan motors (part of the ECS) and fuel pump motors, can be sequenced such that motor starting current surges do not occur at the same time.

Further, during engine starting it may be desirable to schedule no loads other than those associated with engine startup. This approach may be desirable in cases where starting an engine can take around 450 KW of electrical power that is provided by either shore power, an auxiliary power unit (APU), or battery power. Once an engine has been started, then loads may be supplied by the onboard generator associated with the started engine. Given by way of non-limiting example, an engine electronic control system can supply an engine speed signal that indicates a minimum engine speed above which a generator can assume load.

As a result of re-sequencing loads as discussed above, loads in the time increments in each of the phases18,20,22,26,28,30, and32have been substantially equalized (with the load in the first time increment of the climb phase24being higher than loads in the other time increments of the climb phase24). Moreover, the re-sequenced electrical loading ranges from a minimum loading of around 325 KW during all of the time increments of the taxi-to-gate phase30to a maximum loading of around 425 KW during the first time increment of the climb phase24. The re-sequenced loading thus presents a peak-to-peak load swing of only around 100 KW. Thus, the re-sequenced loading has a lower peak load and reduced peak-to-peak loading from the predicted loading that was not yet re-sequenced.

Referring back toFIGS. 1 and 2, after the loads have been re-sequenced at the block54(FIG. 4) the load profile48is compared to the threshold32at a block56. A determination is made at a decision block58whether the difference between the load profile48and the threshold profile32is less than the margin M. When the difference between the load profile48and the threshold profile32is less than the margin M, at a block60the load profile48and/or the threshold profile32is updated to maintain the margin M between the load profile48and the threshold profile32.

If the load profile48has been adjusted at the block60(as determined at a decision block62), then at a block64loads are adjusted accordingly during operations to implement changes to the load profile48. When operations are complete (as determined at a decision block66), the method10stops at a block68. When operations are not complete, processing returns to the block56.

When the difference between the load profile48and the threshold profile32is not less than the margin M, the method10proceeds from the decision block58to a block70at which operational data is received. The operational data can include real-time data, plotted as an exemplary non-limiting profile72, regarding an electrical power system's capacity to generate electrical power. Given by way of non-limiting example, real-time data regarding electrical power system's capacity to generate electrical power may be provided by an electronic engine control system.

At a block74the electrical power system's capacity to generate electrical power, represented by the profile72, is compared to the threshold profile32. At a decision block74a determination is made whether the electrical power system's capacity to generate electrical power is less than the threshold level. If so, then processing continues to the block60, at which the threshold profile32and/or the load profile48may be updated as desired. If not, then processing continues to the decision block66.

The operational data can also include real-time load data provided from load controllers such as motor controllers or solid state power controllers. Large systems, such as without limitation an environmental control system, can also provide its own load data via load centers.

At a block78, real-time load data is compared to the load profile48. At a decision block80a determination is made whether actual load (represented by the real-time data) is greater than the load profile48. If so, then processing continues to the block60, at which the threshold profile32and/or the load profile48may be updated as desired. If not, then processing continues to the decision block66. Processing of the blocks74and78may occur in any order as desired. The block74may be performed before the block78, or the block78may be performed before the block74, or the blocks74and78may be performed simultaneously, as desired.

Referring now toFIG. 6, an exemplary power and load management system100operates within an exemplary host environment102to adaptively manage electrical power within the host environment102. The system100includes a suitable computer processor (or processors) that can execute instructions to perform analyses associated with the method10(FIG. 1) and that can generate control signals (to control loads and generators) associated with the method10(FIG. 1). Computer processors are known in the art, and therefore a discussion of their construction and operation is not necessary. The system100also includes suitable input interfaces for receiving planned or predictive data and for receiving real-time operational data and output interfaces for providing control signals.

The host environment102suitably is an electrical power generation and distribution system and associated loads onboard a vehicle, such as an aircraft. However, the host environment102can be an electrical power generation and distribution system and associated loads onboard a maritime vessel, such as a ship or a submarine, that has similar operational planning data and real-time operational data as an aircraft.

A flight management system (FMS) provides data to the system100. A guidance buffer resides in storage106that can be accessed by the FMS104. The guidance buffer includes target thrust settings for driving autothrottles. These settings can be correlated to predicted electrical power generation capacity for an electrical generator that is driven by an aircraft engine (that is in turn controlled by the thrust settings of the autothrottles).

A flight plan also resides in storage106. The flight plan provides a profile of several parameters for all of the phases18,20,22,24,26,28,30, and32(FIG. 2). The parameters include altitude, heading, thrust settings, predicted top of climb, predicted top of descent, and step climbs that are correlated against phase in the flight and elapsed time in the flight. Each of these flight phases or segments has detailed time information associated with it. This detailed flight information can then be correlated with the associated airplane electrical loads during that phase of flight.

The FMS104also provides real-time flight status to the system100. The FMS104provides real-time data regarding where the aircraft16(FIG. 2) is relative to the flight plan.

An electronic engine control system108controls engines110and provides real-time operational data to the system100regarding operation of the engines100and any associated limitations on power extraction. Thus, the electronic engine control system108provides real-time data regarding excess load-carrying capability of the engines110. To that end, the electronic engine control system108provides real-time operational data regarding capacity of the electrical power generating system to generate electrical power and accept loading.

The system100receives real-time load data. Loads112(that may be individual loads or groups of loads) are controlled by load controllers114, such as solid state power controllers. Real-time data regarding which of the loads112are operating (and when the loads112are operating) is provided to the system100from the load controllers114via a multiplexer116. Similarly, motor drives118are controlled by motor controllers120. Real-time data regarding which of the motor drives118are operating (and when the motor drives118are operating) is provided to the system100from the motor controllers120via the multiplexer116.

When loads are to be adjusted (such as at the block64(FIG.1)), the system100provides an appropriate control signal to a desired load controller114or a desired motor controller120via the multiplexer116. If larger groups of loads are to be controlled (such as by shutting down a portion of a transfer bus122), then the system100provides a control signal to a bus power control unit124which, in turn, controls the transfer bus122.

When the threshold profile is to be adjusted (such as at the block60(FIG.1)), the system100provides an appropriate control signal to a generator control unit126. The generator control unit126controls an electrical power generator128. The generator control unit126may be part of the electronic engine control system108or may be a standalone system, as desired.

In another exemplary embodiment, an energy storage device or devices may be used to power loads when the threshold levels32exceed electrical power generating capacity72and/or may be used to store electrical power when electrical power generating capacity72exceeds the threshold levels32. Referring back toFIG. 2, in this non-limiting example the threshold levels32exceed electrical power generating capacity72during the phases18,20,22,28, and30and electrical power generating capacity72exceeds the threshold levels32during the phases24and26.

Referring additionally toFIG. 7, in another exemplary embodiment a method200permits an energy storage device or devices (such as a capacitor bank, a bank of batteries, a flywheel energy storage device, or the like) to be used to power loads when the threshold levels32exceed electrical power generating capacity72and/or to store electrical power when electrical power generating capacity72exceeds the threshold levels32. The method200includes all of the processing blocks of the method10(FIG. 1). Therefore, for the sake of brevity details of the processing blocks of the method10(FIG. 1) will not be repeated. The same reference numbers for processing blocks of the method10(FIG. 1) are also used for the same processing blocks in the method200.

In the method200, when a determination is made at the decision block76that electrical power generating capacity72is less than the threshold levels32, processing continues to a decision block277at which a determination is made whether to use stored energy to power loads. If so, then at a block279the stored energy device(s) is used to power loads. Processing then continues to the block66. If not, then processing continues to the block60.

If electrical power generating capacity72is greater than the threshold levels32, then at a decision block281a determination is made whether to store energy in the energy storage device(s). If so, then at a block283energy is stored in the energy storage device(s). Processing then continues to the block66. If not, processing proceeds from the decision block281to the block66.

Referring additionally now toFIG. 8, in another exemplary embodiment a system300permits an energy storage device or devices330(such as a capacitor bank, a bank of batteries, a regenerative fuel cell, a flywheel energy storage device, or the like) to be used to power loads in an exemplary host environment302when the threshold levels32exceed electrical power generating capacity72and/or to store electrical power when electrical power generating capacity72exceeds the threshold levels32. The system300includes all of the processing components of the system100(FIG. 6) and the host environment302includes all of the components of the host environment102(FIG. 6). Therefore, for the sake of brevity details of the system100(FIG. 6) and the host environment102(FIG. 6) will not be repeated. The same reference numbers for components of the host environment102(FIG. 6) are also used for the same components of the host environment302.

When electrical power generating capacity72is less than the threshold levels32and a determination is made to use energy stored in the energy storage device(s)330to power loads, the system300provides a control signal to the energy storage device(s)330. In response to the control signal from the system300, the energy storage device(s)330use stored electrical power to power the loads. When electrical power generating capacity72is greater than the threshold levels32and a determination is made to store energy in the energy storage device(s), the system300provides a control signal to the energy storage device(s)330to store electrical power. In response to the control signal from the system300, the energy storage device(s)330store electrical power. The stored electrical power may be used as desired to power loads as described above.

While a number of exemplary embodiments and aspects have been illustrated and discussed above, those of skill in the art will recognize certain modifications, permutations, additions, and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, and sub-combinations as are within their true spirit and scope.