Method for controlling electrical system for electric hybrid turbine

Abstract

The invention relates to a method for controlling an electrical system, the method comprising: processing a main command signal (IP) for commanding the drawing of mechanical power by the electrical system from an electric hybrid turbine to extract from said signal a first frequency component (CF1) corresponding to a natural frequency of a first rotating body of the turbine, and generating a filtered first main signal (IF1) without the first frequency component (CF1); generating a first auxiliary command signal (CTRL1) for commanding the drawing of mechanical power from the first rotating body by the electrical system on the basis of the filtered first main signal (IF1); and generating a second auxiliary command signal (CTRL2, CTRL3) for commanding power to be drawn by the electrical system from the auxiliary power source based on the first frequency component (CF1).

Description

Technical Field

[0001] The present disclosure relates to the field of gas turbine engines, in particular aircraft engines. More specifically, the present disclosure relates to managing the power supply to electrical loads of the engine and / or aircraft. Background Art

[0002] The aircraft may include at least one engine, which may include at least two different rotating shaft systems. In addition, each of the engine and the aircraft may include an electrical load and / or a power source. The electrical system may connect the load, source, and engine together to allow electrical exchange between these different elements. In addition, the engine may include at least one motor connected to the rotating shaft system. Therefore, at least one of the loads may be supplied with power by the motor, for which the motor draws mechanical power from at least one of the rotating shaft systems. In addition, at least one of the rotating shaft systems may be assisted by drawing power from at least one source. In this case, the motor may be the source, and then mechanical power may be drawn from another rotating shaft system. Therefore, the rotating shaft system subjected to force by drawing or injecting mechanical power may include natural modes, such as torsion and / or bending. Therefore, drawing or injecting mechanical power at a frequency close to these natural modes may cause all or part of the engine to resonate, which may damage the engine. On the other hand, avoiding drawing or injecting mechanical power from the rotating shaft system due to these natural modes may reduce the performance of the electrical system, thereby reducing the performance of the engine or even the aircraft. Summary of the invention

[0003] An object of the present disclosure is to increase the service life of an aircraft engine including an electrical load supplied by drawing mechanical power from the engine while ensuring the performance of the engine.

[0004] To this end, according to one aspect of the present disclosure, a method for controlling an electrical system is proposed, comprising:

[0005] processing a main signal for commanding mechanical power to be drawn from the electric hybrid gas turbine engine by the electrical system to extract a first frequency component corresponding to a natural frequency of a first rotating shafting of the gas turbine engine from the main signal, and generating a filtered first main signal without the first frequency component;

[0006] generating a first auxiliary signal based on the filtered first primary signal, the first auxiliary signal for commanding the electrical system to extract mechanical power from the first rotating shaft system; and

[0007] A second auxiliary signal is generated based on the first frequency component, the second auxiliary signal being used to command power to be drawn by the electrical system from the auxiliary power source.

[0008] Advantageously, but optionally, the method may include at least one of the following features, taken alone or in any combination:

[0009] - the auxiliary power source is a second rotating shaft system of the gas turbine engine, and the generation of the second auxiliary signal comprises filtering the first frequency component to extract from the first frequency component a second frequency component corresponding to a natural frequency of the second rotating shaft system;

[0010] - the auxiliary power source is a second rotating shaft system of the gas turbine engine, the method further comprising:

[0011] * processing the primary signal to extract a second frequency component corresponding to a natural frequency of the second rotating shaft system from the primary signal and to generate a filtered second primary signal without the second frequency component;

[0012] * processing the filtered second main signal according to instructions for distributing the extraction of mechanical power between the first rotating shaft system and the second rotating shaft system to generate a filtered first intermediate signal and a filtered second intermediate signal, the filtered first intermediate signal being used to command the electrical system to extract mechanical power from the first rotating shaft system, and the filtered second intermediate signal being used to command the electrical system to extract mechanical power from the second rotating shaft system;

[0013] wherein generating the first auxiliary signal is achieved based on the second frequency component and the filtered first intermediate signal; and

[0014] wherein generating the second auxiliary signal is achieved based on the filtered second intermediate signal;

[0015] - the auxiliary power source is a second rotating shaft system of the gas turbine engine, the method further comprising pre-processing the main signal to extract from the main signal at least one third frequency component corresponding to a natural frequency common to the first rotating shaft system and the second rotating shaft system, and generating a filtered main intermediate signal, wherein the extraction of at least one of the first frequency component and the second frequency component is achieved by processing the filtered main intermediate signal;

[0016] - the method further comprises generating a third auxiliary signal based on the third frequency component, the third auxiliary signal being used to command the electrical system to draw power from the DC source;

[0017] - the auxiliary power source is a second rotating shaft system of the gas turbine engine, the method further comprising:

[0018] * processing the primary signal to extract a second frequency component corresponding to a natural frequency of the second rotating shaft system from the primary signal and to generate a filtered second primary signal without the second frequency component;

[0019] * generating a third auxiliary signal based on the first frequency component and the second frequency component, the third auxiliary signal being used to command power to be drawn from the DC source by the electrical system;

[0020] - the method also includes pre-processing the main signal based on instructions for distributing the extracted power between the first rotating shaft system, the second rotating shaft system and the DC source to generate a filtered first intermediate signal, a filtered second intermediate signal and a filtered third intermediate signal, the filtered first intermediate signal is used to command the electrical system to extract mechanical power from the first rotating shaft system, the filtered second intermediate signal is used to command the electrical system to extract mechanical power from the second rotating shaft system, and the filtered third intermediate signal is used to command the electrical system to extract power from the DC source, wherein the extraction of the first frequency component is achieved by processing the filtered first intermediate signal, the extraction of the second frequency component is achieved by processing the filtered second intermediate signal, and the generation of the third auxiliary signal is achieved based on the filtered third intermediate signal;

[0021] Generating one of the first auxiliary signal and the second auxiliary signal is achieved based on a maximum authorized draw threshold value for one of the first rotating shaft system and the auxiliary power source.

[0022] According to another aspect, there is provided an electrical system comprising:

[0023] a power supply bus intended to be connected to at least one load and configured to supply power to the load in the form of a DC signal;

[0024] a first AC generator intended to be connected to the first rotating shafting of the electric hybrid gas turbine engine in order to extract mechanical power from the first rotating shafting and convert it into electrical power capable of being transmitted to a bus;

[0025] a second AC generator intended to be connected to the second rotating shafting of the gas turbine engine in order to extract mechanical power from the second rotating shafting and to convert it into electrical power capable of being transmitted to the bus;

[0026] a first converter connecting the first AC generator to the bus and configured to regulate a bus voltage based on power supplied by the first AC generator;

[0027] a second converter connecting the second AC generator to the bus and configured to regulate the bus voltage based on power supplied by the second AC generator; and

[0028] A control device is connected to the converter and is configured to control the converter in order to compensate for the bus voltage variation by implementing the method as described above.

[0029] According to another aspect, there is provided a gas turbine engine comprising:

[0030] Electrical system as previously described;

[0031] a first rotating shafting connected to a first generator; and

[0032] A second rotating shafting is connected to a second generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages will appear from the following description, which is given by way of illustration only and not of limitation, and which should be read with reference to the accompanying drawings, in which:

[0034] Figure 1 An aircraft is shown schematically.

[0035] Figure 2 is a schematic cross-sectional view of a propulsion unit.

[0036] Figure 3 The electrical system is shown schematically.

[0037] Figure 4 An embodiment of a control method according to the present disclosure is shown.

[0038] Figure 5 An embodiment of a control method according to the present disclosure is shown.

[0039] Figure 6 An embodiment of a control method according to the present disclosure is shown.

[0040] Figure 7 An embodiment of a control method according to the present disclosure is shown.

[0041] Figure 8 An embodiment of a control method according to the present disclosure is shown.

[0042] Fig. 9 An embodiment of a control method according to the present disclosure is shown.

[0043] Fig.10 An embodiment of a control method according to the present disclosure is shown.

[0044] Similar elements have the same reference numerals throughout the drawings. DETAILED DESCRIPTION

[0045] Aircraft

[0046] Figure 1An aircraft 100 is shown, which includes at least one propulsion unit 1, in this example, the aircraft 100 includes two propulsion units 1. The aircraft 100 shown is a civilian or military aircraft, but it can also be any type of aircraft 100, such as a helicopter. The propulsion units 1 are attached and fixed to the aircraft 100, each propulsion unit being under a wing of the aircraft 100, as can be seen in FIG. Figure 1 However, this is not restrictive, since at least one propulsion unit 1 may also be mounted on a wing of the aircraft or even on the rear fuselage of the aircraft.

[0047] Aircraft 100 also includes a plurality of Figure 3 4. The electrical loads (or receivers) 400 shown in FIG. Each electrical load 400 is a device that is supplied with electrical energy and can be configured to convert the electrical energy that powers the device into another form of energy, such as thermal energy or mechanical energy. Non-limiting examples of electrical loads 400 of the aircraft 100 are: electric motors, heating and / or air conditioning systems, compressors, etc. In particular, these electrical loads 400 can ensure a certain number of functions in flight and on the ground, such as pressurization and / or lighting of the cabin of the aircraft 100, operation of the cockpit, etc.

[0048] In order to supply these electrical loads 400 with electrical energy, the aircraft 100 includes a plurality of electrical networks, at least one of which is a direct current network. Each electrical network generally includes a set of electrical conductors, generally a set of wires or strips and / or an assembly of wires and / or one (or more) printed tracks and / or any device for conducting electricity. A direct current (DC) network allows electrical energy to circulate only in the form of a DC signal.

[0049] The electrical energy 400 consumed by the electrical load 400 may be generated at least partly by an engine 2 of the propulsion unit 1 as will be described in more detail below, and more precisely by mechanical extraction from the rotating shafting BP, HP of the engine 2 .

[0050] Propulsion unit

[0051] Figure 2 A propulsion unit 1 is shown which extends along a longitudinal axis XX and comprises an engine 2 , which is a gas turbine engine, and a nacelle 3 around the engine 2 .

[0052] The propulsion unit 1 is intended to be installed on an aircraft 100, for example Figure 1 The manner shown is mounted on an aircraft 100. To this end, the propulsion unit 1 may include a mast (not shown) for connecting the propulsion unit 1 to a part of the aircraft 100.

[0053] Figure 2The engine 2 shown in the figure is a twin-shaft turbofan engine directly driven by a fan 20. However, this is not restrictive, since the engine 2 may have a different number of shafting and / or flow, and / or be another type of turbojet, such as a turbojet or turboprop with a fan driven via a speed reducer. Similarly, what is described applies to all types of gas turbine engines, in other words, to all types of systems capable of transferring energy between rotating parts and fluids.

[0054] Unless otherwise stated, the terms "upstream" and "downstream" are used relative to the general direction 1 of the airflow through the propulsion unit 1 in operation. Similarly, the axial direction corresponds to the direction of the longitudinal axis XX and the radial direction is a direction orthogonal to the longitudinal axis XX and intersecting the longitudinal axis XX. Furthermore, an axial plane is a plane containing the longitudinal axis XX, while a radial plane is a plane orthogonal to the longitudinal axis XX. A circumference refers to a circle that is in the radial plane and has its center on the longitudinal axis XX. A tangential or circumferential direction is a direction tangential to the circumference: a tangential or circumferential direction is orthogonal to the longitudinal axis XX but does not pass through the longitudinal axis XX. Finally, the adjectives "inner" (or "inside") and "outer" (or "outside") are used relative to the radial direction, so that in the radial direction, an inner part of an element is closer to the longitudinal axis XX than an outer part of the same element.

[0055] from Figure 2 As can be seen from the figure, the engine 2 includes, from upstream to downstream: a fan 20; a compression section 22, the compression section includes a low-pressure compressor 220 and a high-pressure compressor 222; a combustion chamber 24; and an expansion section 26, the expansion section includes a high-pressure turbine 262 and a low-pressure turbine 260. Each of the low-pressure compressor 220, the high-pressure compressor 222, the high-pressure turbine 262 and the low-pressure turbine 260 includes a rotor portion and a stator portion, and the rotor portion can be driven to rotate around the longitudinal axis XX relative to the stator portion. The fan 20, the rotor portion of the low-pressure compressor 220, and the rotor portion of the low-pressure turbine 260 are connected to each other by a low-pressure shaft 280 extending along the longitudinal axis XX, thereby forming a low-pressure shaft system (shaft system BP), which is a first rotating shaft system. The rotor part of the high-pressure compressor 222 and the rotor part of the high-pressure turbine 262 are connected to each other via a high-pressure shaft 282, which likewise extends around the low-pressure shaft 280 along the longitudinal axis XX, thereby forming a high-pressure shaft system (shaft system HP), which is a second rotating shaft system. Figure 2As can be seen in the figure, the compression section 22, the combustion chamber 24 and the expansion section 26 are surrounded by the engine casing 23, the stator portion of the low-pressure compressor 220, the stator portion of the high-pressure compressor 222, the stator portion of the high-pressure turbine 262 and the stator portion of the low-pressure turbine 260 are connected to the engine casing 23, and the fan 20 is surrounded by the fan casing 25. The engine casing 23 and the fan casing 25 are connected to each other by radially extending profile arms 27, which form outlet guide vanes (Outlet Guide Vanes, OGV), and the profile arms 27 are distributed circumferentially around the longitudinal axis XX. At least some of these arms 27 can be intended to be structural. The longitudinal axis XX defines the rotor components of the compression section 22, the rotor components of the expansion section 26 and the rotation axis of the fan 20. In other words, the shaft system BP and the shaft system HP can each rotate relative to the engine casing 23 and the fan casing 25 around the longitudinal axis XX.

[0056] The nacelle 3 extends radially outside the engine 2, all around the longitudinal axis XX, to surround both the fan casing 25 and the engine casing 23 and to define, together with the downstream portion of the engine casing 23, the downstream portion of the secondary duct B, the upstream portion of which is defined by the fan casing 25 and the upstream portion of said engine casing 23. The upstream portion of the nacelle 3 further defines an air inlet 29 through which the fan 20 sucks the air flow circulating through the propulsion unit 1. The nacelle 3 is integral with the fan casing 25 and is attached and fixed to the aircraft 100 by a mast.

[0057] The engine 2 may also include at least one accessory gearbox (Accessory gear box, AGB) (not shown), which is usually housed in a cavity arranged in the nacelle 3. The accessory gearbox includes a set of gears that enable multiple shafts to rotate around their own axes, and the accessories are mounted on these shafts to obtain useful mechanical power from the rotation of the shafts. The set of gears itself is driven using a radial drive shaft (Radial Drive Shaft, RDS), which optionally connects the accessory gearbox to at least one of the high-pressure shaft system HP and the low-pressure shaft system BP via a transfer case (not shown), and the high-pressure shaft system HP and the low-pressure shaft system BP are usually meshed with at least one of the high-pressure shaft 282 and the low-pressure shaft 280. To this end, the radial drive shaft can extend in a longitudinal cavity arranged in one of the arms 27. In this way, mechanical power can be drawn from at least one of the high-pressure shaft system HP and the low-pressure shaft system BP to be delivered to at least one of the accessories via the accessory gearbox.

[0058] The engine 2 itself may also include a plurality of electrical loads 400, such as a starter, a variable geometry or a de-icing system, which also must be provided with electrical energy. The power source of at least some of these electrical loads 400 may be in the form of a DC signal, typically a DC voltage.

[0059] In operation, the fan 20 sucks in an air flow, a portion of which circulates in the main duct A is continuously compressed in the compression section 22, ignited in the combustion chamber 24 and expanded in the expansion section 26 before being ejected from the engine 2. The main duct A passes through the engine case 23 from one side to the other. Another portion of the air flow circulates in the secondary duct B, which has an elongated annular shape surrounding the engine case 23, and the air sucked in by the fan 20 is straightened by a flow straightener and then discharged from the propulsion unit 1. In this way, the propulsion unit 1 generates thrust. This thrust can be used for the benefit of, for example, the aircraft 100, to which the propulsion unit 1 is attached and fixed.

[0060] Electrical System

[0061] Figure 3 An electrical system 4 is shown, which is distributed between the propulsion unit 1 and the aircraft 100 for supplying electrical energy to the engine 2 and / or the electrical loads 400 of the aircraft 100, usually by means of a DC network. In particular, the electrical system 4 can create an interface between the rotating shaft system BP, HP of the engine 2 and the electrical network of the aircraft 100. In particular, the electrical system is configured to respond to the power demand of the aircraft 100 and / or the loads 400 of the engine 2 by mechanically extracting from the engine 2, to use the power supply of the aircraft 100 and / or the engine 2 to assist the start-up and / or in-flight operation of the engine 2, and / or to ensure the power distribution between the rotating shaft system BP, HP of the engine 2. In other words, the engine 2 is an electric hybrid.

[0062] The electrical system 4 comprises an electrical bus 40 or power bus 40 connected to at least one electrical load 400 of the aircraft 100 and / or the engine 2, preferably to an assembly of a plurality of loads 400 of the aircraft 100 and / or the engine 2, the bus 40 being configured to supply electrical power to the load 400 in the form of a DC signal, in particular in response to the power demand of the load. In other words, the bus 40 is configured to allow the circulation of electrical energy in the form of a DC signal. The bus 40 may, for example, comprise a set of electrical conductors, typically a set of wires or wire rods and / or wire assemblies and / or one (or more) printed tracks and / or any device for conducting electricity.

[0063] The electrical system 4 further comprises a plurality of electrical converters 410, 420, 430, each of which is connected to a respective power source 411, 421, 431, in other words, to an element configured to supply electrical power. The power sources 411, 421, 431 may be alternating current (AC) generators 411, 421 and / or DC sources 431. The AC generators 411, 421 and the DC sources 431 may belong to the engine 2, in other words, the AC generators 411, 421 and the DC sources 431 are controlled simultaneously with the engine 2 or even controlled by the engine 2. In the present example, these power sources are the power sources 411, 421, 431 of the engine 2. Furthermore, the DC source 431 is not necessarily located in the engine 2 but may be housed, for example, in a mast which makes it possible to fix the engine 2 to the aircraft 100. Alternatively, the DC source 431 belongs to the aircraft 100, in other words, the DC source 431 is controlled simultaneously with the aircraft 100. From Figure 3 As can be seen in FIG. 4 , the electrical system 4 may thus include a first converter 410 connected to a first AC generator 411, a second converter 420 connected to a second AC generator 421, and, optionally, a third converter 430 connected to a DC source 431. The third converter 430 and the DC source 431 are optional, in some embodiments they are not present, or in other embodiments the DC source 431 is not available. On the other hand, as Figure 3 As can be seen in the figure, each of the converters 410, 420, 430 is connected to the bus 40. In fact, at least one (but not each) of the converters 410, 420, 430 is configured to adjust the voltage of the bus 40 based on (in other words, using) the power supplied by one or more power sources 411, 421, 431 to which the converters 410, 420, 430 are connected. Of course, the number and type of converters 410, 420, 430 and power sources 411, 421, 431 are not limiting.

[0064] The bus 40 voltage regulation is critical. More specifically, during the operation of the electrical system 4, the variation of the voltage in the bus 40 over time, although it may temporarily vary around a given nominal value, must still be kept within the limits of a certain margin, which guarantees the correct operation of all components connected to the bus 40. The margin defines the upper and lower limits of the voltage excursion according to time during the operation of the electrical system 4. The margin may include defined limits for normal and / or abnormal operating conditions, which symmetrically or otherwise surround the nominal voltage level of the bus 40. In the diagrams (not shown) giving the voltage variation according to time, the limits of the margin are generally represented as dashed or non-dashed lines. Preferably, even if the limit does not initially define a constant voltage value, in particular during the characteristic time for putting the electrical system 4 into operation (or startup) or during the time for establishing a permanent state in the case of power transients, the limit will generally subsequently define a constant voltage value, and this is to ensure the operational stability of the bus 40, and therefore, the operational stability of the electrical system 4. For example, such a margin may be defined in standards relating to the quality of the electrical system 4 and / or the DC network, but also be limited by the specifications of the aircraft-type vehicle to which the electrical system 4 is connected, typically by the requirements of the manufacturer of the aircraft 100 and / or the engine 2 in which the electrical system 4 is incorporated.

[0065] On the other hand, the voltage regulation of the bus 40 makes it possible to respond to the power demand of the load 400 connected to the bus 40. In general, when the amount of power drawn by at least one load 400 on the bus 40 is greater than the amount of power injected into the bus 40 by at least one converter 410, 420, 430, the voltage of the bus 40 drops significantly. On the contrary, when the amount of power injected into the bus 40 by at least one converter 410, 420, 430 is greater than the amount of power drawn from the bus 40 by at least one load 400, the voltage of the bus 40 increases. Therefore, regulating the voltage of the bus 40 makes it possible to respond to the power demand of the load 400 in addition to ensuring the safety of the electrical system 4. In other words, each of the converters 410, 420, 430 is configured to continuously adjust the power injected into or drawn from the bus 40 according to the voltage of the bus 40 to accurately respond to the power demand of the load 400 connected to the bus 40.

[0066] It is possible to inject power into or extract power from the bus 40 by the converters 410, 420, 430, which is achieved in particular by connecting the converters to the power sources 411, 421, 431. In fact, at least one of the AC generators 411, 421 (but not each) is connected to the rotating shaft system BP, HP of the engine 2 to be able to exchange mechanical power and / or electric power between the rotating shaft system BP, HP and the AC generators 411, 421, preferably extracting mechanical power from the rotating shaft system BP, HP and converting it into electric power, which is then delivered to the first converter 410 and / or to the second converter 420 to be injected into the bus 40. Since the power provided by the AC generators 411, 421 is in the form of an AC signal, each of the first converter 410 and the second converter 420 is configured to reversibly transform this AC signal into a DC signal suitable for injection into the bus 40 and then circulating on the bus 40. Similarly, the DC source 431 can deliver power in the form of a DC signal to the third converter 430, which still reversibly converts the power to give it a certain shape according to the constraints specific to the bus 40, and then injects the power into the bus 40. Each or at least one of the AC generators 411, 421 can be, for example, a winding rotor synchronous generator driven by at least one of the high-pressure shaft 282 and the low-pressure shaft 280 of the engine 2 (usually with the help of an accessory gearbox), a winding rotor synchronous generator usually including three stages, called a variable frequency generator (VFG). Other types of generators are also possible, preferably, such as a permanent magnet synchronous generator drive called PMSM (which has the advantage of a smaller mass in particular), or such as an induction generator or a variable reluctance generator. Preferably, the first AC generator 411 is connected to the shaft system HP, while the second AC generator 421 is connected to the shaft system BP, 280. The DC source 431 can include a battery, a supercapacitor, a DC generator and / or a fuel cell. The DC source 431 can in particular release the rotating shaft system BP, HP, or a relay that takes over the rotating shaft system BP, HP when, for example, the extraction level required to respond to the power demand of the load 400 is too high, and also makes it possible to absorb certain dynamics (such as sudden changes in the behavior of the load 400).

[0067] Figure 3 The electrical system 4 is also shown to include a control device 412 , 422 , 432 , 4000 connected to at least one (if not each) of the converters 410 , 420 , 430 .

[0068] Figure 3The control device 412, 422, 432, 4000 shown in FIG. 4 includes a central member 4000 and a plurality of control members 412, 422, 432, each of which is connected to (or incorporated in) one of the converters 410, 420, 430. Alternatively, the control device 412, 422, 432 may include only the plurality of control members 412, 422, 432, each of which is connected to (or incorporated in) one of the converters 410, 420, 430.

[0069] The control device 412, 422, 432, 4000 is also advantageously configured to receive a signal V representing a voltage measurement of the bus 40. To do this, the control device 412, 422, 432, 4000 can be connected to the bus 40 or to a voltage sensor 40 connected to the bus 40 and receive a signal V from the bus 40 (or from the sensor). This signal V can be received via a physical or wireless connection. This signal V is in particular representative of a change in the power demand of a portion of the load 400 connected to the bus 40. Typically, when the load 400 suddenly needs to be able to draw a large amount of power from the bus 40, due to the response time of the power required by the electrical system 4 to supply the bus 40 with the power drawn to compensate, the voltage of the bus 40 will suddenly drop, and this drop will be reported to the control device 412, 422, 432, 4000 via the signal V. In the same way, when a load 400 suddenly consumes a large amount of power on the bus 40, due to the response time of the electrical system 4 to extract the necessary power from the bus 40 in order to compensate for this consumption, the voltage of the bus 40 will suddenly increase, and this increase will be reported to the control device 412, 422, 432, 4000 via the signal V. Therefore, the signal V is usually a time signal, in other words, it provides (or represents) the change in the voltage of the bus 40 according to time. A large number of loads 400, in particular so-called "active" loads 400, can have this type of dynamic behavior, which may also change during various flight phases.

[0070] The changes in the voltage of the bus 40 are compensated by the action of the converters 410, 420, 430, which therefore follows the changes in voltage, no matter how sudden and fluctuating they may be. The action is therefore coordinated by the control means 412, 422, 432, 4000 to maintain the voltage of the bus 40 within a range that enables the electrical system 4 to operate stably.

[0071] To this end, each of the converters 410, 420, 430 receives a command signal CTRL_1, CTRL_2, CTRL_3 specific to the converter from the control device 412, 422, 432, 4000, and the converters 410, 420, 430 regulate the voltage of the bus 40 based on the command signal. Thus, the combination of the voltage regulation of each converter 410, 420, 430 makes it possible to continuously monitor the power demand of the load 400.

[0072] exist Figure 3 In the electrical system 4 shown in FIG. 4 , the central component 4000 is particularly configured to receive a signal V and subsequently process the signal V. Furthermore, the central component 4000 is configured to send a command signal CTRL_1, CTRL_2, CTRL_3 to each of the control components 412, 422, 432, which command signal can generally have the form of a command current for controlling the converters 410, 420, 430. Figure 3 In the electrical system 4 shown in FIG. 4 , the control is therefore performed in a centralized manner. Alternatively, when the control device 412, 422, 432 comprises only control members 412, 422, 432, each of the control members 412, 422, 432 is specifically configured in sequence to receive and process the signal V and control the converters 410, 420, 430. In other words, then, the control is performed in a decentralized manner.

[0073] Figure 3Additionally shown is the presence of a master controller 7, which may be, for example, all or part of a system (or FADEC or “Full Authority Digital Engine Control”) that generates an interface between the cockpit of the aircraft 100 and the engines 2. This is typically a control unit for the engines 2, (or an “Electronic Control Unit”, ECU), which is incorporated into the FADEC. The master controller 7 is connected to the control means 412, 422, 432, 4000, in the present example to the central member 4000, but may alternatively be directly connected to each of the control members 412, 422, 432 when the central member 4000 is absent. In this case, the functions performed by the central member 4000 are either performed locally in the control members 412, 422, 432 or by the master controller 7. In particular, the master controller 7 provides data DFP related to the natural frequencies of the rotating shaft systems BP, HP and additional constraints to be observed by the electrical system 4 in order to respond to the power requirements of the loads 400. Thus, the master controller 7 can send to the control means 412, 422, 432, 4000 instructions Cons for distributing the extraction between the rotating shafts BP, HP and the DC source 431, and / or maximum extraction thresholds Se1, Se2, Se3 on at least one (but not each) of the rotating shafts BP, HP and the DC source 431, the thresholds Se1, Se2, Se3 being specific to each rotating shaft BP, HP and DC source 431, where appropriate. More precisely, the distribution instructions Cons indicate to the control means 412, 422, 432, 4000 the manner in which the total power to be extracted from the engine 2 in order to respond to the demands of the load 400 must be distributed between the rotating shafts BP, HP and the DC source 431, and can generally take the form of percentages. The extraction thresholds Se1, Se2, Se3 provide a portion of the power sources 411, 421, 431 and each of the control devices 412, 422, 432, 4000 with the maximum value of the power that is authorized to be extracted by its respective converter, namely: a first maximum power value that can be extracted from the engine 2 by the first converter 410 via the first AC generator 411, a second maximum power value that can be extracted from the engine 2 by the second converter 420 via the AC second generator 421, and a third maximum power value 431 that can be extracted from the DC source 431 by the third converter 430. The threshold Se3 associated with the DC source 431 may typically take the form of a charge or discharge current extraction limit in the case where the DC source 431 is a battery.Then, the control device 412, 422, 432, 4000 is configured to control the converter 410, 420, 430 as a function of the DFP data related to the natural frequency of the rotating shaft systems BP, HP, the distribution command Cons and / or the threshold values ​​Se1, Se2, Se3.

[0074] The data DFP related to the natural frequency of the rotating shaft system BP, HP, the distribution instruction Cons and / or the threshold values ​​Se1, Se2, Se3 for extraction transmitted by the master controller 7 can vary over time and can ensure that each of the rotating shaft system BP, HP and the DC source 431 supplies the necessary power to the load by optimizing the operating point of the engine 2. In any case, these data DFP related to the natural frequency of the rotating shaft system BP, HP, the distribution instruction Cons and / or these threshold values ​​Se1, Se2, Se3 for extraction can prove to be necessary in the case where the mechanical extraction has different results depending on the rotating shaft system BP, HP from which the power is extracted.

[0075] Control Methods

[0076] Figures 4 to 10 Different embodiments of a control method for an electrical system 4 are shown. Figure 3 The control devices 412, 422, 432, 4000 shown in the figure are implemented in order to enable a real-time response to the power demand of the electrical load 400 regardless of the operating phase of the engine 2, while complying with constraints specific to the engine 2, in particular constraints specific to the rotating shaft system BP, HP of the engine 2.

[0077] The control method aims to prevent the rotating shaft system BP, HP, in particular the shafts 280, 282, from being stressed in their natural modes, usually in torsion and / or bending (i.e., mechanical stretching of the AC generators 411, 421). These natural modes are associated with natural frequencies and have the characteristic of accumulating mechanical energy to potentially drive vibrations that can damage the associated components. By means of the control method, the electrical system 4 does not subject the rotating shaft system BP, HP to stresses at frequencies close to these natural frequencies, for example, by torque. To this end, as will be described in detail below, the control method enables the switching of unwanted frequency content drawn from one rotating shaft system BP, HP to another power source 411, 421, 431, which makes it possible to maximize the power drawn by the electrical system 4 on the rotating shaft system BP, HP without the risk of reducing its service life.

[0078] Figures 4 to 10This control method is shown implemented in the central member 4000, however, this is not restrictive, as the control method can be implemented in one (not in each) of the control members 412, 422, 432. If this is the case, the control members 412, 422, 432 can exchange information between them in the form of wired or remote signals, and / or receive information from the bus 40 and / or the overall controller 7.

[0079] This control method enables the electrical system 4 to correct the difference (or error) detected between the reference V_ref, which depends on the voltage margin 40 of the bus 40, representing the state in which the bus 40 should be for normal operation, and which can be transmitted by the master controller 7, and the voltage measurements of the bus 40, which represent the actual situation of the demands of the electrical loads 400 as they are represented by injecting power into or extracting power from the bus 40. In other words, this control method ensures that the power demand of the electrical loads 400 is met by the voltage regulation of the bus 40 by correcting the difference between the reference V_ref and the voltage measurements of the bus 40.

[0080] More precisely, if Figures 4 to 10As shown in , a voltage signal V is received, which represents the voltage measurement result of the bus 40. Then, the voltage signal V can be compared with the reference V_ref. If there is no difference between the reference V_ref and the voltage signal V, it means that the voltage of the bus 40 has not been regulated. On the contrary, if a difference is observed, in other words, if the voltage of the bus 40 has changed, it is necessary for the voltage of the bus 40 to be regulated. To this end, it is necessary to control the power supplies 411, 421, 431 to produce such voltage regulation. This control can, for example, include transmitting command current, command power or even command torque. These command signals CTRL_1, CTRL_2, CTRL_3 will determine the way in which the electrical system 4 (more precisely, the power supplies 411, 421, 431) will have to adjust its operation to achieve this voltage regulation. In this case, it can be advantageous to generate an initial command signal I0 based on the error indicated in the voltage signal V relative to the reference V_ref and then process the initial command signal I0, which is easier to be used by the control member (whether it is the central member 4000 or the control member 412, 422, 432). This process can advantageously be implemented by a proportional-integral corrector. Thus, the main signal IP for commanding the electrical system 4 to extract mechanical power on the electric hybrid engine 2 is ready to arrive at the electrical system 4. This main command signal IP represents the correction to be applied by the electrical system 4 to reduce or even eliminate the difference between the reference V_ref and the measured signal, thus compensating for the variation in the voltage of the bus 40. However, this main command signal IP only sets a general instruction to be adopted by the electrical system 4, without distinguishing the role of each of the components of the electrical system 4, and more precisely, the power sources 411, 421, 431 will have to play a role in the voltage regulation of the bus 40.

[0081] For this purpose, refer to Figure 4, processing the main command signal IP to extract from the main command signal a first frequency component CF1 corresponding to the natural frequency of the first rotating shaft system (for example the shaft system HP), and generating a first filtered main signal IF1 without the first frequency component CF1. For this purpose, for example, a band-stop filter or a low-pass filter can be used, or even a plurality of band-pass and / or low-pass filters combined and / or associated with each other can be used. These filters can be of several types or orders. The filter can have a fixed structure, or a variable topology as a function of several parameters associated with data DFP, which are related to the natural frequency of the rotating shaft system BP, HP and are, for example: the rotation speed of the engine 2, at least one of the fuel flow rates in the combustion chamber 24, the position of the variable geometry, the flight conditions of the aircraft 100, the level of mechanical power drawn from the rotating shaft system BP, HP, etc. In this way, it is possible to take into account the potential changes in the natural mode of the rotating shaft system BP, HP in operation and to adjust the exclusion of the first frequency component CF1 accordingly.

[0082] Thus, based on the filtered first main signal IF1, a first auxiliary signal CTRL_1 is generated for commanding the extraction of mechanical power from the first rotating shaft system HP by the electrical system 4, and more precisely by the first AC generator 411. The generation of the first auxiliary command signal CTRL_1 may simply consist in formatting the filtered first main signal IF1 so that it corresponds to the specific constraints of the control member 412 associated with the first AC generator 411. Alternatively or additionally, as in Figure 4 As can be seen in FIG. 1 , this generation can also be realized on the basis of a first authorized maximum threshold Se1 for extraction from the first rotating shaft system HP, which first authorized maximum threshold Se1 can usually also be transmitted by the overall controller 7. Thus, the first auxiliary command signal CTRL_1 corresponds to a command signal transmitted to the control member 412 of the converter 410 connected to the first AC generator 411 that extracts power from the first rotating shaft system HP.

[0083] Furthermore, a second auxiliary signal CTRL_2 is generated based on the first frequency component CF1, which is used to command the electrical system 4 to extract power from the auxiliary power source BP, 431. Thus, the natural frequency of the disturbance to the first rotating shaft system HP, which is contained in the main command signal IP, is eliminated on the auxiliary power source BP, 431. Again, the generation of the second auxiliary command signal CTRL_2, CTRL_3 may simply consist in formatting the first frequency component CF1 so that it corresponds to a specific constraint of the control member 422, 432, which is associated with the auxiliary power source BP, 431. Alternatively or additionally, the generation may also be implemented based on a maximum authorized extraction threshold Se2, Se3 from the auxiliary power source BP, 431, which may also be transmitted by the master controller 7 in general. The auxiliary power source BP, 431 may be a second rotating shaft system, typically the shaft system BP of the engine 2, but may also be a DC source 431. Therefore, the second auxiliary command signals CTRL_2, CTRL_3 correspond to the command signal of the control component 422 transmitted to the converter 420 or to the command signal of the control component 432 transmitted to the converter 430, wherein the converter 420 is connected to the second AC generator 421, which draws power from the second rotating shaft system BP, and the converter 430 is connected to the DC source 431.

[0084] Figure 5 It is shown that in the case where the auxiliary power source BP, 431 is the second rotating shaft system BP of the engine 2, the generation of the second auxiliary command signal CTRL_2 may include filtering the first frequency component CF1 to extract the second frequency component CF2 from the first frequency component, the second frequency component CF2 corresponding to the natural frequency of the second rotating shaft system BP. In this way, it is ensured that the interfering frequency content of the first rotating shaft system HP (which is eliminated on the second rotating shaft system BP) also does not contain any interfering natural frequency of the second rotating shaft system BP. Again, the exclusion of the second frequency component CF2 can be achieved using a filter equivalent to the filter already disclosed based on data DFP related to the natural frequency of the rotating shaft system BP, HP transmitted, for example, by the overall controller 7.

[0085] Figure 6It is shown that a third auxiliary signal CTRL_3 can be generated based on the second frequency component CF2, which is used to command the extraction of power from the DC source 431. Therefore, the third auxiliary command signal CTRL_3 corresponds to a command signal transmitted to a control member 432, which is associated with a converter 430 connected to the DC source 431. Therefore, the interfering natural frequency of the second rotating shaft system BP contained in the first frequency component CF1 is eliminated on the DC source 431. Here too, the generation of the third auxiliary command signal CTRL_3 can be realized based on a maximum authorized extraction threshold Se3 from the DC source 431, which can also generally be transmitted by the master controller 7. By this alternative embodiment, almost all of the required power via the main signal IP will be effectively extracted by the electrical system 4 from the power sources 411, 421, 431, which makes it possible to optimize the performance of the electrical system 4 for voltage regulation.

[0086] Figures 7 to 10 Various alternatives of the control method are shown in , in which a distribution instruction Cons is used for distributing the extraction between the rotating shaft systems BP, HP and the DC source 431 .

[0087] Figure 7 Shows Figure 4 An alternative to the embodiment shown in , in which the auxiliary power source BP, 431 is the second rotating shaft system BP of the engine 2. Figure 7 As can be seen, the main signal IP is also processed to extract the second frequency component CF2 corresponding to the natural frequency of the second rotating shaft system BP from the main signal and generate a filtered second main signal IF2 without the second frequency component CF2. The filtered second main signal IF2 is then processed based on the allocation instruction Cons for allocating the mechanical power to be extracted between the first rotating shaft system HP and the second rotating shaft system BP to generate a filtered first intermediate signal IIF1 and a filtered second intermediate signal IIF2, the filtered first intermediate signal being used to command the electrical system 4 to extract mechanical power from the first rotating shaft system HP, and the filtered second intermediate signal being used to command the electrical system 4 to extract mechanical power from the second rotating shaft system BP. At this point, the first auxiliary command signal CTRL_1 is generated based on the second frequency component CF2 and the filtered first intermediate signal IIF1. Similarly, the second auxiliary command signal CTRL_2 is generated in addition to being generated based on the configuration as already referred to. Figure 4In addition to the first frequency component CF1 described, it is also generated according to the filtered second intermediate signal IIF2. Therefore, the filtered second main signal IF2 avoids the interference frequency content of the two rotating shaft systems BP and HP, which makes it possible to ensure that the filtered second main signal IF2 is safe, and the filtered second main signal is processed by the distribution instruction Cons for distributing the mechanical power extraction between the first rotating shaft system HP and the second rotating shaft system BP. In addition, in order to ensure maximum performance, the interference frequency content of one of the rotating shaft systems BP and HP is reincorporated into the command signal of the control member 412, 422 associated with the converter 412, 422 connected to the AC generator 411, 421 of the other rotating shaft system in the rotating shaft system BP and HP, and vice versa. Here too, the generation of the first auxiliary command signal CTRL_1 and the generation of the second auxiliary command signal CTRL_2 may simply consist of formatting the filtered first intermediate command signal IIF1 and the filtered second intermediate command signal IIF2, respectively, so that they correspond to the specific constraints of the control members 412, 422 associated with the converters 412, 422 connected to the AC generators 411, 421. Alternatively or additionally, the generation may also be implemented based on a first maximum authorized extraction threshold Se1 of the first rotating shaft system HP and a second maximum authorized extraction threshold Se2 of the second rotating shaft system BP, respectively, which thresholds may also generally be transmitted by the overall controller 7.

[0088] Figure 8 Shown with Figure 7 A variation similar to the embodiment shown in , except that the interfering frequency content common to the rotating axis systems BP, HP is filtered in advance. More specifically, such frequency content cannot be eliminated on either of the rotating axis systems BP, HP. More precisely, the main signal IP is pre-processed to extract from the main signal at least a third frequency component CF3 corresponding to the natural frequency common to the first rotating axis system HP and the second rotating axis system BP and to produce a filtered main intermediate signal IP, wherein the extraction of at least one of the first frequency component CF1 and the second frequency component CF2 is achieved by processing the filtered main intermediate signal IP. Again, the exclusion of the third frequency component CF3 can be achieved using a filter equivalent to the filter already disclosed based on data DFP related to the natural frequency of the rotating axis systems BP, HP transmitted, for example, by the main controller 7.

[0089] Fig. 9 Shows Figure 8, wherein the interfering frequency content common to the two rotating shaft systems BP, HP is removed by the DC source 431 to avoid power losses, thereby improving the voltage regulation performance. More precisely, the third auxiliary command signal CTRL_3 for commanding the electrical system 4 to draw power from the DC source 431 is generated based on the extracted third frequency component CF3. Again, the generation of the third auxiliary command signal CTRL_3 can be achieved based on the maximum authorized drawing threshold Se3 from the DC source 431, which can also be generally transmitted by the master controller 7.

[0090] Fig.10 Shows Figure 4 A variation of the embodiment shown, in which all interfering frequency contents are removed by the DC source 431, instead of sending them to another rotating shaft system HP, BP. More precisely, the auxiliary power source BP, 431 is the second rotating shaft system BP of the engine 2, the main signal IP is processed to extract the second frequency component CF2 corresponding to the natural frequency of the second rotating shaft system BP from the main signal, and a filtered second main signal IF2 without the second frequency component CF2 is generated. In addition, a third auxiliary command signal CTRL_3 for commanding the electrical system 4 to draw power from the DC source 431 is generated based on the first frequency component CF1 and the second frequency component CF2. Again, the generation of the third auxiliary command signal CTRL_3 can be implemented based on the maximum authorized drawing threshold Se3 from the DC source 431, which can also be generally transmitted by the master controller 7. Similarly, the exclusion of the second frequency component CF2 can be implemented using a filter equivalent to the filter already disclosed based on data DFP related to the natural frequency of the rotating shaft system BP, HP, for example transmitted by the master controller 7.

[0091] Fig.10It is also shown that the command Cons for distributing the extraction of power between the first rotating shaft system HP, the second rotating shaft system HP and the DC source 431 can also be used. More precisely, the main command signal IP is pre-processed based on the command Cons for distributing the extracted power between the first rotating shaft system HP, the second rotating shaft system BP and the DC source 431 to generate a filtered first intermediate signal IIF1 for commanding the electrical system 4 to extract mechanical power from the first rotating shaft system HP, a filtered second intermediate signal IIF2 for commanding the electrical system 4 to extract mechanical power from the second rotating shaft system BP, and a filtered third intermediate signal IIF3 for commanding the electrical system 4 to extract power from the DC source 431. In addition, the extraction of the first frequency component CF1 is achieved by processing the filtered first intermediate signal IIF1, the extraction of the second frequency component CF2 is achieved by processing the filtered second intermediate signal IIF2, and the generation of the third auxiliary command signal CTRL_3 is achieved based on the filtered third intermediate signal IIF3.

[0092] In any case, and as Figure 3 As can be seen in FIG. 4 , each converter 410 , 420 , 430 is controlled by its respective control means 412 , 422 , 432 using an auxiliary command signal CTRL_1 , CTRL_2 , CTRL_3 dedicated thereto, in order to compensate for its part of the voltage variation.

[0093] Advantages gained

[0094] By means of the control method described above, the mechanical extraction of power from the electric hybrid engine 2 does not risk exciting the natural modes of the shafts 280 , 282 of the engine 2 , while minimizing the power losses associated with excluding these natural modes in the implementation of the power extraction and, therefore, minimizing the performance losses.

Claims

1. A method for controlling an electrical system (4) for an electric hybrid gas turbine engine (2), the method comprising: processing a main signal (IP) for commanding the electrical system (4) to extract mechanical power from the gas turbine engine (2) to extract from the main signal a first frequency component (CF1) corresponding to a natural frequency of a first rotating shaft (HP) of the gas turbine engine (2), and generating a filtered first main signal (IF1) without the first frequency component (CF1); generating a first auxiliary signal (CTRL_1) based on the filtered first main signal (IF1), the first auxiliary signal being used to command the electrical system (4) to extract mechanical power from the first rotating shaft system (HP); and A second auxiliary signal (CTRL_2, CTRL_3) is generated based on the first frequency component (CF1), the second auxiliary signal being used to command the electrical system (4) to draw power from an auxiliary power source (BP, 431).

2. The method according to claim 1, wherein: The auxiliary power source (BP, 431) is a second rotating shaft system (BP) of the gas turbine engine (2), and generating the second auxiliary signal (CTRL_2) includes filtering the first frequency component (CF1) to extract a second frequency component (CF2) corresponding to the natural frequency of the second rotating shaft system (BP) from the first frequency component.

3. The method according to claim 1, wherein: The auxiliary power source (BP, 431) is a second rotating shaft system (BP) of the gas turbine engine (2), the method further comprising: processing the primary signal (IP) to extract from the primary signal a second frequency component (CF2) corresponding to a natural frequency of the second rotating shaft system (BP) and generating a filtered second primary signal (IF2) without the second frequency component (CF2); processing the filtered second main signal (IF2) according to an instruction (Cons) for distributing the extraction of mechanical power between the first rotating shaft system (HP) and the second rotating shaft system (BP) to generate a filtered first intermediate signal (IIF1) and a filtered second intermediate signal (IIF2), the filtered first intermediate signal being used to command the electrical system (4) to extract mechanical power from the first rotating shaft system (HP), and the filtered second intermediate signal being used to command the electrical system (4) to extract mechanical power from the second rotating shaft system (BP); wherein generating the first auxiliary signal (CTRL_1) is achieved based on the second frequency component (CF2) and the filtered first intermediate signal (IIF1); and wherein generating the second auxiliary signal (CTRL_2) is achieved based on the filtered second intermediate signal (IIF2).

4. The method according to any one of claims 1 to 3, wherein: The auxiliary power source (BP, 431) is the second rotating shaft system (BP) of the gas turbine engine (2), and the method also includes pre-processing the main signal (IP) to extract at least one third frequency component (CF3) corresponding to the natural frequency shared by the first rotating shaft system (HP) and the second rotating shaft system (BP) from the main signal, and generate a filtered main intermediate signal (IPF), wherein the extraction of at least one of the first frequency component (CF1) and the second frequency component (CF2) is achieved by processing the filtered main (IP) intermediate signal (IPF).

5. The method according to claim 4, further comprising generating a third auxiliary signal (CTRL_3) based on the third frequency component (CF3), the third auxiliary signal being used to command the electrical system (4) to draw power from a DC source (431).

6. The method according to claim 1, wherein: The auxiliary power source (BP, 431) is a second rotating shaft system (BP) of the gas turbine engine (2), the method further comprising: processing the primary signal (IP) to extract from the primary signal a second frequency component (CF2) corresponding to a natural frequency of the second rotating shaft system (BP) and generating a filtered second primary signal (IF2) without the second frequency component (CF2); A third auxiliary signal (CTRL_3) is generated based on the first frequency component (CF1) and the second frequency component (CF2), the third auxiliary signal being used to command the electrical system (4) to draw power from a DC source (431).

7. The method according to claim 6 further comprises pre-processing the main signal (IP) based on an instruction (Cons) for distributing power extraction between the first rotating shaft system (HP), the second rotating shaft system (BP) and the DC source (431) to generate a filtered first intermediate signal (IIF1), a filtered second intermediate signal (IIF2) and a filtered third intermediate signal (IIF3), wherein the filtered first intermediate signal is used to command the electrical system (4) to extract mechanical power from the first rotating shaft system (HP), the filtered second intermediate signal is used to command the electrical system (4) to extract mechanical power from the second rotating shaft system (BP), and the filtered third intermediate signal is used to command the electrical system (4) to extract power from the DC source (431), wherein Extracting the first frequency component (CF1) is achieved by processing the filtered first intermediate signal (IIF1), extracting the second frequency component (CF2) is achieved by processing the filtered second intermediate signal (IIF2), and generating a third auxiliary signal (CTRL_3) is achieved based on the filtered third intermediate signal (IIF3).

8. The method according to any one of claims 1 to 7, wherein: Generating one of the first auxiliary signal (CTRL_1) and the second auxiliary signal (CTRL_2) is achieved based on a threshold value (Se1, Se2, Se3) for a maximum authorized extraction from one of the first rotating shaft system (HP) and the auxiliary power source (BP, 431).

9. An electrical system (4) for an electric hybrid gas turbine engine (2), comprising: a power supply bus (40) intended to be connected to at least one load (400) and configured to supply power to the load (400) in the form of a DC signal; a first AC generator (411) intended to be connected to a first rotating shaft (HP) of the gas turbine engine (2) in order to extract mechanical power from the first rotating shaft (HP) and to convert it into electrical power capable of being transmitted to the bus (40); a second AC generator (421) intended to be connected to a second rotating shaft system (BP) of the gas turbine engine (2) in order to extract mechanical power from the second rotating shaft system (BP) and to convert it into electrical power capable of being transmitted to the bus (40); a first converter (410) connecting the first AC generator (411) to the bus (40) and configured to adjust the bus (40) voltage based on the power supplied by the first AC generator (411); a second converter (420) connecting the second AC generator (421) to the bus (40) and configured to adjust the bus (40) voltage based on the power supplied by the second AC generator (421); as well as A control device (412, 422, 432, 4000) connected to the converter and configured to control the converter to compensate for variations in a bus (40) voltage by implementing a method according to any one of claims 1 to 8.

10. A gas turbine engine (2), comprising: The electrical system (4) according to claim 9; a first rotating shaft system (HP) connected to said first generator (411); and A second rotating shaft system (BP) is connected to the second generator (421).

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