Power control unit

Abstract

To provide a power control unit 1 for a ship's propulsion system 100, comprising an internal combustion engine 4 and a shaft 2 having a shaft generator 5. [Solution] The power control unit 1 is configured to provide fuel commands to the internal combustion engine 4 based on the low-speed component of the shaft 2 speed error, i.e., the low-speed component of the deviation of the shaft speed from the speed setpoint. A generator power command is provided to the shaft generator 5 based on the high-speed component of the shaft 2 speed error and the state of the electrical grid of the electrical grid electrically connected to the shaft generator 5. An energy buffer 7 is used to store power from the shaft generator 5, release power to the shaft generator 5, and release power to the electrical grid 8. Thus, it becomes easier to achieve a more stable engine control system and avoid engine overload.

Description

Technical Field

[0001] The present invention relates to a power control unit according to the comprehensive terms of claim 1, a propulsion system having such a power control unit, and a method of controlling such a propulsion system.

Background Art

[0002] The propulsion system preferably comprises an internal combustion engine, such as a large marine or stationary engine with cylinders having an inner diameter of at least 200 mm. The engine is preferably a two-stroke engine or a two-stroke crosshead engine. The engine may be a diesel engine, a gas engine, a dual-fuel engine or a multi-fuel engine. In such an engine, combustion of liquid fuel and / or gaseous fuel, as well as self-ignition or forced ignition, is possible.

[0003] The internal combustion engine may be a two-stroke engine scavenged longitudinally.

[0004] The term internal combustion engine also means a large engine that can be operated not only in diesel mode, characterized by self-ignition of the fuel, but also in Otto mode, characterized by forced ignition of the fuel, or a mixture of these two modes. Furthermore, the term internal combustion engine includes in particular dual-fuel engines and large engines in which self-ignition of the fuel is used for forced ignition of another fuel. Forced ignition can be achieved by using a pre-chamber, a spark plug, and / or pilot fuel.

[0005] The engine speed is preferably less than 800 RPM, particularly for a four-stroke engine, and more preferably less than 200 RPM, indicating a low-speed engine designation, particularly for a two-stroke engine.

[0006] The fuel may be diesel or marine diesel oil, heavy fuel oil, emulsion, slurry, methanol, or ethanol, as well as gases such as liquid natural gas (LNG), liquefied petroleum gas (LPG), natural gas (NG), or petroleum gas (PG).

[0007] Further possible fuels include liquefied biogas (LBG), biological fuels (e.g., oils made from algae or seaweed), ammonia, hydrogen, and synthetic fuels from CO2 (e.g., those produced by power-to-gas or power-to-liquid).

[0008] Large vessels, especially those used for transporting goods, are typically powered by internal combustion engines, particularly diesel and / or gas engines, mainly two-stroke cross-head engines.

[0009] Typically, two-stroke internal combustion engines, such as those used for propulsion in ships, are equipped with shaft generators.

[0010] The shaft generators are used to generate electricity to power various onboard equipment, such as pumps, gas reliquefaction plants, reefer containers, and the overall hotel load.

[0011] Typically, shaft generators are coupled to the AC grid via a variable-frequency drive (VFD). According to DK202270114A1, the shaft generator control system is configured to make power consumption different from power generation within a first period of at least 2 seconds in order to maintain the inherent stabilization of the system.

[0012] It is known that an internal combustion engine can be controlled, particularly by a fuel supply control system, by automatically maintaining a given engine shaft rotation speed through a metered fuel supply.

[0013] However, shaft speed can fluctuate due to changes in external conditions such as weather conditions or sudden changes in electrical load, which can result in rapid fluctuations in fuel supply. This can lead to engine overload and / or system instability. Furthermore, the system's inertia may be excessively high, making it impossible for the engine to respond to such rapidly fluctuating fuel supply commands. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] DK202270114A1 [Overview of the project] [Problems that the invention aims to solve]

[0015] Therefore, an object of the present invention is to provide a power control unit, a propulsion system, and a method for controlling a propulsion system that at least partially avoid the shortcomings of prior art solutions and provide a more stable engine control system and a reduction in the risk of engine overload. [Means for solving the problem]

[0016] According to a first aspect of the present invention, this objective is achieved by a power control unit for a propulsion system comprising an internal combustion engine and a shaft for transmitting thrust from the engine.

[0017] The propulsion system is preferably a marine propulsion system. The internal combustion engine is preferably a large marine engine having at least one cylinder with a bore of at least 200 mm, and is preferably a two-stroke engine and / or a two-stroke cross-head engine.

[0018] The power control unit is configured to provide engine power commands to the internal combustion engine based on the state of the shaft.

[0019] In the present application, the state of the shaft describes the dynamic characteristics of the shaft, such as the rotational speed, rotational frequency, or torque of the shaft, which is given by the speed of the propeller, typically the number of revolutions per minute.

[0020] According to the present invention, the power control unit comprises a discriminator configured to derive high-speed components and low-speed components from the state of the shaft, such as a filter or a discriminator based on FFT.

[0021] In the present application, preferably, shaft state vibrations having any period of 25 seconds or less can be regarded as "high-speed", and shaft state vibrations having any period exceeding 25 seconds can be regarded as "low-speed".

[0022] A time-dependent signal corresponding to the shaft state may be sent through a low-pass filter and / or a high-pass filter in order to obtain low-speed components and / or high-speed components, respectively.

[0023] The low-speed component corresponds to the gently changing part of the shaft state that occurs at a low frequency, and the high-speed component is associated with a higher frequency.

[0024] The low-speed component may depend on adjustable parameters of the internal combustion engine, such as load, amount of fuel, type of fuel, amount of recirculated exhaust gas, or gently varying influencing factors such as ambient temperature, ambient pressure, overall wind direction, or ocean current.

[0025] The high-speed component may be dependent on high-speed changing factors such as ocean waves.

[0026] For the control loop, it may be advantageous to distinguish between high-speed components and low-speed components according to the control variable.

[0027] The discriminator is preferably a frequency discriminator, and the frequency discriminator can separate an axial state portion in a range not exceeding a predetermined second frequency from an axial state portion in a range not exceeding a predetermined first frequency. Therefore, the frequency discriminator is configured to separate a low-speed axial state component in a range not exceeding the first frequency from a high-speed axial state component in a range exceeding the second frequency.

[0028] The predetermined first frequency may be equal to the predetermined second frequency. The discriminator may include a frequency filter implemented by respective software components and may use a fast Fourier transform (FFT).

[0029] The power control unit may be configured to receive and / or store the first predetermined frequency and / or the second predetermined frequency. The first predetermined frequency and / or the second predetermined frequency are preferably, advantageously within a range of a typical sea wave frequency or several times higher than a typical sea wave frequency, specifically within a range from 0.05 Hz to 0.1 Hz.

[0030] The first predetermined frequency and / or the second predetermined frequency may be determined during a shop trial or a sea trial. The frequency may depend on the type of fuel, load, type of engine, and / or type of propeller.

[0031] The internal combustion engine is preferably a dual-fuel engine. The power control unit may be configured to switch between operation with a first fuel such as LNG, LPG, methanol, ethanol, or ammonia and operation with a second fuel such as a diesel-like fuel. During operation with the first fuel, the first predetermined frequency and / or the second predetermined frequency of the first fuel may be set. During operation with the second fuel, the first predetermined frequency and / or the second predetermined frequency of the second fuel may be set. This makes it possible to adapt the discrimination of the low-speed component from the high-speed component based on the type of fuel used.

[0032] Because the combustion period depends on the fuel, engines may be more or less sensitive to changes in load. For example, the combustion period of low-pressure gas is shorter than that of diesel. Therefore, when changes in load occur, diesel operation can be more robust than gas operation.

[0033] Therefore, the first predetermined frequency and / or the second predetermined frequency are generally fuel-dependent. For a dual-fuel engine, the power control unit may be configured to set a first predetermined frequency and / or a second predetermined frequency according to the fuel being used, and to switch between each of the first predetermined frequency and / or the second predetermined frequency, particularly according to the fuel being used. The first predetermined frequency and / or the second predetermined frequency may be determined based on or selected from a table of first predetermined frequencies and / or second predetermined frequencies stored in the memory of the power control unit.

[0034] The power control unit may be part of the engine control system and / or drive control system, and / or may be adapted to receive inputs from other parts of the combustion engine and to take these inputs into account in order to provide engine power commands.

[0035] The power control unit is preferably configured to receive shaft state data indicating the state of the shaft.

[0036] The shaft condition data may indicate the shaft speed and / or shaft torque.

[0037] The shaft condition data may be represented by a first sensor signal provided by a first sensor. The sensor may be a speed sensor, such as a rotational speed counter, or a torque sensor positioned to measure the speed and / or torque of the shaft.

[0038] Generally, torque fluctuations affect the rotational speed of the shaft. The shaft speed may be used as a reference signal.

[0039] Since the method for measuring shaft speed is extremely accurate while the method for measuring torque is not very accurate, using torque fluctuation rate is less preferable. In particular, shaft speed can be measured with extreme precision.

[0040] The engine power command may include a fuel command for an internal combustion engine.

[0041] The fuel directive may specify the amount of fuel to be injected into the engine, for example, via a fuel supply system, such as diesel, heavy fuel oil, LNG, methanol, or ammonia.

[0042] Fuel commands are typically provided according to the shaft speed, shaft torque, and / or shaft speed setpoint, which are stored in and / or received by the power control unit.

[0043] If the actual shaft speed differs from the shaft speed setpoint, the amount of fuel may be increased or decreased depending on whether the speed is excessively high or excessively low. Frequent changes in shaft speed may destabilize the control loop.

[0044] According to the present invention, a fuel command is preferably provided in accordance with the slow component, while the high-speed component is not considered. This is meant by the term "solely based on the slow component" (see below).

[0045] Alternatively or additionally, the engine power commands may include commands for setting the variable compression ratio, exhaust recirculation rate, and / or ignition timing.

[0046] Preferably, engine power commands, in particular fuel commands, are provided in accordance with the low-speed component of the shaft state, and in particular, engine power commands are based solely on the low-speed component of the shaft state. In this context, "based solely on the low-speed component" means that the fuel command is not based on the high-speed component.

[0047] Engine power commands, particularly fuel commands, may be provided according to the low-speed component, and the frequency is below a first predetermined limit value.

[0048] Providing engine power commands in response to low-speed components may establish a control loop for providing a more stable and / or at least more gradually fluctuating fuel supply.

[0049] When high-speed components of shaft speed are considered in order to provide fuel commands related to frequencies above a predetermined frequency, there is a risk that the fuel commands will exceed the maximum permissible load, at least for a short period of time, and this risk shall be avoided.

[0050] Therefore, distinguishing between high-speed and low-speed components can help keep the engine running within its operating limits and / or in a more favorable configuration in terms of fuel efficiency, exhaust emission values, engine wear, etc. This can help improve both the economic and environmental efficiency of the engine.

[0051] Considering only the low-speed component of shaft conditions, such as shaft speed, when providing fuel commands can potentially reduce fuel consumption because it avoids excessive fuel peaks due to transient effects.

[0052] Additionally, a decrease in lambda (air-fuel ratio) may be avoided.

[0053] By reacting only with low-speed components, fuel can be saved.

[0054] The first and second frequencies may depend on the fuel type and compression ratio.

[0055] The power control unit may be configured to set a first predetermined frequency and / or a second predetermined frequency in accordance with the compression ratio, particularly the geometric compression ratio of a VCR engine. The first predetermined frequency and / or the second predetermined frequency may be selected from a stored table of predetermined first predetermined frequencies and / or second predetermined frequencies.

[0056] For example, in an engine with a VCR that has a low compression ratio, speed vibrations may have a smaller impact on fuel consumption. Therefore, the discrimination does not need to react to small power fluctuations and overloads.

[0057] However, when high compression ratios are used, discrimination requires tuning for a faster response.

[0058] Small overload margins can be compensated for by batteries that act as buffers and provide additional margins. The optimal compression ratio can be more easily maintained, and if additional power is needed for propulsion, batteries can be used to temporarily supplement the power requirements (see below).

[0059] The propulsion system may further include a shaft generator connected to the shaft to receive and / or supply mechanical power to the shaft.

[0060] For these propulsion systems, the power control unit may be configured to provide a generator power command to the shaft generator indicating the mechanical power to be received from and / or supplied to the shaft by the shaft generator. Thus, the extraction and / or supply of mechanical power can be controlled by the power control unit.

[0061] The generator power command may be based on the high-speed component of the shaft state, and in particular, on only the high-speed component of the shaft state. In this context, "based only on the high-speed component" means "independent of the low-speed component."

[0062] Therefore, shaft generators can respond more immediately to control commands. Consequently, shaft generators are less prone to instability when rapid changes occur. Furthermore, since shaft generators are typically electrically driven, power can be delivered almost instantaneously.

[0063] The generator power command may be provided according to the high-speed component, and the frequency may exceed a second predetermined limit.

[0064] The second predetermined limit value may be the same as the first predetermined limit value, or it may be different.

[0065] Generally, the external torque applied to the shaft may be propulsion torque, rudder motion, or variable propeller torque caused by ocean wave loads, and shaft generator torque related to variable electrical loads.

[0066] Generator power commands that cause fluctuations in the electrical load in response to high-speed components may affect the shaft condition, particularly the high-speed components, and may provide a basis for a closed control loop that results in a more stable high-speed component and / or minimized high-speed vibrations.

[0067] The generator power command may be based on the high-speed component of the shaft speed. In general, the shaft generator electrical load can be directly controlled by torque, especially the high-speed component.

[0068] The power control unit may be configured to receive electrical grid status data, such as power requirements, of the electrical grid electrically connected to the shaft generator. The power control unit is configured to provide generator power commands and / or engine power commands in response to the received electrical status data.

[0069] The electrical grid conditions may include data relating to the voltage, current, electrical load, electrical frequency, and power of the electrical grid or one or more parts thereof.

[0070] The electric grid may include an electric consumer and / or additional generators driven by, for example, an auxiliary engine.

[0071] In particular, the electric grid may include an electric buffer. The generator power command may relate to the power requirements of the electricity consumer and / or the power requirements or capacity of the electric buffer.

[0072] The generator power command may be provided according to the high-speed component, and the frequency may exceed a second predetermined limit. The high-speed component may be a fluctuating signal. An electrical buffer may stabilize the electrical grid by compensating for the fluctuating energy supply.

[0073] In addition to the shaft conditions, the electrical grid conditions may also be considered when providing generator power commands and / or engine power commands. In particular, when the electrical grid requires more energy, the engines may be provided with their respective fuel commands.

[0074] While the shaft generator electrical load can generally be controlled by the high-speed component of torque or shaft speed, there may be cases where it is necessary to provide additional energy to the electrical grid, particularly the electrical buffer, for example, slowly fluctuating power requirements. In this case, the generator power command may also be based on the low-speed component. Subsequently, a portion of the power from the shaft may be used to provide electrical energy. As a result, separate fuel commands may arise to supply additional electrical energy.

[0075] The shaft generator power command may set an appropriate electrical load to correspond to the required electricity consumption of the ship's electrical grid.

[0076] The shaft generator power command may set an appropriate electrical load that is buffered by an electrical energy storage device.

[0077] If necessary, the power control unit may provide fuel commands in accordance with electrical state data to generate more energy, for example, to the shaft generator and the electrical grid.

[0078] The electrical grid may be equipped with a regulator or electrical load control device, which controls the electrical grid in particular according to the state of the electrical grid.

[0079] Data indicating the state of the electrical grid may also be provided to the electrical grid regulator.

[0080] The regulator may provide data to the power control unit, or through the power control unit, it may provide engine control commands if, for example, more electrical energy is needed for the electric grid than is provided by the shaft, or generator power commands if, for example, more mechanical power is needed due to a high-speed component of the shaft condition.

[0081] The power control unit may be configured to provide engine power commands and / or generator power commands based on deviations of the shaft state from a set point, particularly deviations of shaft speed from a speed set point and / or deviations of shaft torque from a torque set point. The set points may be stored in the power control unit and / or received by the power control unit.

[0082] The speed setting point is a predetermined number of revolutions per minute on the propeller curve, corresponding to the torque or load, for determining the corresponding amount of fuel required.

[0083] The power control unit may be configured to provide engine power commands and / or generator power commands based on deviations of the high-speed and / or low-speed components of the shaft state from their respective set points.

[0084] The setting point may depend on the specific engine layout, the intended ship speed, and the intended acceleration profile.

[0085] The relationship between deviations and their respective fuel commands and / or generator power commands may be predetermined and stored and / or received by the engine power control unit.

[0086] The setpoints and acceptable deviations may be determined by factory testing or provided to the ship via a remote configuration, such as a satellite data link.

[0087] The power control unit may be configured to continuously provide engine power commands and / or generator power commands throughout the entire engine operating range, not only during the engine start-up phase, fuel change operations, and / or intended load change operations. This helps in terms of efficiency and fuel consumption, relieves stress on components, and reduces vibration.

[0088] According to a second aspect of the present invention, the object of the present invention is also achieved by a propulsion system comprising a power control unit according to the first aspect of the present invention.

[0089] The propulsion system is particularly a propulsion system for ships.

[0090] The propulsion system includes a power control unit as described above. The propulsion system further includes an internal combustion engine having at least one cylinder with an inner diameter of at least 200 mm, preferably a two-stroke engine and / or a two-stroke cross-head engine. The internal combustion engine is preferably a dual-fuel engine.

[0091] The propulsion system comprises a shaft for transmitting thrust from the engine. The propulsion system further comprises a first sensor for providing a power control unit with shaft state data indicating the state of the shaft, particularly the shaft speed and / or shaft torque.

[0092] The power control unit is configured to provide engine power commands to the internal combustion engine, and these engine power commands are based particularly on the low-speed component of the shaft state.

[0093] The propulsion system may further include a shaft generator connected to the shaft to receive and / or supply mechanical power to the shaft.

[0094] The power control unit may be configured to provide a generator power command to the shaft generator indicating the mechanical power to be received from and / or supplied to the shaft by the shaft generator, the generator power command being based in particular on the high-speed component of the shaft state.

[0095] The power control unit may be separated into an engine control unit and an electrical control unit, or it may be a single integrated control unit. The power control unit may also be part of the overall engine control unit.

[0096] The propulsion system may further include a second sensor for providing a power control unit with electrical state data indicating the state of the electrical grid of the electrical grid electrically connected to the shaft generator.

[0097] Generator power commands and / or engine power commands may be based on electrical status data, such as the demand for electrical energy by onboard electricity consumers.

[0098] The propulsion system may further include an energy buffer, such as a battery, electrically connected to the shaft generator and / or the electric grid, the energy buffer being configured to store and release electrical energy. Thus, power can be received from the shaft and stored in the energy buffer, and / or taken out of the energy buffer and supplied to the shaft or an electrical consumer.

[0099] The electrical state data may include buffer data indicating the state of the energy buffer, such as the charge level, so that the power control unit may take buffer data into consideration when providing generator power commands and / or engine power commands.

[0100] The generator power command may result in the extraction of generator power from the shaft and its transmission to the electrical grid, and / or being buffered in an energy buffer, and / or the provision of electrical energy from the energy buffer and its conversion into mechanical energy to be supplied to the shaft. Thus, it becomes easier to meet power requirements, which can help stabilize the system.

[0101] The propulsion system's electrical grid may be equipped with a regulator or electrical load control device, which may be adapted to distribute power to the consuming elements, energy buffers, and shafts. The regulator may be adapted to provide instructions for handling the grid and / or energy buffers, depending on the onboard power consumption needs and the power input or power output requirements of the shafts.

[0102] During normal operation, the average power supplied by the shaft generator should be equal to the power required by the grid. Transient events may be covered by an energy buffer.

[0103] The energy buffer may be any battery, preferably a high-power battery such as a lithium-nickel-cobalt-manganese oxide (NMC) or lithium titanate or lithium titanium oxide (LTO) battery.

[0104] The output capacity of the energy buffer may be within at least 1% of the maximum internal combustion engine output. Repeated short charge / discharge cycles should have only a minimal impact on the life cycle. As stated, NMC and LTO are effective solutions. Lithium iron phosphate (LFP) batteries can also be used, but since the discharge / charge current of such batteries is lower, higher capacity batteries may be used.

[0105] The propulsion system may include a power control unit, which may be configured to provide generator power commands and / or engine power commands based on deviations of the shaft state from a set point, particularly deviations of the shaft state from the high-speed and / or low-speed components of the shaft state.

[0106] The propulsion system may advantageously include a frequency discriminator configured to separate low-speed shaft state components in a range below a predetermined first frequency from high-speed shaft state components in a range above a predetermined second frequency.

[0107] Advantageously, the internal combustion engine may be a dual-fuel engine, and the frequency discriminator may be configured to set a first frequency and / or a second frequency depending on the fuel being used. This makes it easier to adapt to different fuels, as described above.

[0108] In another preferred embodiment, the propulsion system may include a wind-driven component such as a Flettner rotor. A Flettner rotor is a vertical cylinder mounted on the ship that rotates and generates a driving force due to the so-called Magnus effect. The wind-driven component may be mechanically or electrically driven to generate the driving force. The driving force may be generated by an electric grid and / or by a shaft generator driven by an engine as described above. The wind-driven component, such as a Flettner rotor, may reduce the ship's fuel consumption.

[0109] In a propulsion system equipped with such wind-driven components, the ship's propulsion is typically provided by both propeller-driven operation, i.e., operation using the ship's propeller coupled to a shaft, and the thrust provided by the wind-driven components.

[0110] The propulsion system control unit may switch the ratio between propeller-driven operation and wind-assisted operation. When the propeller-driven system is operating solely on propeller power and the wind-driven element is set to passive mode, the power control unit may operate as described above.

[0111] During (partial) wind-assisted operation, when the wind-driven elements are set to the active state, the shaft may experience additional transient components, such as those caused by changes in wind, in addition to transient components caused by ocean waves, currents, etc. Such sudden changes in wind direction and / or wind speed may affect the shaft torque and / or speed. Sudden changes in driving force caused by sudden changes in wind may result in sudden changes in engine load, which could lead to unexpected engine shutdown. This should be prevented.

[0112] Therefore, the power control unit may be configured to set a first frequency and / or a second frequency in accordance with the propeller drive operation and parameters related to the wind drive components, such as wind speed, wind direction, and / or the mechanical driving force of the wind drive element.

[0113] The power control unit may switch between propeller-driven operation and wind-assisted operation. For each case, an appropriate first frequency and / or second frequency may be determined and / or set.

[0114] According to a third aspect of the present invention, the objective can also be achieved by a method for controlling a ship's propulsion system, as described above with respect to a second aspect of the present invention.

[0115] The propulsion system comprises an internal combustion engine having at least one cylinder with an inner diameter of at least 200 mm, preferably a two-stroke engine and / or a two-stroke cross-head engine. The engine is preferably a dual-fuel engine.

[0116] The propulsion system further includes a shaft for transmitting thrust from the engine. This method includes the following steps:

[0117] Axis state data indicating the state of the shaft, particularly the shaft speed and / or shaft torque, is provided. The shaft data may preferably be derived from the signal of the first sensor, as described above, and may preferably be received by the power control unit of the propulsion system, as described above.

[0118] The high-speed and low-speed components are derived from the state of the shaft.

[0119] The high-speed and low-speed components are derived by a discriminator having software and / or hardware components.

[0120] The electronic signal of the first sensor may be filtered by an electronic high-pass filter and / or an electronic low-pass filter, and / or the electronic sensor signal may be digitized and filtered by software, for example, based on FFT analysis.

[0121] Subsequently, based on the shaft condition, particularly the low-speed component of the shaft condition, an engine power command, preferably a fuel command, is provided to the internal combustion engine.

[0122] Controlling a combustion engine based on the low-speed component of the shaft state helps keep the system within its operating limits.

[0123] The propulsion system may further include a shaft generator connected to the shaft to receive and / or supply mechanical power to the shaft. When receiving mechanical power from the shaft and generating electrical energy from that mechanical power, the shaft generator acts as a “generator.” When receiving electrical energy and supplying mechanical power to the shaft, the shaft generator acts as an electric motor. Both functions are included by the term “shaft generator” as used herein. The method may include the step of providing a generator power command to the shaft generator indicating the mechanical power to be received from and / or supplied to the shaft, in particular based on the high-speed component of the shaft state.

[0124] The low-speed component may be used for the control loop of the internal combustion engine operation, while the high-speed component of the shaft condition may be compensated by the electric grid. Overall, this leads to more stable shaft conditions and engine operation.

[0125] Electrical state data indicating the state of the electrical grid electrically connected to the shaft generator may be provided, for example, by an electrical grid regulator. In this case, the generator power command and / or engine power command may be based on the state of the electrical grid.

[0126] The state of the electrical grid may be characterized by the power consumption of the external electrical grid, and / or the energy buffer's capacity to take in and / or deliver energy.

[0127] In a further step, power from the shaft may be stored in an energy buffer by the shaft generator, particularly depending on the high-speed component of the shaft state and preferably depending on the state of the electrical grid of the electrical grid electrically connected to the shaft generator.

[0128] Additionally or alternatively, depending on the high-speed component of the shaft state and preferably the electrical grid state of an electrical grid electrically connected to the shaft generator, power from an energy buffer may be supplied to the shaft by the shaft generator.

[0129] If the high-speed component causes the shaft generator output to exceed the ship's electricity demand, additional power may be supplied to the energy buffer.

[0130] If the high-speed component causes the shaft generator output to be lower than the grid's electricity demand, the energy buffer may supply the missing load.

[0131] If the shaft speed decreases or the torque requirement increases, the shaft generator output should be reduced so that the energy needed for the ship's propulsion is not released from the shaft. As an alternative, or in addition, power can be supplied to the shaft by a shaft generator that operates as an electric motor.

[0132] Subsequently, the energy output provided by the energy buffer can be increased so that the energy storage device can provide the necessary power.

[0133] If the shaft speed increases or the torque decreases, the shaft generator output may be increased, and the energy storage device may capture the excess output.

[0134] Setpoints, particularly speed setpoints and / or torque setpoints, may be provided with respect to the state of the shaft.

[0135] Engine power commands and / or generator power commands may be provided based on deviations of the shaft state from a set point, particularly deviations of the shaft velocity from a speed set point. This makes it easier to keep the propulsion system within its ideal operating limits.

[0136] The internal combustion engine may be a dual-fuel engine, and the method may include the step of separating the low-speed shaft state component, which is in a range below a predetermined first frequency, from the high-speed shaft state component, which is in a range above a predetermined second frequency, using a frequency discriminator. The first frequency and / or the second frequency may depend on the fuel used.

[0137] An internal combustion engine may be equipped with a wind-powered drive component.

[0138] This method, - Fuel used, - The ratio of driving force generated by the wind-driven components, - Parameters related to wind-driven components, such as wind direction and / or wind speed. The procedure may include the step of setting and / or determining a first frequency and / or a second frequency, depending on at least one of the following.

[0139] According to another aspect of the present invention, the objective can also be achieved by a vessel equipped with the above-described propulsion system and preferably an electric grid.

[0140] According to yet another aspect of the present invention, the objective is also achieved by a computer program product that includes instructions for causing a power control unit, such as those described above in relation to the first aspect of the present invention, or a propulsion system, such as those described above in relation to the second aspect of the present invention, to perform steps of the method as described above in relation to the third aspect of the present invention.

[0141] The computer program product may be stored on a computer-readable medium.

[0142] Further advantageous aspects of the present invention are described below with reference to exemplary embodiments and drawings. Functionally equivalent elements are given the same reference numerals. [Brief explanation of the drawing]

[0143] [Figure 1] This is a schematic diagram of a propulsion system using advanced technology. [Figure 2] This is a schematic diagram relating to the propulsion system according to the present invention. [Figure 3] This is a schematic diagram showing the changes in the axis velocity setting point over time. [Figure 4a] This is a schematic diagram illustrating an example of the change in axial velocity error over time. [Figure 4b] Figure 4a is a schematic diagram illustrating the typical progression of fuel commands using advanced technology, resulting from shaft velocity errors as shown. [Figure 5a] This is a schematic diagram illustrating an example of the change in axial velocity error over time. [Figure 5b] This is a schematic diagram illustrating an exemplary transition of the fuel command according to the present invention, resulting from the shaft velocity error shown in Figure 5a. [Modes for carrying out the invention]

[0144] Figure 1 shows a schematic diagram of the advanced propulsion system 100.

[0145] The propulsion system 100 comprises an internal combustion engine 4 and a shaft 2 for transmitting thrust from the engine 4.

[0146] The power control unit 1 is configured to provide engine power commands to the internal combustion engine 4 based on the state of the shaft 2. For example, the shaft speed is measured, and if the measured speed is outside the tolerance range for a predetermined shaft speed, more or less fuel is injected into the internal combustion engine 4, depending on whether the speed is excessively low or excessively high.

[0147] In addition, the shaft generator 5 is connected to the shaft 2 to receive mechanical power from the shaft 2 and to supply electricity to the electric grid 8. This allows a portion of the shaft's energy to be diverted to supply power to the electric grid 8.

[0148] The electrical grid 8 may include a consumer (not shown clearly) and an energy buffer 7, which is in particular a battery.

[0149] The electric grid 8 includes a regulator 6 that distributes the power provided by the shaft generator 5 to the consumer and the battery 7 according to the state of the electric grid 8. For example, if the consumer does not require any energy, the battery may be charged. If the consumer requires more energy than is provided by the shaft generator 5, energy may be drawn from the battery 7.

[0150] According to advanced technology, fuel control and electricity grid control are independent of each other.

[0151] Figure 2 shows a schematic diagram of the propulsion system 100 according to the present invention.

[0152] The propulsion system 100 comprises an internal combustion engine 4 and a shaft 2 for transmitting thrust from the engine 4. The power control unit 1 is configured to provide engine power commands, including fuel commands, to the internal combustion engine 4 based on the state of the shaft 2, specifically the low-speed component of the shaft speed error (i.e., deviation from the speed setpoint).

[0153] According to the present invention, the power control unit 1 includes a discriminator 3 configured to derive high-speed and low-speed components from the state of the shaft 2. Only the low-speed component of the shaft state is used to determine the fuel command.

[0154] The shaft generator 5 is connected to shaft 2 to receive mechanical power from shaft 2 and supply electricity to the electric grid 8, and, if necessary, to receive electricity from the electric grid 8 and supply mechanical power to shaft 2.

[0155] Therefore, the shaft generator 5 can be considered a bidirectional interface between the shaft 2 and the electrical grid 8.

[0156] The electrical grid 8 comprises a consumer (not shown) and a battery that acts as an energy buffer 7.

[0157] The electric grid 8 is equipped with a regulator 6, which, on the one hand, distributes the power supplied by the shaft generator 5 to the consumers and batteries 7 according to the state of the electric grid 8.

[0158] On the other hand, the regulator 6 is connected to the power control unit 1 to receive generator power commands.

[0159] Depending on the state of the electric grid 8 and the generator power command, if the electrical energy provided by the shaft generator 5 is insufficient for the electric grid 8, the regulator 6 may provide a fuel command to the control unit 1 to increase engine output.

[0160] The power control unit 1 is configured to provide a generator power command to the shaft generator 5, which indicates the mechanical power that should be received from and / or supplied to the shaft 2 by the shaft generator 5.

[0161] The generator power command is based solely on the high-speed component of the state of shaft 5.

[0162] Therefore, rapid changes in shaft speed may be responded not by changes in the amount of fuel injected into engine 4, but by changes in the mechanical energy absorbed or supplied by shaft generator 5.

[0163] The propulsion system 100 includes a first sensor 11, specifically an axis speed sensor that provides axis state data to the control unit 1.

[0164] The electrical grid 8 includes a second sensor 10 for providing electrical state data to the regulator 6.

[0165] Figure 3 shows an example of the changes in the axis velocity setting point (straight line) and axis velocity (vibration line) over time.

[0166] The intended shaft speed is initially increased, then kept constant, and may be further increased at a gentler gradient thereafter.

[0167] Figure 4a shows an illustrative trend of axial velocity error using advanced technology.

[0168] In this case, the axial velocity error has a high-speed fluctuating component of oscillation, for example, due to ocean waves.

[0169] The fuel command typically attempts to follow this behavior, as shown in Figure 4b. However, due to system inertia, the system may not be able to follow along.

[0170] Figure 4b shows an exemplary progression of fuel commands using advanced technology, resulting from shaft velocity errors as shown in Figure 4a. As a result of rapidly fluctuating shaft velocity errors, fuel commands may oscillate and exceed the system's load limits.

[0171] Vibrations in fuel commands can even amplify shaft velocity vibrations, potentially worsening the situation.

[0172] Figure 5a shows an exemplary change in the axial velocity error over time for the propulsion device according to the present invention.

[0173] In this figure, the curve labeled ControlError exhibits high-speed oscillations and relates to the shaft velocity error, while the curve labeled ControlErrorPS is smoother and relates only to the low-speed component of the shaft velocity error.

[0174] Furthermore, as can be seen in the control error curve with high-speed oscillations in this example, the shaft velocity error fluctuates rapidly due to ocean waves.

[0175] However, since the fuel command to engine 4 (see Figure 2) does not respond to the high-speed component of the shaft speed error, but only to the low-speed component of the shaft speed error (i.e., the control error PS curve), the system can be controlled much more smoothly, as can be seen in Figure 5b.

[0176] Figure 5b shows an exemplary transition of the fuel command according to the present invention, resulting from the low-speed component of the shaft speed error (i.e., the control error PS curve) as shown in Figure 5a.

[0177] Because only the low-speed component of the shaft speed is considered when setting the fuel command, the fuel command does not oscillate at high speeds and does not oscillate in smaller ranges. This helps to maintain the majority of the fuel command within limits such as those represented by the upper and lower bandwidth lines.

[0178] The frequency limit for distinguishing between high-speed and low-speed components is preferably set such that fuel consumption is minimized over time along the shaft speed setpoint.

Claims

1. A power control unit (1) for a propulsion system (100), wherein the propulsion system (100) comprises an internal combustion engine (4), particularly a dual-fuel two-stroke engine, having at least one cylinder with an inner diameter of at least 200 mm, and a shaft (2) that transmits thrust from the internal combustion engine (4), The power control unit (1) is configured to provide engine power commands to the internal combustion engine (4) based on the state of the shaft (2). The power control unit (1) includes a discriminator (3) configured to derive high-speed and low-speed components from the state of the shaft (2). Power control unit (1).

2. The power control unit (1) according to claim 1, wherein the discriminator is a frequency discriminator configured to separate a low-speed shaft state component in a range below a predetermined first frequency from a high-speed shaft state component in a range above a predetermined second frequency.

3. The power control unit (1) according to claim 1 or 2, configured to receive shaft state data indicating the state of the shaft (2), and in particular the shaft state data indicating the speed and / or torque of the shaft (2).

4. The power control unit (1) according to any one of claims 1 to 3, wherein the engine power command includes a fuel command for the internal combustion engine (4).

5. The power control unit (1) according to any one of claims 1 to 4, configured to provide the engine power command based on the low-speed component of the state of the shaft (2), and in particular the engine power command is based solely on the low-speed component of the state of the shaft (2).

6. The propulsion system (100) further comprises a shaft generator (5) connected to the shaft (2) for receiving mechanical power from the shaft (2) and / or supplying mechanical power to the shaft (2), The power control unit (1) is - It is configured to provide a generator power command to the shaft generator (5) indicating the mechanical power to be received from and / or supplied to the shaft (2) by the shaft generator (5), In particular, the power control unit (1) according to any one of claims 1 to 5, wherein the generator power command is based on the high-speed component of the state of the shaft (2), and in particular only on the high-speed component of the state of the shaft (5).

7. The power control unit (1) is configured to receive electrical state data indicating the electrical grid state of the electrical grid electrically connected to the shaft generator (5), The power control unit (1) according to claim 6, wherein the power control unit (1) is configured to provide the generator power command and / or the engine power command based on the received electrical state data.

8. A power control unit (1) according to any one of claims 1 to 7, configured to provide the engine power command and / or the generator power command based on a deviation of the state of the shaft (2) from a set point, in particular a deviation of the speed of the shaft (2) from a speed set point.

9. A power control unit (1) according to any one of claims 2 to 8, configured for a propulsion system (100) having a dual-fuel engine, and configured to set a first frequency and / or a second frequency in accordance with the fuel being used.

10. In particular, a propulsion system (100) for a ship, comprising a power control unit (1) according to any one of claims 1 to 9, - Preferably a dual-fuel two-stroke engine, an internal combustion engine (4) having at least one cylinder with an inner diameter of at least 200 mm, - A shaft (2) for transmitting thrust from the engine (4), - A first sensor (11) for providing the power control unit (1) with shaft state data indicating the state of the shaft, particularly the speed of the shaft (2) and / or the torque of the shaft (2), Furthermore, The power control unit (1) includes a discriminator (3) configured to derive high-speed and low-speed components from the state of the shaft (2), The power control unit (1) is configured to provide engine power commands to the internal combustion engine (4) based on the state of the shaft (2). The engine power command is based in particular on the low-speed component of the shaft (2) in the aforementioned state. Propulsion system (100).

11. - Further comprising a shaft generator (5) connected to the shaft (2) for receiving and / or supplying mechanical power to the shaft (2), The power control unit (1) is configured to provide a generator power command to the shaft generator (5) indicating the mechanical power to be received from and / or supplied to the shaft (2) by the shaft generator (5), The propulsion system (100) according to claim 10, wherein the generator power command is based in particular on the high-speed component of the state of the shaft (2).

12. The system further includes a second sensor (10) for providing the power control unit (1) with electrical state data indicating the electrical grid state of an electrical grid (8) electrically connected to the shaft generator (5), The propulsion system (100) according to claim 11, wherein the generator power command and / or the engine power command are based on the electrical state data.

13. The system further comprises an energy buffer (7) which is electrically connected to the shaft generator (5) and / or the electrical grid (8) and configured to store and release electrical energy, The propulsion system (100) according to claim 12, wherein the electrical state data includes buffer data indicating the state of the energy buffer (7), and the power control unit (1) is configured to take the buffer data into consideration in order to provide the generator power command and / or the engine power command.

14. The propulsion system (100) according to any one of claims 10 to 13, wherein the power control unit (1) is configured to provide the generator power command and / or the engine power command based on the deviation of the state of the shaft (2) from a set point, in particular the deviation of the speed of the shaft (2) from a speed set point and / or the deviation of the torque of the shaft (2) from a torque set point.

15. The propulsion system (100) according to any one of claims 10 to 14, wherein the discriminator is a frequency discriminator configured to separate a low-speed shaft state component in a range below a predetermined first frequency from a high-speed shaft state component in a range above a predetermined second frequency.

16. The propulsion system (100) according to claim 15, wherein the internal combustion engine (4) is a dual-fuel engine, and the frequency discriminator is configured to set a first frequency and / or a second frequency according to the fuel being used.

17. The propulsion system (100) according to claim 15 or 16, further comprising a wind-driven component, in particular a Fretner rotor, wherein the frequency discriminator is configured to set the first frequency and / or the second frequency according to parameters relating to the wind-driven component.

18. A method for controlling a propulsion system (100) according to any one of claims 10 to 17, comprising an internal combustion engine (4), preferably a dual-fuel two-stroke engine, having at least one cylinder having an inner diameter of at least 200 mm, and a shaft (2) for transmitting thrust from the engine (4), wherein the method is - A step of providing shaft state data indicating the state of the shaft, particularly the speed and / or torque of the shaft (2), - A step of deriving the high-speed component and the low-speed component from the state of the shaft (2), - A step of providing an engine power command, preferably a fuel command, to the internal combustion engine (4) based on the state of the shaft (2), particularly the low-speed component of the state of the shaft (2), Methods that include...

19. The internal combustion engine (4) is a dual-fuel engine, and the method is The method according to claim 18, comprising the step of separating low-speed shaft state components in a range of a predetermined first frequency or less from high-speed shaft state components in a range of a range of a predetermined second frequency using a frequency discriminator, wherein the first frequency and / or the second frequency depend on the fuel used.

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