CN117216878B - Ship power system-oriented rapid modeling method and device based on lumped parameter method - Google Patents
Ship power system-oriented rapid modeling method and device based on lumped parameter method Download PDFInfo
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Abstract
The invention discloses a method and a device for modeling a ship power system based on a lumped parameter method, which are suitable for various types of ship power systems, including ships of different types and scales, and can be used for modeling power devices of different types and propulsion devices. The lumped parameter modeling process is simplified and faster than the detailed physical model-based modeling approach, and by using parameterized models and simplified mathematical expressions, a system model can be built and solved faster. The method is suitable for a real-time application scene and can be used for a real-time simulation and control system. By using a simplified model and efficient solution algorithm, it is possible to run and respond in a real-time environment. By establishing transfer relationships and energy balance equations between components, interactions and energy transfer between the various components can be accurately described.
Description
Technical Field
The invention belongs to the technical field of system modeling, and particularly relates to a rapid modeling method and device for a ship power system based on a lumped parameter method.
Background
Marine power systems typically include simulations of pipe network systems and simulations of equipment in marine power systems. At present, a node pressure method is mainly adopted to solve a pipe network system, the method focuses on macroscopic parameters such as pressure, temperature, specific enthalpy value, flow and the like in the pipe network system, and the calculated amount is reduced by neglecting some complex internal changes. The simulation of the equipment module mainly adopts a coupling method of a pipe network system and an equipment model, determines coupling parameters of the pipe network system and the equipment module, and correspondingly simplifies the equipment model aiming at the coupling parameters, thereby establishing the equipment model in the ship power system.
However, because the parameters of the pipe network system and the equipment are different, the modeling method and the solving method of the pipe network system and the equipment are not completely consistent, and when data exchange is performed, stability influences of different degrees can be generated on solving calculation for different exchange data. In addition, the simulation of the system generally needs to reach real time or even super real time, the refinement degree of the current simulation technology is not high enough, and the traditional ship power system modeling method needs to consider a large number of complex coupling relations, so that the modeling process is slow, the calculation complexity is high and the real-time performance is not enough.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a rapid modeling method for a ship power system based on a lumped parameter method, which comprises the following steps:
s1, determining a system boundary and equipment components of a ship power system, and determining equipment components to be modeled based on the coupling relation and the signal transmission path between the equipment components based on the characteristics and the functions of the ship power system, wherein the equipment components comprise a host device, a propulsion device and a transmission device;
s2, defining parameters and initial conditions of each equipment component, wherein the parameters comprise input signals and output signals, the input signals comprise control signals, environment conditions or output signals of other equipment components, the output signals comprise rotating speed, thrust force and torque, and the initial conditions comprise initial states, initial values and initial inputs of each equipment component;
s3, establishing a device component model, and selecting a model equation to model each device component based on the parameter characteristics of each device component;
s4, establishing an overall system model, and constructing an overall ship power system model according to the coupling relation among the equipment components and the input and output signal transmission paths of the equipment components;
and S5, solving an integral system equation by using an Euler method, verifying the ship power system model, and adjusting and correcting according to a verification result.
Wherein, establishing the equipment component model comprises host device modeling, propulsion device modeling and transmission device modeling;
the host device modeling includes using a transfer function model to represent the power output of the engine, using a first order inertia model to represent the acceleration response of the engine, and building an engine model:
T_engine(s)＝K_engine/(Ts+1)
wherein T_Engine(s) is the transfer function of the engine, K_Engine is the gain parameter, and T is the time constant;
using the relation between the mass and the force to represent the change of the acceleration of the ship, and building a kinetic model of the acceleration of the ship according to the force output by the engine and the mass of the ship:
a_ship＝F_engine/m_ship
where a_ship is the acceleration of the ship, f_engine is the force output by the engine, and m_ship is the mass of the ship.
The propulsion device modeling comprises the steps of representing the propulsion characteristics of the propeller by using a transfer function model, representing the propulsion response of the propeller by using a second-order inertia model, and establishing a propeller model:
T_propeller(s)＝(K_propeller*ω_n^2)/(s^2+2ξω_n s+ω_n^2)
wherein, T_propeller(s) is the transmission function of the propeller, K_propeller is the gain parameter, omega_n is the natural frequency, and xi is the damping ratio;
according to the propulsion characteristics of the propeller and the motion state of the ship, a dynamic model of the propulsion is established, and the following relationship exists between the transmission function of the propulsion and the propeller and the speed of the ship:
F_propulsion＝T_propeller*ω_propeller*r_propeller-F_resistance
wherein F_propulsion is propulsion, T_propeller is a transmission function of a propeller, omega_propeller is the rotating speed of the propeller, r_propeller is the radius of the propeller, and F_resistance is the resistance of the ship.
The modeling of the transmission device comprises the steps of representing the transfer characteristic of the transmission device by using a transfer function model, representing the response of the transmission device by using a first-order inertia model, and establishing a transmission device model:
T_transmission(s)＝K_transmission/(Ts+1)
where t_ transmission(s) is the transmission function of the transmission, k_transmission is the gain parameter, and T is the time constant;
according to the output of the transmission device and the input of the propeller, a transmission relation between the axis and the propeller is established, the output of the transmission device is directly connected to the input of the propeller, and an axis and a propeller model is established:
ω_propeller＝T_transmission*ω_engine
where ω_propeller is the rotational speed of the propeller, t_transmission is the transmission function of the transmission, and ω_engine is the rotational speed of the engine.
Wherein, the establishing of the whole system model comprises the following steps:
based on the dynamic balance equation, an integral ship dynamic system equation is constructed according to the coupling relation of all equipment components and the inertia, resistance, external excitation, propulsion and load factors of a ship system, and the integral dynamic balance equation of the ship dynamic system can be expressed as:
M_sys*dV/dt+(C_sys+C_prop)*V+(D_sys+D_prop)*V^2+G_sys＝T_prop-T_res-T_load
where V is the vessel speed, M_sys is the vessel total inertial mass, C_sys is the vessel total drag coefficient (including hull drag, additional drag, etc.), D_sys is the quadratic term coefficient of the vessel total drag, G_sys is the external excitation caused by the environment (such as wind and wave force), T_prop is the thrust generated by the propulsion device, T_res is the drag generated by the engine, and T_load is the external load carried by the vessel;
the resistance t_res generated by the engine can be expressed as:
T_res＝f(V,N)-T_prop
wherein N is the rotation speed of the engine, f (V, N) is a function of the ship speed and the rotation speed of the engine, and is the resistance generated by the engine under a given working condition;
the thrust generated by the propulsion device can be expressed as:
T_prop＝f(N)*A*ρ*(M-M_0)^2
where M is the rotational speed of the propulsion device, f (M) is the efficiency function of the rotational speed, A is the effective area of the propulsion device, ρ is the density of water, and M_0 is the thrust-free rotational speed of the propulsion device.
Wherein solving the overall system equation using the Euler method includes,
discretizing the time into time steps delta t with equal intervals, and using n to represent the number of the time steps;
initializing conditions, namely setting initial time t0 and initial state variable values of all equipment components;
iterative solution, for each time step n=1, 2..the following steps are repeated:
calculating the current time t=t0+n×Δt;
the next time step value of the state variable of each device component is calculated according to the overall system equation established by the lumped parameter method, and for the device component i, the following value can be expressed as:
x_i[n+1]＝x_i[n]+Δt*f_i(x_1[n],x_2[n],...,x_N[n])
wherein x_i [ n ] represents the state variable value of device component i at time step n, and f_i represents the rate of change function of the state variable of device component i;
after the solution is completed, a state variable value x_i [ n ] of the device component at each time step is obtained, wherein i represents the device component number, and n represents the time step number.
Wherein determining a rate of change function f_i of the state variable for the device component comprises:
the rate of change function is expressed for the engine using the following form:
f_i＝(P_i-P_load)/(V_i*η_i)
where p_i is the output power of the host device, p_load is the load power, v_i is the voltage of the motor, η_i is the efficiency of the motor;
the rate of change function is expressed for the propulsion device using the following form:
f_i＝(T_i-T_res)/J_i
wherein T_i is the output thrust of the propulsion device, T_res is the resistance thrust, and J_i is the moment of inertia of the propulsion device;
for transmissions based on factors such as transmission efficiency and transmission ratio, the rate of change function is expressed using the following form:
f_i＝(T_i-T_load)/(J_i*η_i)
where T_i is the output torque of the transmission, T_load is the load torque, J_i is the moment of inertia of the transmission, and η_i is the transmission efficiency of the transmission.
Wherein, verifying and correcting the established ship power system model comprises:
collecting actual operation data, test results or known performance data of a ship power system, including data of ship speed, thrust, rotating speed and fuel consumption, and comparing and verifying the data with model prediction results;
identifying and calibrating parameters in the model by using the collected data, and adjusting the parameters in the model by comparing a model prediction result with actual data so that the model can predict the actual situation more accurately;
verifying the accuracy and applicability of the model by using an independent data set or experimental result, and comparing the difference between the model prediction result and the actual observation value;
comparing the model prediction result with the actual observation value to analyze errors, and carrying out model correction and adjustment according to the error analysis result;
and further verifying the corrected model, optimizing according to the verification result, and repeating the processes of model verification and correction until the model is stable.
The invention is suitable for various ship power systems, including ships of different types and scales, and can be used for modeling different types of power devices and propulsion devices by modeling the ship power system based on the lumped parameter method. The lumped parameter modeling process is simplified and faster than the detailed physical model-based modeling approach, and by using parameterized models and simplified mathematical expressions, a system model can be built and solved faster. The method is suitable for a real-time application scene and can be used for a real-time simulation and control system. By using a simplified model and efficient solution algorithm, it is possible to run and respond in a real-time environment. By establishing transfer relationships and energy balance equations between components, interactions and energy transfer between the various components can be accurately described.
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The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. Several embodiments of the present disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar or corresponding parts and in which:
fig. 1 is a flowchart showing a rapid modeling method for a ship power system based on a lumped parameter method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, the "plurality" generally includes at least two.
It should be understood that although the terms first, second, third, etc. may be used to describe … … in embodiments of the present invention, these … … should not be limited to these terms. These terms are only used to distinguish … …. For example, the first … … may also be referred to as the second … …, and similarly the second … … may also be referred to as the first … …, without departing from the scope of embodiments of the present invention.
It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrase "if determined" or "if detected (stated condition or event)" may be interpreted as "when determined" or "in response to determination" or "when detected (stated condition or event)" or "in response to detection (stated condition or event), depending on the context.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a commodity or device comprising such element.
The simulation of the vessel power system may include a simulation of a pipe network system and a simulation of a vessel power plant. For the simulation of the ship pipe network system, a Computational Fluid Dynamics (CFD) method can be used for simulating the flow and heat transfer behaviors of the fluid in the pipelines and the components, and the CFD method is used for calculating parameters such as the speed, the pressure and the temperature distribution of the fluid through a meshing and numerical solving method based on a Navier-Stokes equation and a heat conduction equation. However, the simulation of the pipe network system has the problems of high computational complexity, difficult grid generation and solution method selection and the like. Simulation of large-scale pipe network systems requires high performance computing resources and long computing time. In addition, accurate boundary condition and physical parameter input is also a challenge.
The simulation of a marine power plant may take a number of forms, and for internal combustion engines (such as diesel or gas turbines) may be modeled using thermodynamic models and kinetic equations. For propulsion devices (such as propellers or water jet propellers), simulations may be performed using thrust calculation formulas or CFD methods. For a transmission, simulation can be performed using a multi-body dynamics model or a transmission vibration analysis method. There are, however, simulations of marine power plants involving coupling and complex nonlinear behavior in a number of physical fields. Modeling and simulation processes require accurate parameters and boundary conditions, as well as appropriate numerical methods and computing techniques. The accuracy of the parameters and the availability of data may have an impact on the accuracy of the modeling results.
As shown in fig. 1, the invention discloses a rapid modeling method for a ship power system based on a lumped parameter method, which comprises the following steps:
s1, determining system boundaries and equipment components of a ship power system, and determining equipment components to be modeled based on coupling relations and signal transmission paths among the equipment components based on characteristics and functions of the ship power system, wherein the equipment components comprise a host device, a propulsion device and a transmission device.
In marine power systems, there is a close coupling relationship and signal transmission paths between the various equipment components. In one embodiment, the host device transmits power to the propulsion device through the transmission device, and the propulsion device converts the power into propulsion force to drive the ship to advance. Signals (e.g., torque, rotational speed, temperature, etc.) are transferred and interacted between equipment components through mechanical connections, sensors, and a control system.
The rapid modeling method based on the lumped parameter method can effectively model the ship power system, and determining the system boundary and equipment components of the ship power system is a key step for establishing the lumped parameter model. In one embodiment, determining the system boundaries of the vessel's power system refers to determining the ranges and boundaries to be included in the model. The main energy conversion and transmission processes that need to be covered are determined taking into account the functions and characteristics of the ship's power system. In general, system boundaries should include host devices, propulsion devices, transmission devices, and equipment and subsystems directly related to these components.
Based on the characteristics and functions of the vessel's power system, the equipment components that need to be modeled are determined. In one embodiment, the primary equipment assembly generally includes a host device, a propulsion device, and a transmission device. Furthermore, additional equipment closely related to the vessel's power system, such as fuel supply systems, cooling systems, lubrication systems, etc., may be included, depending on the particular needs.
In determining the device components, the flow of energy and the path of the signal transfer are taken into account. The energy transmission path between the equipment components is determined, including power transmission, heat transmission, fluid transmission, and the like. The signal transmission path between the equipment components is determined, and the signal transmission path comprises a sensor, a control system, a signal interface and the like.
S2, defining parameters and initial conditions of each equipment component, wherein the parameters comprise input signals and output signals, the input signals comprise control signals, environment conditions or output signals of other equipment components, the output signals comprise rotating speed, thrust force and torque, and the initial conditions comprise initial states, initial values and initial inputs of each equipment component.
The critical parameters and their interactions are considered in determining the system boundaries and device components. In one embodiment, key parameters that have a greater impact on the performance of the marine propulsion system, such as power, torque, rotational speed, temperature, etc., are determined taking into account interactions and coupling relationships between the plant components.
An input signal and an output signal for each device component are determined. In one embodiment, the input signal refers to a signal entering a device component and may include a control signal, an environmental condition, or an output signal of another device component. The output signal is a signal generated by the equipment components, such as rotational speed, thrust, torque, etc.
In one embodiment, for a host device, the input signals may include fuel supply, cooling water temperature and pressure, and the like. The output signal may include a host rotational speed, engine power, etc. For propulsion devices, the input signal may include torque and rotational speed output by the host machine, etc. The output signal may include thrust, propeller rotational speed, etc. For a transmission, the input signal may include torque and rotational speed output by the host, and the output signal may include rotational speed and torque of the drive shaft.
In one embodiment, the initial conditions refer to initial states, initial values, and initial inputs for each device component at the time the model begins simulation.
In one embodiment, for a host device, the initial conditions may include an initial rotational speed, an initial temperature, and an initial pressure of the host, etc. For a propulsion device, the initial conditions may include an initial rotational speed of the propulsion device, a propeller position, and the like. For a transmission, the initial conditions may include an initial rotational speed and an initial torque of the transmission shaft, etc.
In certain embodiments, parameters and initial conditions in a marine power system may change over time and operating conditions. Taking the interaction and coupling relation between the equipment components into consideration, the change of parameters and initial conditions is ensured to be accurately reflected in the model.
And S3, building a device component model, and selecting a model equation to model each device component based on the parameter characteristics of each device component.
The rapid modeling method based on the lumped parameter method can select and select a proper model equation to establish a device component model in the ship power system according to specific requirements and characteristics of the ship power system.
In selecting model equations, the selected model equations should accurately describe the performance characteristics and behavior of the device components, have high computational efficiency, so as to achieve real-time performance in rapid modeling, and should also be based on available parametric characteristic data, such as performance curves, measured data, etc., provided by the device manufacturer. Thus, the device component model needs to comprehensively consider factors such as device characteristics, data availability, model complexity, and computing requirements.
In one embodiment, building the equipment component model includes, host device modeling, propulsion device modeling, and transmission device modeling;
the host device modeling includes using a transfer function model to represent the power output of the engine, using a first order inertia model to represent the acceleration response of the engine, and building an engine model:
T_engine(s)＝K_engine/(Ts+1)
wherein T_Engine(s) is the transfer function of the engine, K_Engine is the gain parameter, and T is the time constant;
using the relation between the mass and the force to represent the change of the acceleration of the ship, and building a kinetic model of the acceleration of the ship according to the force output by the engine and the mass of the ship:
a_ship＝F_engine/m_ship
where a_ship is the acceleration of the ship, f_engine is the force output by the engine, and m_ship is the mass of the ship.
In one embodiment, the propulsion device modeling includes using a transfer function model to represent propulsion characteristics of the propeller, using a second order inertial model to represent propulsion response of the propeller, and building a propeller model:
T_propeller(s)＝(K_propeller*ω_n^2)/(s^2+2ξω_n s+ω_n^2)
wherein, T_propeller(s) is the transmission function of the propeller, K_propeller is the gain parameter, omega_n is the natural frequency, and xi is the damping ratio;
according to the propulsion characteristics of the propeller and the motion state of the ship, a dynamic model of the propulsion is established, and the following relationship exists between the transmission function of the propulsion and the propeller and the speed of the ship:
F_propulsion＝T_propeller*ω_propeller*r_propeller-F_resistance
wherein F_propulsion is propulsion, T_propeller is a transmission function of a propeller, omega_propeller is the rotating speed of the propeller, r_propeller is the radius of the propeller, and F_resistance is the resistance of the ship.
In one embodiment, the transmission modeling includes using a transfer function model to represent transmission characteristics of the transmission, using a first order inertial model to represent transmission response, building a transmission model:
T_transmission(s)＝K_transmission/(Ts+1)
where t_ transmission(s) is the transmission function of the transmission, k_transmission is the gain parameter, and T is the time constant;
according to the output of the transmission device and the input of the propeller, a transmission relation between the axis and the propeller is established, the output of the transmission device is directly connected to the input of the propeller, and an axis and a propeller model is established:
ω_propeller＝T_transmission*ω_engine
where ω_propeller is the rotational speed of the propeller, t_transmission is the transmission function of the transmission, and ω_engine is the rotational speed of the engine.
S4, establishing an overall system model, and constructing an overall ship power system model according to the coupling relation among the equipment components and the input and output signal transmission paths of the equipment components.
The coupling relationships between the device components and the energy transfer and signaling mechanisms between the device components are determined. For example, the output of the host device will be the input to the propulsion device and the transmission will transmit the torque and rotational speed of the host to the propulsion device. The direction of flow and manner of delivery of the signals in the system is determined based on the paths of the input signals and the output signals, which may be control signals, environmental conditions, or output signals of other equipment components.
In one embodiment, building an overall system model includes:
based on the dynamic balance equation, an integral ship dynamic system equation is constructed according to the coupling relation of all equipment components and the inertia, resistance, external excitation, propulsion and load factors of a ship system, and the integral dynamic balance equation of the ship dynamic system can be expressed as:
M_sys*dV/dt+(C_sys+C_prop)*V+(D_sys+D_prop)*V^2+G_sys＝T_prop-T_res-T_load
where V is the vessel speed, M_sys is the vessel total inertial mass, C_sys is the vessel total drag coefficient (including hull drag, additional drag, etc.), D_sys is the quadratic term coefficient of the vessel total drag, G_sys is the external excitation caused by the environment (such as wind and wave force), T_prop is the thrust generated by the propulsion device, T_res is the drag generated by the engine, and T_load is the external load carried by the vessel;
the resistance t_res generated by the engine can be expressed as:
T_res＝f(V,N)-T_prop
wherein N is the rotation speed of the engine, f (V, N) is a function of the ship speed and the rotation speed of the engine, and is the resistance generated by the engine under a given working condition;
the thrust generated by the propulsion device can be expressed as:
T_prop＝f(N)*A*ρ*(M-M_0)^2
where M is the rotational speed of the propulsion device, f (M) is the efficiency function of the rotational speed, A is the effective area of the propulsion device, ρ is the density of water, and M_0 is the thrust-free rotational speed of the propulsion device.
And S5, solving an integral system equation by using an Euler method, verifying the ship power system model, and adjusting and correcting according to a verification result.
By solving the overall system equation, validating the model, adjusting and correcting the model, a more accurate and reliable model of the ship's power system can be established. The model can be used for system analysis, performance prediction, optimization design and other applications, and the efficiency and reliability of the ship power system are improved.
By solving the overall system equation, the state and response of the ship power system at different time points can be obtained. And comparing the output result of the model with actual observation data, and verifying the accuracy of the model. Verification may be performed using experimental data, historical data, or other reliable data sources. And adjusting and correcting the model according to the verification result. This may include adjusting model parameters, refining model equations, modifying coupling relationships, and the like. Model verification, tuning and correction are an iterative process. After adjustment and correction, the accuracy of the model is again verified. If the model output is consistent with the actual observations, the model can be used for prediction and analysis. If there is still a discrepancy, the model needs to be further adapted and revised until the model is able to accurately describe the behavior of the vessel's power system.
In one embodiment, solving the overall system equation using the euler method includes,
discretizing the time into time steps delta t with equal intervals, and using n to represent the number of the time steps;
initializing conditions, namely setting initial time t0 and initial state variable values of all equipment components;
iterative solution, for each time step n=1, 2..the following steps are repeated:
calculating the current time t=t0+n×Δt;
the next time step value of the state variable of each device component is calculated according to the overall system equation established by the lumped parameter method, and for the device component i, the following value can be expressed as:
x_i[n+1]＝x_i[n]+Δt*f_i(x_1[n],x_2[n],...,x_N[n])
wherein x_i [ n ] represents the state variable value of device component i at time step n, and f_i represents the rate of change function of the state variable of device component i;
after the solution is completed, a state variable value x_i [ n ] of the device component at each time step is obtained, wherein i represents the device component number, and n represents the time step number.
In one embodiment, determining the rate of change function f_i of the state variable for the device component includes:
in one embodiment, the rate of change function is expressed for the engine using the following form:
f_i＝(P_i-P_load)/(V_i*η_i)
where p_i is the output power of the host device, p_load is the load power, v_i is the voltage of the motor, η_i is the efficiency of the motor;
in one embodiment, the rate of change function is expressed for the propulsion device using the following form:
f_i＝(T_i-T_res)/J_i
wherein T_i is the output thrust of the propulsion device, T_res is the resistance thrust, and J_i is the moment of inertia of the propulsion device;
in one embodiment, for a transmission based on factors such as transmission efficiency and transmission ratio, the rate of change function is expressed using the following form:
f_i＝(T_i-T_load)/(J_i*η_i)
where T_i is the output torque of the transmission, T_load is the load torque, J_i is the moment of inertia of the transmission, and η_i is the transmission efficiency of the transmission.
In one embodiment, verifying and modifying the established model of the marine propulsion system comprises:
collecting actual operation data, test results or known performance data of a ship power system, including data of ship speed, thrust, rotating speed and fuel consumption, and comparing and verifying the data with model prediction results;
identifying and calibrating parameters in the model by using the collected data, and adjusting the parameters in the model by comparing a model prediction result with actual data so that the model can predict the actual situation more accurately;
verifying the accuracy and applicability of the model by using an independent data set or experimental result, and comparing the difference between the model prediction result and the actual observation value;
comparing the model prediction result with the actual observation value to analyze errors, and carrying out model correction and adjustment according to the error analysis result;
and further verifying the corrected model, optimizing according to the verification result, and repeating the processes of model verification and correction until the model is stable.
The invention models the ship power system based on the lumped parameter method, is suitable for various ship power systems, and has the advantages of universality, rapidness, instantaneity and good coupling property.
It should be noted that the computer readable medium described in the present disclosure may be a computer readable signal medium or a computer readable storage medium, or any combination of the two. The computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples of the computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this disclosure, a computer-readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In the present disclosure, however, the computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, with the computer-readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: electrical wires, fiber optic cables, RF (radio frequency), and the like, or any suitable combination of the foregoing.
The computer readable medium may be contained in the electronic device; or may exist alone without being incorporated into the electronic device.
Computer program code for carrying out operations of the present disclosure may be written in one or more programming languages, including an object oriented programming language such as Java, smalltalk, C ++ and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider).
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The units involved in the embodiments of the present disclosure may be implemented by means of software, or may be implemented by means of hardware. Wherein the names of the units do not constitute a limitation of the units themselves in some cases.
The foregoing description of the preferred embodiments of the present invention has been presented for purposes of clarity and understanding, and is not intended to limit the invention to the particular embodiments disclosed, but is intended to cover all modifications, alternatives, and improvements within the spirit and scope of the invention as outlined by the appended claims.
Claims (6)
1. A rapid modeling method for a ship power system based on a lumped parameter method comprises the following steps:
s1, determining a system boundary and equipment components of a ship power system, and determining equipment components to be modeled based on the coupling relation and the signal transmission path between the equipment components based on the characteristics and the functions of the ship power system, wherein the equipment components comprise a host device, a propulsion device and a transmission device;
s2, defining parameters and initial conditions of each equipment component, wherein the parameters comprise input signals and output signals, the input signals comprise control signals, environment conditions or output signals of other equipment components, the output signals comprise rotating speed, thrust and torque, and the initial conditions comprise initial states, initial values and initial inputs of each equipment component;
s3, establishing a device component model, and selecting a model equation to model each device component based on the parameter characteristics of each device component;
s4, establishing an overall system model, and constructing an overall ship power system model according to the coupling relation among the equipment components and the input and output signal transmission paths of the equipment components;
s5, solving an integral system equation by using an Euler method, verifying a ship power system model, and adjusting and correcting according to a verification result;
establishing a device assembly model comprises host device modeling, propulsion device modeling and transmission device modeling;
the host device modeling includes, using a transfer function model to represent a power output of the engine, using a first-order inertia model to represent an acceleration response of the engine, and establishing an engine model:
T_engine(s) = K_engine / (Ts + 1)
wherein T_Engine(s) is the transfer function of the engine, K_Engine is the gain parameter, and T is the time constant;
using the relation between the mass and the force to represent the change of the acceleration of the ship, and building a kinetic model of the acceleration of the ship according to the force output by the engine and the mass of the ship:
a_ship = F_engine / m_ship
where a_ship is the acceleration of the ship, f_engine is the force output by the engine, and m_ship is the mass of the ship;
the propulsion device modeling comprises the steps of representing the propulsion characteristics of the propeller by using a transfer function model, representing the propulsion response of the propeller by using a second-order inertia model, and establishing a propeller model:
T_propeller(s) = (K_propeller * ω_n^2) / (s^2 + 2ξω_n s + ω_n^2)
wherein, T_propeller(s) is the transmission function of the propeller, K_propeller is the gain parameter, omega_n is the natural frequency, and xi is the damping ratio;
according to the propulsion characteristics of the propeller and the motion state of the ship, a dynamic model of the propulsion is established, and the following relationship exists between the transmission function of the propulsion and the propeller and the speed of the ship:
F_propulsion = T_propeller * ω_propeller * r_propeller - F_resistance
wherein F_propulsion is propulsion, T_propeller is a transmission function of a propeller, omega_propeller is the rotating speed of the propeller, r_propeller is the radius of the propeller, and F_resistance is the resistance of the ship;
the modeling of the transmission device comprises the steps of representing the transfer characteristic of the transmission device by using a transfer function model, representing the response of the transmission device by using a first-order inertia model, and establishing a transmission device model:
T_transmission(s) = K_transmission / (Ts + 1)
where t_ transmission(s) is the transmission function of the transmission, k_transmission is the gain parameter, and T is the time constant;
according to the output of the transmission device and the input of the propeller, a transmission relation between the axis and the propeller is established, the output of the transmission device is directly connected to the input of the propeller, and an axis and a propeller model is established:
ω_propeller = T_transmission * ω_engine
where ω_propeller is the rotational speed of the propeller, t_transmission is the transmission function of the transmission, and ω_engine is the rotational speed of the engine.
2. A rapid modeling method for a ship power system based on a lumped parameter method as defined in claim 1,
the building of the overall system model comprises the following steps:
based on a dynamic balance equation, constructing an integral ship dynamic system equation according to the coupling relation of all equipment components and the inertia, resistance, external excitation, propulsion and load factors of a ship system, wherein the integral dynamic balance equation of the ship dynamic system is expressed as:
M_sys * dV/dt + (C_sys + C_prop) * V + (D_sys + D_prop) * V^2 + G_sys = T_prop - T_res - T_load
wherein V is the ship speed, M_sys is the total inertial mass of the ship, C_sys is the total resistance coefficient of the ship, the total resistance coefficient comprises the ship body resistance and additional resistance, D_sys is the quadratic term coefficient of the total resistance of the ship, G_sys is the external excitation caused by environment, T_prop is the thrust generated by a propulsion device, T_res is the resistance generated by an engine, and T_load is the external load borne by the ship;
the resistance t_res generated by the engine is expressed as:
T_res = f(V, N) - T_prop
wherein N is the rotation speed of the engine, f (V, N) is a function of the ship speed and the rotation speed of the engine, and is the resistance generated by the engine under a given working condition;
the thrust generated by the propulsion means is expressed as:
T_prop = f(M) * A * ρ * (M - M_0)^2
where M is the rotational speed of the propulsion device, f (M) is the efficiency function of the rotational speed, A is the effective area of the propulsion device, ρ is the density of water, and M_0 is the thrust-free rotational speed of the propulsion device.
3. A rapid modeling method for a ship power system based on a lumped parameter method as defined in claim 1,
solving the overall system equation using the euler method includes,
discretizing the time into time steps delta t with equal intervals, and using n to represent the number of the time steps;
initializing conditions, namely setting initial time t0 and initial state variable values of all equipment components;
the solution is iterated, for each time step n=1, 2..the following steps are repeated:
calculating the current time t=t0+n×Δt;
according to the overall system equation established by the lumped parameter method, the value of the next time step of the state variable of each equipment component is calculated, and for the equipment component i, the following is expressed as:
x_i[n+1] = x_i[n] + Δt * f_i(x_1[n], x_2[n], ..., x_N[n])
wherein x_i [ n ] represents the state variable value of device component i at time step n, and f_i represents the rate of change function of the state variable of device component i;
after the solution is completed, a state variable value x_i [ n ] of the device component at each time step is obtained, wherein i represents the device component number, and n represents the time step number.
4. A rapid modeling method for a ship power system based on lumped parameter method as defined in claim 3,
determining a rate of change function f_i of the state variable for the device component includes:
the rate of change function is expressed for the engine using the following form:
f_i = (P_i - P_load) / (V_i * η_i)
where p_i is the output power of the host device, p_load is the load power, v_i is the voltage of the motor, η_i is the efficiency of the motor;
the rate of change function is expressed for the propulsion device using the following form:
f_i = (T_i - T_res) / J_i
wherein T_i is the output thrust of the propulsion device, T_res is the resistance thrust, and J_i is the moment of inertia of the propulsion device;
for a transmission based on transmission efficiency and ratio factors, the rate of change function is expressed using the following form:
f_i = (T_i - T_load) / (J_i * η_i)
where T_i is the output torque of the transmission, T_load is the load torque, J_i is the moment of inertia of the transmission, and η_i is the transmission efficiency of the transmission.
5. A rapid modeling method for a ship power system based on a lumped parameter method as defined in claim 1,
verifying and correcting the established ship power system model comprises the following steps:
collecting actual operation data, test results or known performance data of a ship power system, including data of ship speed, thrust, rotating speed and fuel consumption, and comparing and verifying the data with model prediction results;
identifying and calibrating parameters in the model by using the collected data, and adjusting the parameters in the model by comparing a model prediction result with actual data so that the model can predict the actual situation more accurately;
verifying the accuracy and applicability of the model by using an independent data set or experimental result, and comparing the difference between the model prediction result and the actual observation value;
comparing the model prediction result with the actual observation value to analyze errors, and carrying out model correction and adjustment according to the error analysis result;
and further verifying the corrected model, optimizing according to the verification result, and repeating the processes of model verification and correction until the model is stable.
6. A rapid modeling device for a ship power system based on a lumped parameter method comprises the following components:
at least one processor; and
at least one memory including computer program code,
wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to perform the method of any of claims 1-5.
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| CN107902042A (en) * | 2017-10-27 | 2018-04-13 | 华中科技大学 | A kind of ship multiaxis electric propulsion system based on Simulink models |
| CN113642105A (en) * | 2021-08-03 | 2021-11-12 | 中国船舶重工集团公司第七一九研究所 | Multi-scale model construction method and device of ship power system and electronic equipment |
| CN115146392A (en) * | 2022-07-25 | 2022-10-04 | 江南造船(集团)有限责任公司 | Ship pipeline system modeling simulation method, computer storage medium and equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107902042A (en) * | 2017-10-27 | 2018-04-13 | 华中科技大学 | A kind of ship multiaxis electric propulsion system based on Simulink models |
| CN113642105A (en) * | 2021-08-03 | 2021-11-12 | 中国船舶重工集团公司第七一九研究所 | Multi-scale model construction method and device of ship power system and electronic equipment |
| CN115146392A (en) * | 2022-07-25 | 2022-10-04 | 江南造船(集团)有限责任公司 | Ship pipeline system modeling simulation method, computer storage medium and equipment |
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