Marine diesel generating set single shafting torsional vibration analysis model and modeling method thereof

Abstract

A ship diesel generating set single shafting torsional vibration analysis model and a modeling method thereof belong to the field of vibration and noise reduction of ship equipment, and comprise a diesel engine speed regulation system model, a diesel engine acting model, a diesel engine torque synthesis model and an electromechanical coupling analysis model established among flexible shafting models based on transmission shaft rotating speed signals; establishing a power grid coupling analysis model among the generator model, the excitation system model and the load system model based on voltage and current signals; all the models are coupled based on the electromechanical coupling analysis model and the power grid coupling analysis model, and a shaft system torsional vibration analysis model of the ship diesel generator set single-machine control system and shaft system torsional vibration is obtained. According to the application, the coupling effect analysis of the single-machine speed regulation control system, the generator excitation system, the power grid load system and the shaft system torsional vibration system of the ship diesel generating set in the island mode can be realized, the single-machine stable transient vibration characteristics of the ship diesel generating set can be conveniently researched, and support is provided for the design optimization of related system parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ship equipment vibration and noise reduction, and particularly relates to a ship diesel generator set single machine shafting torsional vibration analysis model and a modeling method thereof. BACKGROUND

[0002] The ship diesel generator set is mostly an island power station system. Compared with the unlimited capacity power station system on land, the island power station system mostly uses a diesel engine as a prime mover, and the power supply capacity is small, which is generally regarded as a limited large power system. Moreover, the load of the island power station system changes frequently, and the start-stop switching of high-power load equipment has a large impact on the load of the island power station system power grid, thereby forming a transient impact torque on the shafting of the single diesel generator set, which seriously endangers the safe operation of the shafting of the diesel generator set.

[0003] When the diesel engine is running, the vibration (such as shafting torsional vibration) of the mechanical transmission system will cause the shafting speed to fluctuate, and the diesel engine speed regulation system will also be affected after picking up the speed signal. In turn, the adjustment behavior of the diesel engine speed regulation system will also affect the shafting torsional vibration. The change of the power grid load affects the operation of the generator through the voltage and current signals, and further affects the operation of the diesel engine. That is, there is a problem of mutual coupling and coordinated matching among the diesel engine speed regulation control system, the generator excitation control system, the power grid load system, and the mechanical transmission system.

[0004] However, the current related researches on the diesel engine speed regulation system, the generator excitation system, the power grid load system, and the mechanical transmission system are independent of each other. There is a lack of corresponding research on the shafting torsional vibration characteristics under the influence of multi-system coupling. SUMMARY

[0005] The present application provides a generator set single machine shafting torsional vibration analysis model and a modeling method thereof, which can solve the technical problem in the prior art that the mutual coupling of the diesel engine speed regulation control system, the generator excitation system, the power grid load system, and the mechanical transmission system is not considered in the shafting torsional vibration transient calculation of the ship diesel generator set and the parameter setting of the PID controller of the diesel engine speed regulation control system.

[0006] In a first aspect, the present application provides a modeling method of a ship diesel generator set single machine shafting torsional vibration analysis model, and the method comprises: respectively constructing a speed regulation controller model, a diesel engine work model, a diesel engine torque synthesis model, a flexible shafting model, a generator model, an excitation system model, and a load system model; establishing an electromechanical coupling analysis model among the diesel engine speed regulation system model, the diesel engine work model, the diesel engine torque synthesis model, and the flexible shafting model based on the transmission shaft speed signal; and establishing an electric grid coupling analysis model among the generator model, the excitation system model, and the load system model based on the voltage and current signals. The single machine control system of the marine diesel generator set and the shafting torsional vibration analysis model of the shafting torsional vibration are coupled based on an electromechanical coupling analysis model and a power grid coupling analysis model.

[0007] In combination with the first aspect, in an implementation, the input quantity of the diesel engine working model includes a control current output by the governing controller model, and the output quantity includes a cylinder average indicated pressure.

[0008] In combination with the first aspect, in an implementation, the input quantity of the diesel engine torque synthesis model includes the cylinder average indicated pressure output by the diesel engine working model, and the output quantity includes a cylinder average torque and a cylinder additional torque.

[0009] In combination with the first aspect, in an implementation, the input quantity of the generator model includes the voltage and current signals output by the load system model and the excitation system model, and the output quantity includes an electromagnetic torque.

[0010] In combination with the first aspect, in an implementation, the input quantity of the flexible shafting model includes the cylinder average torque and the cylinder additional torque output by the diesel engine working model, and the electromagnetic torque output by the generator model, and the output quantity includes the transmission shaft speed signal.

[0011] In combination with the first aspect, in an implementation, the excitation system model adopts a phase-compound brushless excitation control model.

[0012] In combination with the first aspect, in an implementation, the load system model adopts a static load model.

[0013] In combination with the first aspect, in an implementation, the method further includes: The stator current in the generator model is collected by adjusting the load of the load system model, the stator current is compared with the stator current of the generator in the diesel generator set actually running under the same load, if the difference is not more than a maximum threshold, it is determined that the shafting torsional vibration analysis model is successfully constructed, if the difference is more than the maximum threshold, it is further determined that the shafting torsional vibration analysis model is not successfully constructed, and the control parameters of the governing controller model and / or the elastic coupling parameters of the flexible shafting model in the shafting torsional vibration analysis model are updated.

[0014] In combination with the first aspect, in an implementation, the method further includes: By adjusting the load of the load system model, the drive shaft speed signal is collected and compared with the drive shaft speed signal of the diesel generator set actually operating under the same load. If the difference does not exceed the maximum threshold, it is determined that the shaft system torsional vibration analysis model is successfully constructed. If the difference exceeds the maximum threshold, it is determined that the shaft system torsional vibration analysis model is unsuccessful, and the control parameters of the speed controller model in the shaft system torsional vibration analysis model and / or the elastic coupling parameters of the flexible shaft system model are updated.

[0015] In a second aspect, an embodiment of the present application provides a torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set, and the model is modeled using the modeling method of the torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set.

[0016] The beneficial effects of the technical solutions provided in the embodiments of the present application include: This model comprehensively considers the diesel engine speed control system, generator excitation system, grid load system, and mechanical transmission system, and can realize the simulation analysis of the torsional vibration of the single-unit shaft system of the diesel-generator unit under the conditions of multi-system coupling.

[0017] It can provide support for the PID controller parameter tuning of the diesel-generator speed control system under the influence of shaft system torsional vibration and grid load, avoiding resonance between the diesel engine speed control system and the mechanical transmission system, generator excitation system, and grid load system, which may affect the unit's operating stability and shaft system safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of an embodiment of a method for modeling a torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set according to the present application; Figure 2 This is a schematic diagram of the structure of a rigid shaft system diesel engine speed control system in the prior art; Figure 3 This is a schematic structural diagram of a flexible shafting torsional vibration and diesel engine speed control coupling system in one embodiment of the present application; Figure 4 This is a schematic structural diagram of a shafting torsional vibration analysis model in one embodiment of the present application; Figure 5 This is a schematic diagram of the principle of a diesel engine working model in one embodiment of the present application; Figure 6 This is a structural diagram of an excitation system model in one embodiment of the present application; Figure 7 This is a load diagram under a continuous sudden load condition in a specific embodiment of the present application; Figure 8 This is a schematic diagram of the time domain variation of the generator stator A phase current under continuous sudden load conditions in a specific embodiment of the present application; Figure 9 This is a time domain speed diagram of the total time history of the flywheel end of a diesel engine in a specific embodiment of the present application; Figure 10 This is a schematic diagram of the time domain speed of the flywheel end of the diesel engine during the loading process of the load L1 in a specific embodiment of the present application; Figure 11 This is a schematic diagram of the time domain speed of the flywheel end of the diesel engine during the loading process of the load L2 in a specific embodiment of the present application; Figure 12 This is a schematic diagram of the time domain speed of the flywheel end of the diesel engine during the loading process of load L3 in a specific embodiment of the present application; Figure 13 This is a schematic diagram of the dynamic torque response of the coupling during each loading process in a specific embodiment of the present application; Figure 14 This is a schematic diagram of the torque spectrum of the coupling during each loading process in a specific embodiment of the present application; Figure 15 This is a schematic diagram of the dynamic torque response of the generator shaft during each loading process in a specific embodiment of the present application; Figure 16 Schematic diagram of the generator shaft torque spectrum in each loading process in a specific embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0021] In a first aspect, an embodiment of the present application provides a method for modeling a torsional vibration analysis model of a single-machine shaft system of a marine diesel generator set.

[0022] In one embodiment, referring to Figure 1 and Figure 4 , Figure 1 This is a flow chart of an embodiment of a modeling method for a single-unit shafting torsional vibration analysis model of a marine diesel generator set of the present application. Figure 4 Schematic diagram of the structure of the shaft torsional vibration analysis model in one embodiment of the present application. Figure 1 and Figure 4 As shown in Figure 2, the modeling method for the torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set includes: Step S1: construct a speed controller model, a diesel engine work model, a diesel engine torque synthesis model, a flexible shaft system model, a generator model, an excitation system model, and a load system model respectively.

[0023] In step S2, an electromechanical coupling analysis model is established between the diesel engine speed control system model, the diesel engine power model, the diesel engine torque synthesis model, and the flexible shafting model based on the transmission shaft speed signal. A power grid coupling analysis model is established between the generator model, the excitation system model, and the load system model based on the voltage and current signals.

[0024] Step S3: coupling all models based on the electromechanical coupling analysis model and the power grid coupling analysis model to obtain a shafting torsional vibration analysis model of a single-unit control system of a marine diesel generator set and shafting torsional vibration.

[0025] Step S2 and step S3 can be performed simultaneously.

[0026] Traditional diesel engine speed control system research does not consider the influence of mechanical transmission system shaft torsional vibration. In the corresponding simulation design model, the mechanical transmission system shaft is regarded as a rigid rotor, such as Figure 2 shown.

[0027] The present invention considers the elasticity of the shaft system and first establishes an electromechanical coupling analysis model. In the electromechanical coupling analysis model, the rigid rotor module is replaced by a flexible shaft system model, thereby coupling the shaft system torsional vibration into the diesel engine speed control system to form a closed-loop control structure. Figure 3 shown.

[0028] The diesel engine speed control system model uses the PID controller model to output the control current to the diesel engine work model. The diesel engine work model acts as an actuator to adjust the rack displacement, thereby affecting the injection volume of the plunger pump, and finally converting it into a change in the cylinder gas pressure, thereby changing the excitation torque level of the shaft torsional vibration.

[0029] Among them, the speed controller model, also known as PID controller or controller, is used to simulate the diesel engine speed control system PID controller, which can control the speed of the diesel generator set.

[0030] The diesel engine power model, also known as the actuator, is used to simulate the diesel engine's power capacity regulation. It includes the controller current-rack displacement curve, the rack displacement-injection amount curve, and the injection amount-cylinder pressure coefficient curve. The actuator receives the current signal i output by the PID controller and ultimately outputs the cylinder average indicated pressure.

[0031] The diesel engine torque synthesis model, diesel engine torque synthesis is also called diesel engine, which is used to simulate the average torque and additional torque of the diesel generator set and introduce the reciprocating excitation force of the diesel engine into the coupling analysis model.

[0032] A flexible shafting model is used to simulate the shafting of a diesel generator set transmission system, considering the elasticity of the shafting, replacing the previous rigid shafting module with a flexible shafting module, and coupling the shafting torsional vibration into the simulation model.

[0033] A generator model is used to simulate the synchronous generator in the diesel generator set, adopting a five-order engineering model.

[0034] An excitation system model is used to simulate the generator excitation system, adopting a phase compound excitation brushless excitation control model.

[0035] A load system model, also known as a grid load, is used to simulate various loads of the ship diesel generator set, adopting a constant impedance load model to simulate the electrical load.

[0036] In the shafting torsional vibration analysis model, if the PID controller parameters are not reasonably set, the characteristic frequency component of the shafting torsional vibration will exist in the control signal output by the control system due to the influence of the instantaneous speed feedback signal, thereby causing the existence of a component that can excite the characteristic frequency of the torsional vibration in the excitation torque generated by the cylinder pressure of the diesel engine, which will cause resonance and coupled oscillation when acting on the mechanical transmission system shafting. Through mechanical analysis, the controller parameters and the structure parameters of the flexible shafting can be optimized.

[0037] The present application comprehensively considers the shafting torsional vibration characteristics under the mutual coupling influence of the diesel engine speed control system, the generator excitation system, the grid load system, and the mechanical transmission system (i.e., the shafting torsional vibration system), which can more truly reflect the actual level of the shafting torsional vibration indicators of the diesel generator set in the island system under various working conditions.

[0038] Further, in an embodiment, the transfer function of the traditional simulation PID control law is shown in the following formula (1): (1), In the formula, represents the relationship between the output (control signal) of the controller and the input (error signal, i.e., the difference between the set value and the actual value), represents the proportional coefficient. represents the integral coefficient. represents the differential coefficient. represents the integral time constant. represents the differential time constant. S represents the complex frequency variable in Laplace transform.

[0039] Further, in an embodiment, the input quantity of the above diesel engine work model includes the control current output by the speed controller model, and the output quantity includes the average indicated pressure of the cylinder.

[0040] In this embodiment, the input quantity of the diesel engine work model includes the control current output by the speed controller model, and the output quantity includes the cylinder mean indicated pressure.

[0041] The diesel engine power model mainly includes the controller current-rack displacement curve, rack displacement-injection amount curve and injection amount-cylinder pressure coefficient curve, such as Figure 5 As shown in the figure, the actuator receives the current signal i output by the PID controller and converts it into the rack displacement signal x for the injection pump's adjustment rod. The injection pump calculates the injection quantity q based on the rack displacement signal x. The injection quantity is linearly related to the cylinder mean indicated pressure, with the proportionality coefficient k calculated based on experimental data fitting.

[0042] Furthermore, in one embodiment, the input of the diesel engine torque synthesis model includes the cylinder mean indicated pressure output by the diesel engine work model, and the output includes the cylinder mean torque and the cylinder additional torque.

[0043] In this embodiment, the total torque output by the diesel engine torque synthesis model is divided into two parts, namely, the average torque and the additional torque. The fluctuating torque accompanying the average torque is the additional torque. The role of the diesel engine torque synthesis model is to synthesize these two parts of torque based on the cylinder average indicated pressure. At the same time, the additional torque excitation is composed of the gas pressure torque and the reciprocating inertia torque of the diesel engine cylinder. The gas pressure torque can vary with the comprehensive coefficient k mentioned above. The base value of the reciprocating inertia torque is the result under rated operating conditions. The actual reciprocating inertia torque can be converted into a physical quantity that varies with the speed by the following formula (2): (2), Where, is the reciprocating inertia moment. n is the instantaneous speed. Indicates rated speed. Indicates the reciprocating inertia moment under rated working conditions.

[0044] Furthermore, in one embodiment, the input of the flexible shafting model includes the cylinder average torque and cylinder additional torque output by the diesel engine work model, and the electromagnetic torque output by the generator model, and the output includes the transmission shaft speed signal.

[0045] In this embodiment, a corresponding flexible shaft system model is established for the shaft system of the diesel generator transmission system. The model is established based on the principle of vibration differential equation. Here, an inertia is used to illustrate it. The vibration differential equation of the inertia is shown in the following formula (3): (3), Transforming formula (3) yields the following formula (4): (4), Where, angular acceleration of n inertia. angular velocity of n inertia. torsional angular displacement of n inertia. exciting torque, also called additional torque excitation. lumped inertia value of n inertia. absolute damping of n inertia. relative damping of n shaft section. stiffness value of n shaft section.

[0046] Based on the above modules, the torsional vibration model of the diesel generator set can be established.

[0047] Further, in an embodiment, the input of the generator model includes the above-mentioned voltage and current signals output by the load system model and the excitation system model, and the output includes the electromagnetic torque.

[0048] In this embodiment, the seven-order basic model of the three-phase synchronous motor is too complex and has poor flexibility, so in the actual processing process, the model is often reduced in order according to the actual needs, that is, an engineering application model. The present application preferably uses a five-order model.

[0049] From the seven-order basic model to the five-order engineering model, two kinds of assumption operations are needed: ignoring the stator winding transient, that is, , the stator voltage differential equation is converted into an algebraic equation. Assuming that in the stator voltage equation is equal to 1, the equation is linearized. The engineering model obtained through the above two kinds of assumption operations ignores the influence of the stator winding transient, but still considers the influence of the D, Q damping winding, the rotor dynamic and the excitation winding transient.

[0050] Further, in an embodiment, the excitation system model adopts a phase compound brushless excitation control model.

[0051] In this embodiment, the schematic diagram of the phase compound brushless excitation control model is as shown in Figure 5 The internal structure and working principle are as follows: the power supply unit converts the generator output voltage into the voltage required by the system through the links of voltage transformation, rectification, etc., and delivers it to the phase control and PID control units. The synchronous control unit makes the excitation voltage and the excitation current keep synchronous phase change. The voltage difference detection unit is used to monitor the error signal between the reference voltage and the actual voltage. The PID control unit is responsible for amplifying the voltage error signal to a certain order of magnitude. The phase control unit is responsible for further amplifying the signal. The main thyristor rectification unit is responsible for rectifying the armature current.

[0052] Further, in an embodiment, the load system model adopts a static load model.

[0053] In this embodiment, the instability of the island power system largely stems from the load equipment. The ship island power station studied in this invention has a wide variety of loads, such as incandescent lamps, air conditioners, compressors, pumps, fans, and electromechanical cabinets. The exact composition of the loads is difficult to determine, so this invention uniformly uses a static load model. Static load models can be divided into constant impedance load models and constant power load models. This invention prefers the constant impedance load model to simulate the power load.

[0054] In summary, the diesel engine drives the synchronous generator through an elastic coupling, and the generator is connected to various power loads through the power grid. Therefore, the diesel engine, synchronous generator and power grid load constitute an island power station system. The island power station system has frequent load changes and the system stability is slightly worse than that of the infinite power system. These characteristics put forward higher requirements for the stable operation of the diesel generator set in the island system. The load change of the power grid load causes the working state of the generator to change. The change of the working state of the generator is bound to affect the working state of the diesel engine, and the torsional vibration level of the transmission system shaft system will also change accordingly, and then the diesel engine speed control system will be feedback-adjusted. That is, the above links form a self-excited closed-loop oscillation system.

[0055] Therefore, the present invention comprehensively considers the mutual coupling effects of the diesel engine speed control system, the shaft torsional vibration of the diesel generator set mechanical transmission system, the generator and its excitation control system and the grid load system, and establishes a mechanical-electrical-grid coupled torsional vibration analysis model. The basic principle is shown in the attached figure. Figure 4 shown.

[0056] The diesel engine and its speed control system, the generator and its excitation system, and the shaft torsional vibration establish a coupling relationship through the speed signal of the transmission shaft. At the same time, the generator and its excitation system are coupled with the grid load through voltage and current signals, ultimately forming a machine-electricity-grid coupled torsional vibration analysis model. This model can be used to analyze the steady-state characteristics of the shaft torsional vibration under steady-state conditions such as no-load operation and loaded operation, providing support for the design and optimization of related system parameters.

[0057] Furthermore, in one embodiment, the above method further includes: By adjusting the load of the load system model, the stator current in the generator model is collected, and the stator current is compared with the stator current of the generator in the diesel generator set actually operating under the same load. If the difference does not exceed the maximum threshold, it is determined that the shaft system torsional vibration analysis model is successfully constructed. If the difference exceeds the maximum threshold, it is determined that the shaft system torsional vibration analysis model is unsuccessful, and the control parameters of the speed controller model in the shaft system torsional vibration analysis model and / or the elastic coupling parameters of the flexible shaft system model are updated.

[0058] In this embodiment, based on a preliminarily established model for analyzing the coupled torsional vibration of diesel generator sets in an island system, the transient characteristics of the shafting torsional vibration under the coupled system under typical single-unit operation conditions of the island system diesel generator set can be analyzed. Based on the analysis results, feedback can be provided to adjust the model parameters.

[0059] In a specific embodiment, the continuous sudden load condition of the shaft torsional vibration analysis model is analyzed. Under this condition, the diesel generator set is started at no load, the total simulation time is 75 s, and 50% load L1 (active power) is added at 30 s. kW, reactive power kVar), 25% load L2 is added at 45 s, and 25% load L3 is added at 60 s. The parameters of loads L2 and L3 are kW, kVar. The specific load power setting is as follows Figure 7 As shown. The diesel engine PID controller parameters are .

[0060] The time domain variation diagram of the generator stator A phase current (per unit value) obtained under this working condition is as follows Figure 8 As shown in the figure, after the current values ​​of each stage are converted into real values, the comparison with the test results of the same load test conditions of the actual diesel generator set is shown in Table 1 below.

[0061] Table 1 Test results comparison table

[0062] As can be seen from Table 1, the error between the generator A-phase current simulated by the coupling model established in the present invention and the measured value is within 3%, which verifies the correctness of the coupling model established in the present invention and can be used for subsequent analysis and research.

[0063] The total time history of the diesel engine flywheel end was used as the speed signal extraction location, and the time domain speed C of the diesel engine flywheel end was obtained. The no-load start operation of the diesel generator set was completed within 20 seconds, and the diesel engine speed overshoot was less than 15%. After the L1 load was applied for 30 seconds, the diesel generator set speed suddenly dropped to a minimum of 1486 r / min. After the load was applied, the generator excitation control system and the diesel engine speed control system quickly took effect, and the diesel generator set speed stabilized. During the adjustment process, the speed produced a small overshoot, reaching a maximum of 1503 r / min. The maximum speed fluctuation during the overall loading transient process reached 17 r / min. 12 seconds after the load was applied, the speed regained stability.

[0064] Figure 11 The L2 loading process is shown with Figure 10 The L1 loading process shown is similar, but the stabilization time after loading is longer. Figure 12The L3 loading process is shown, which has the same loading power as the L2 loading process. The speed fluctuation in the loading transient process is larger than that of the L2 loading, and the stabilization time after loading is further prolonged, indicating that loading under higher load has a greater impact on the stable operation of the diesel generator set.

[0065] The instantaneous dynamic torque response results and spectrum results of the coupling and generator shaft during each loading process are shown in Figure 2. Figures 13 to 16 shown.

[0066] from Figure 13 and Figure 15 As can be seen from the figure, the transient coupling and generator shaft dynamic torque responses are the largest when loading with L1. The maximum dynamic torque response at the coupling reaches 2948 Nm, and the transient torque at the generator shaft reaches 2722 Nm, both of which are more than an order of magnitude greater than the corresponding torque responses during steady-state operation. Loading with L2 produces the smallest impact torque at the coupling and generator shaft. Loading with L3 results in the longest duration of transient impact torque.

[0067] from Figure 14 and Figure 16 It can be seen from the spectrum results that the torque spectra at the coupling and generator shaft in each loading process are dominated by low-frequency components.

[0068] From the results in the comprehensive diagram, we can find that the greater the load, the greater the transient impact torque the shaft system is subjected to. Under higher load, the shaft system is subjected to the transient impact torque for a relatively longer time.

[0069] In another specific embodiment, the continuous sudden unloading load condition of the shaft torsional vibration analysis model is analyzed. Under this condition, the diesel generator set is started at no load, the total simulation time is 75 s, 50% load (L2+L3) is added at 30 s, 25% load L2 is suddenly unloaded at 45 s, and 25% load L3 is suddenly unloaded at 60 s. The parameters of loads L2 and L3 are kW, kVar. Based on the time-domain speed results for each unloading process, unloading operations, for the same power load, cause smaller overall speed fluctuations than loading operations. The lower the original load, the shorter the duration of the small speed oscillations caused by unloading operations, and the smaller the amplitude of the speed oscillations.

[0070] During the L2 unloading process, the coupling experienced the highest instantaneous impact torque, reaching 1467 Nm. During L3 unloading, the coupling experienced slightly less instantaneous impact torque than during L2 unloading, and the torque fluctuations also lasted for a shorter period. The generator shaft torque showed the same trend as the coupling, with the L2 unloading process reaching a maximum impact torque of 1350 Nm.

[0071] In another specific embodiment, the single-machine oscillation operating condition of the shaft system torsional vibration analysis model is analyzed. The two aforementioned specific embodiments are both typical operating condition simulations under normal parameters. Considering that when certain parameters in the coupling system are improperly selected, the stable operation of the diesel generator set (especially the operating stability when the operating conditions change) will be greatly challenged, in this embodiment, it is assumed that the control system PID parameters are improperly selected and the continuous sudden load condition setting is adopted. The hazards of the single-machine oscillation operating condition are analyzed by example. Specifically, when the PID parameters are reasonably selected, the relevant response results of the coupling system in the L1 loading process are compared. It can be seen that when the control system PID parameters are improperly selected, the speed fluctuation amplitude of the L1 loading process is aggravated, reaching 20 r / min, which is greater than 17 r / min under the normal parameter condition. The large speed oscillation time increases sharply, and the diesel generator set is still unable to restore a stable operating state for a long time.

[0072] Under the oscillation parameters, the oscillation amplitude of the additional torque of the coupling and the generator shaft does not change much during the L1 loading process, but the low-frequency component of the additional torque increases. For a long time, the additional torque of the elastic coupling and the generator shaft are in a state of low-frequency oscillation, which increases the risk of shaft fatigue loss.

[0073] From the above results, it can be seen that if the parameters of the diesel generator set of the island system ship are not selected correctly, it will cause the shaft system oscillation of the diesel generator set for a long time, which is easy to cause fatigue damage to the shaft system.

[0074] In a second aspect, an embodiment of the present application further provides a torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set, which is modeled using the above-mentioned modeling method of the torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set.

[0075] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0076] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0077] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0078] In the description of the embodiments of the present application, unless otherwise specified, " / " means or. For example, A / B can mean A or B. The "and / or" in the text is merely a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "plurality" means two or more than two.

[0079] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0080] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A modeling method for a single-unit shaft torsional vibration analysis model of a marine diesel generator set, characterized in that: The method comprises: Construct the speed controller model, diesel engine work model, diesel engine torque synthesis model, flexible shaft system model, generator model, excitation system model, and load system model respectively; An electromechanical coupling analysis model is established between the diesel engine speed control system model, diesel engine work model, diesel engine torque synthesis model, and flexible shaft system model based on the transmission shaft speed signal; a power grid coupling analysis model is established between the generator model, excitation system model, and load system model based on voltage and current signals; All models are coupled based on the electromechanical coupling analysis model and the power grid coupling analysis model to obtain the shafting torsional vibration analysis model of the ship diesel generator set single-unit control system and the shafting torsional vibration.

2. The modeling method of the torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The input quantity of the diesel engine work model includes the control current output by the speed controller model, and the output quantity includes the cylinder mean indicated pressure.

3. The modeling method of the torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The input quantity of the diesel engine torque synthesis model includes the cylinder mean indicated pressure output by the diesel engine work model, and the output quantity includes the cylinder mean torque and the cylinder additional torque.

4. The modeling method of the torsional vibration analysis model of a single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The input quantity of the generator model includes the voltage and current signals output by the load system model and the excitation system model, and the output quantity includes the electromagnetic torque.

5. The modeling method of the torsional vibration analysis model of the single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The input quantity of the flexible shafting model includes the cylinder average torque and cylinder additional torque output by the diesel engine work model, and the electromagnetic torque output by the generator model, and the output quantity includes the transmission shaft speed signal.

6. The modeling method of the torsional vibration analysis model of the single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The excitation system model adopts a phase compound excitation brushless excitation control model.

7. The modeling method of the torsional vibration analysis model of the single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The load system model adopts a static load model.

8. The modeling method of the torsional vibration analysis model of the single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The method further comprises: By adjusting the load of the load system model, the stator current in the generator model is collected, and the stator current is compared with the stator current of the generator in the diesel generator set actually operating under the same load. If the difference does not exceed the maximum threshold, it is determined that the shaft system torsional vibration analysis model is successfully constructed. If the difference exceeds the maximum threshold, it is determined that the shaft system torsional vibration analysis model is unsuccessful, and the control parameters of the speed controller model in the shaft system torsional vibration analysis model and / or the elastic coupling parameters of the flexible shaft system model are updated.

9. The modeling method of the torsional vibration analysis model of the single-unit shaft system of a marine diesel generator set according to claim 1 is characterized in that: The method further comprises: By adjusting the load of the load system model, the drive shaft speed signal is collected and compared with the drive shaft speed signal of the diesel generator set actually operating under the same load. If the difference does not exceed the maximum threshold, it is determined that the shaft system torsional vibration analysis model is successfully constructed. If the difference exceeds the maximum threshold, it is determined that the shaft system torsional vibration analysis model is unsuccessful, and the control parameters of the speed controller model in the shaft system torsional vibration analysis model and / or the elastic coupling parameters of the flexible shaft system model are updated.

10. A single-unit shaft torsional vibration analysis model for a marine diesel generator set, characterized in that: The model is obtained by adopting the modeling method of the single-machine shaft system torsional vibration analysis model of the marine diesel generator set according to any one of claims 1 to 9.

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