Design method of front-end speed-regulating wind turbine transmission chain based on hydraulic torque converter

Abstract

The application provides a design method of a front-end speed regulation type wind turbine generator set transmission chain based on a hydraulic torque converter, comprising the following steps: based on a planetary gear train configuration and a power flow distribution mode, a hydraulic speed regulation mechanism is configured; according to the configuration of the selected hydraulic speed regulation mechanism, an improved genetic algorithm is used to define an optimization target, the optimization target comprising maximizing a speed regulation ratio, maximizing a comprehensive efficiency at a rated working condition and maximizing an average comprehensive efficiency in a working range; an optimization constraint condition is established, the optimization constraint condition comprising a hydraulic characteristic constraint and an output rotating speed constraint; according to the optimization target and the optimization constraint condition, an optimization process is performed through the improved genetic algorithm to obtain an optimal solution of the ratio of the gear teeth of the first and second planetary gear sets to the gear teeth of the sun gear. The application can solve the technical problem that the speed ratio distribution of the transmission system and the characteristics of the hydraulic torque converter are not optimized in the prior art, so that the overall performance of the transmission chain is difficult to reach the optimum.

Description

Technical Field

[0001] This invention relates to the field of wind turbine generator transmission system design technology, specifically to a design method for a front-end speed-regulating wind turbine transmission chain based on a hydraulic torque converter. Background Technology

[0002] As wind turbine generators develop towards higher power outputs, mainstream variable-speed constant-frequency wind turbine generators increasingly rely on high-power converters such as rectifiers, inverters, and converters. These devices are becoming increasingly expensive, their control systems more complex, and they have high energy consumption and heat dissipation requirements. Furthermore, they inject harmonics into the grid, harming power quality. To fundamentally solve these problems, the technology of using a hydraulic torque converter-based speed-regulating transmission mechanism shows great potential. This technology converts the changing rotor speed into a constant speed through a hydraulic speed-regulating mechanism, driving a synchronous generator directly to the grid, thus eliminating the need for a complex frequency converter. Currently, the design of the transmission chain configuration for front-end speed-regulating wind turbine generators based on hydraulic torque converters faces the following challenges: Insufficient configuration design and parameter optimization; the front-end speed regulation configuration design still lacks a systematic and integrated optimization concept; and existing design methods mostly rely on empirical parameters and iterative trial and error, failing to coordinate the optimization of the speed ratio distribution of the transmission system and the characteristics of the hydraulic torque converter, resulting in the overall performance of the transmission chain being difficult to achieve optimal results. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a design method for the transmission chain of a front-end speed-regulating wind turbine based on a hydraulic torque converter. This method solves the technical problem in existing technologies where the speed ratio distribution of the transmission system and the characteristics of the hydraulic torque converter are not optimized in a coordinated manner, resulting in the overall performance of the transmission chain being difficult to achieve optimal performance.

[0004] The technical solution adopted in this invention is as follows: Firstly, a design method for a front-end speed-regulating wind turbine drive train based on a hydraulic torque converter is provided, including the following steps: Based on the planetary gear train configuration and power flow distribution method, the configuration of the hydraulic speed regulating mechanism is selected; Based on the selected configuration of the hydraulic speed regulating mechanism, an improved genetic algorithm is used to find the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear.

[0005] In conjunction with the first aspect, in some alternative embodiments, the hydraulic speed regulating mechanism includes a two-stage planetary gear and a hydraulic torque converter, with the two-stage planetary gear located after the speed-increasing gearbox and before the generator.

[0006] In conjunction with the first aspect, in some alternative implementations, the configuration of the hydraulic speed regulating mechanism is selected based on the planetary gear train configuration and power flow distribution method, including: Select the planetary gear train configuration based on the basic transmission ratio, and determine the connection relationship between the planet carrier, external gear ring, sun gear, and hydraulic speed regulating mechanism; Based on the selected planetary gear train configuration, the dynamic transmission ratios of the split-flow and return-flow configurations in the mechanical-hydraulic hybrid speed regulation configuration are calculated respectively. The mechanical-hydraulic hybrid speed regulation configuration with a larger dynamic transmission ratio is selected as the configuration of the hydraulic speed regulation mechanism.

[0007] In conjunction with the first aspect, in some optional embodiments, the planetary gear train is configured as a CRS configuration, with the planet carrier as the input, the sun gear as the output, and the external gear ring connected to the hydraulic speed regulating mechanism.

[0008] In conjunction with the first aspect, in some alternative embodiments, the hydraulic speed regulating mechanism is configured as a reflux configuration, in which the second-stage planetary carrier is fixed, and the output of the first-stage sun gear is fed back to the first-stage ring gear and coupled to the first-stage planetary carrier through the hydraulic torque converter and the second-stage planetary gear train.

[0009] In conjunction with the first aspect, in some alternative implementations, based on the selected configuration of the hydraulic speed regulating mechanism, an improved genetic algorithm is used to find the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear, including: Define optimization objectives, including maximizing the speed regulation ratio, maximizing the overall efficiency under rated operating conditions, and maximizing the average overall efficiency over the operating range. Establish optimization constraints, which include hydraulic characteristic constraints and output speed constraints; Based on the optimization objective and constraints, an improved genetic algorithm is used to perform the optimization process and obtain the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear.

[0010] In conjunction with the first aspect, in some optional implementations, the hydraulic characteristic constraint is: the stall torque ratio of the guide vane adjustable hydraulic torque converter. Output speed constraint of hydraulic speed regulating mechanism: .

[0011] In conjunction with the first aspect, in some alternative implementations, the improved genetic algorithm is the second-generation NSGA algorithm.

[0012] Secondly, a front-end speed-regulating wind turbine drive train is provided, which is designed using the front-end speed-regulating wind turbine drive train design method for hydraulic torque converters as described in the first aspect.

[0013] In some alternative embodiments, the drive shaft is made of 40CrMo4 alloy steel, and the gear is made of 18CrNiMo7-6 carburized steel. The planetary gear bearings are selected from single-row or double-row cylindrical roller bearings, including SKF NCF3080CV or Koyo NU3352; The planetary carrier shaft uses tapered roller bearings, including TIMKENEE277455-277565 or SKFEE655270 / 655345.

[0014] As can be seen from the above technical solution, the beneficial technical effects of the present invention are as follows: By combining genetic algorithms and mathematical simulations, and through optimizing power splitting strategies, multi-parameter collaborative design, and material and bearing selection for key components, high efficiency, compactness, high reliability, and excellent dynamic speed regulation performance of the transmission chain can be achieved. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0016] Figure 1 This is a schematic diagram of the design method for the transmission chain of a front-end speed-regulating wind turbine based on a hydraulic torque converter in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structural connections of various planetary gear train configurations in the embodiments of the present invention; Figure 3 This is a power flow diagram of the split-flow and recirculation configurations in an embodiment of the present invention; Figure 4 This is a schematic diagram of the hydraulic speed regulating mechanism in an embodiment of the present invention; Figure 5 As described in the embodiments of the present invention change, Performance curves of the hydraulic torque converter when the load remains constant; Figure 6 As described in the embodiments of the present invention change, Comparison of hydraulic torque converter performance when constant; Figure 7 As described in the embodiments of the present invention constant, Performance curves of hydraulic torque converter under varying conditions; Figure 8 As described in the embodiments of the present invention constant, Comparison chart of hydraulic torque converter performance under varying conditions; Figure 9 As described in the embodiments of the present invention , The optimal solution analysis diagram is shown. Detailed Implementation

[0017] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0018] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0019] Example This embodiment provides a design method for the transmission chain of a front-end speed-regulating wind turbine based on a hydraulic torque converter. This method constructs a multi-physics parameter synergistic optimization relationship between the hydraulic torque converter and the planetary gear transmission, deeply considering the comprehensive impact of power splitting path design on the overall gearbox structure (such as volume, weight, and compactness) and the lifespan of key components (such as bearings and gear fatigue strength). Simultaneously, it also takes into account the complex nonlinear coupling effect between the hydraulic torque converter and the mechanical transmission, fully quantifying and utilizing it during the configuration design and gear geometry analysis stages.

[0020] Step 1: Select the configuration of the hydraulic speed regulating mechanism based on the planetary gear train configuration and power flow distribution method. Step 11: Select the planetary gear train configuration based on the basic transmission ratio, and determine the connection relationship between the planet carrier, external gear ring, sun gear, and hydraulic speed regulating mechanism. A planetary gear train is a planetary gear system consisting of a sun gear, planetary gears, a planet carrier, and an external ring gear. The planetary gears revolve around the central sun gear while simultaneously rotating on their own axes; this combined motion is constrained and transmitted through the planet carrier. The planetary gear train achieves power input, output, splitting, and merging functions through three ports: the sun gear, the planet carrier, and the ring gear. It boasts advantages such as coaxial layout, compact structure, and high power density. Planetary gear trains can flexibly implement various functions such as deceleration, acceleration, differential speed control, and motion synthesis and decomposition. In the wind turbine transmission chain of the front-end speed regulation method based on a hydraulic torque converter in this application, a two-stage planetary gear train is used to achieve the speed regulation function.

[0021] In a specific implementation, the hydraulic speed regulating mechanism is defined as a combination of a two-stage planetary gear set and a hydraulic torque converter. The two-stage planetary gear set is located after the speed-increasing gearbox and before the generator. The components connected to the hydraulic speed regulating mechanism are considered fixed, and the basic transmission ratio of the planetary gear train is first calculated. The hybrid transmission ratio of mechanical-hydraulic speed regulation is based on the speed variation of the basic transmission ratio; therefore, the basic transmission ratios of various configurations can be compared to determine the planetary gear train configuration design. Specific configurations and basic transmission ratios are as follows: Figure 1 As shown. Figure 2In the diagram, C represents the planetary carrier, R represents the external gear ring, and S represents the sun gear. The names are arranged in the order of input components, components connected to the hydraulic torque converter, and output components.

[0022] To improve the overall transmission ratio of the drivetrain, reduce its length, total mass, volume, and manufacturing cost, the gear transmission in wind turbine drives should be a speed-increasing structure. SRC, SCR, and RSC structures are speed-reducing structures and are not suitable for front-end speed-regulating wind turbines. Among the three speed-increasing structures, the CRS structure has the largest transmission ratio, achieving the largest transmission ratio and speed regulation range. Furthermore, its planetary carrier input and sun gear output structure is similar to the traditional wind turbine planetary gear train structure, resulting in lower manufacturing costs. Its layout and geometric parameter design can follow existing engineering experience in wind turbine planetary gear transmissions. Therefore, this application selects the CRS configuration as the speed-regulating planetary gear train configuration, i.e., planetary carrier input, sun gear output, and external gear ring connected to the hydraulic speed regulation mechanism.

[0023] Based on the planetary gear train speed characteristic equation (1), the speed relationship of each component of the planetary gear train is shown in equation (2): (1) (2) and (3) in, For the transmission ratio between the sun gear and the ring gear in the planet carrier reference frame, For the rotational speed of the sun gear in the planetary frame reference system, The rotational speed of the sun gear in the planetary carrier reference frame For the rotational speed of the sun gear, For gear ring speed, For planetary carrier speed, For the number of teeth of the sun gear, For the number of teeth on the gear ring, It is the ratio of the number of teeth on the external gear ring to the number of teeth on the sun gear.

[0024] Taking the direction of the sun gear's rotation as the direction, in order to achieve a larger dynamic transmission ratio, the hydraulic speed regulating mechanism should drive the external gear ring to reverse, that is... ;have: When input speed When the pressure is reduced, the guide vane opening of the hydraulic torque converter increases, driving... Increase, thereby maintain Unchanged; when the input speed remains unchanged. When the opening of the hydraulic torque converter guide vanes decreases as the torque converter increases, the drive... Decrease, thereby maintain Unchanged. Those skilled in the art should understand that the rated frequency of my country's power grid is 50Hz; therefore, doubly-fed asynchronous wind turbine generators connected to my country's power grid need to meet the 50Hz grid connection requirement. When using a commonly used four-pole generator, its synchronous speed is 1500 r / min.

[0025] Step 12: Based on the selected planetary gear train configuration, calculate the dynamic transmission ratio of the split-flow and return-flow configurations in the mechanical-hydraulic hybrid speed regulation configuration, and select the mechanical-hydraulic hybrid speed regulation configuration with the larger dynamic transmission ratio as the configuration of the hydraulic speed regulation mechanism. In mechanical-hydraulic hybrid speed regulation configurations, based on the energy flow pattern, there are two types: The power flow direction of the hydraulic system is the same as the main flow direction, and the energy flows back after being split, which is called a split-flow type; the power flow direction of the hydraulic system is opposite to the main flow direction, and the energy flows back after being split, forming a power cycle, which is called a return-flow type. The power flow diagrams for split-flow and return-flow types are shown below. Figure 3 As shown. Those skilled in the art will understand that the input speed... growth rate The dynamic transmission ratio is a constant value. Given that the parameters of the speed-increasing gearbox and the differential gearbox, as well as the performance of the torque converter, are determined, only the input speed remains as an unknown. Therefore, a range can be calculated, which is the speed regulation range. After calculation, the configuration with the larger speed regulation range is selected.

[0026] Calculate the dynamic transmission ratio of the two speed regulating mechanisms. Let the ratio of the number of teeth on the external ring gear to the number of teeth on the sun gear of the speed regulating planetary gear train be... The turbine speed of the hydraulic torque converter is Pump impeller speed is The ratio of turbine speed to pump impeller speed is The gear transmission ratio after the pump wheel output is: .

[0027] For a split-flow type, the entire hydraulic speed regulating mechanism needs to maintain... The output target, according to the planetary gear train speed formula (3), is:

[0028] The external gear ring is connected to the hydraulic speed regulating mechanism as follows:

[0029] From the characteristics of the hydraulic torque converter:

[0030] The power is split between the hydraulic torque converter and the planetary gear set and planetary carrier, and is connected to the output shaft of the main gearbox. Therefore:

[0031] Combining the above equations, we have:

[0032] Dynamic transmission ratio of split-flow configuration for:

[0033] For the reflux type, the hydraulic torque converter is connected to the output shaft of the sun gear of the planetary gear train, and the power is split with that of the magnetic motor. The pump wheel speed is the same as the output speed of the sun gear, and the entire hydraulic speed regulating mechanism also needs to maintain this speed. The output targets are:

[0034] According to the planetary gear train speed formula (3), we have:

[0035] The external gear ring is connected to the turbine of the hydraulic torque converter as follows:

[0036] From the characteristics of the hydraulic torque converter:

[0037] Combining the above equations, we have:

[0038] Dynamic transmission ratio of the recirculation configuration for:

[0039] Comparing the dynamic transmission ratios of the two configurations reveals that when the guide vanes of the hydraulic torque converter are adjusted... At the same time, the recirculation type can change a wider range of dynamic transmission ratios and a wider speed regulation range. Therefore, the recirculation type configuration is adopted in this application. The structural schematic diagram of the hydraulic speed regulation mechanism is shown in the figure below. Figure 4 As shown.

[0040] Based on the above analysis of configuration options, the specific structure of the front-end speed-regulating wind turbine drive train based on a hydraulic torque converter proposed in this application is as follows: The main mechanical components of the transmission chain include a wind turbine, main shaft, speed-increasing gearbox and generator connected in sequence, as well as a hydraulic speed regulating mechanism connected in series on the side of the speed-increasing gearbox. The hydraulic speed regulating mechanism is composed of a two-stage planetary gear and a hydraulic torque converter, which is designed to achieve high speed ratio regulation and provide a connection point for power splitting.

[0041] Specifically, for the recirculation configuration, an adjustable hydraulic torque converter is introduced inside the planetary gearbox to form a power splitting path. This hydraulic torque converter is preferably an adjustable torque converter with guide vanes to provide flexible speed regulation and torque conversion capabilities. For the mechanical branch: most of the power input from the wind turbine through the main shaft (carrying more than 80% of the total transmission power) is directly transmitted to the generator through the planetary gears. The design of this branch should focus on high efficiency and high load capacity. For the hydraulic branch: a moving component in the planetary gear train (e.g., the sun gear or planet gear of the first-stage planetary gear) draws out the remaining power (carrying less than 20% of the total transmission power) as the pump wheel input of the hydraulic torque converter. After transmission, speed regulation, and torque conversion by the hydraulic torque converter, the power output from its turbine is fed back to another moving component of the planetary gear system (e.g., the second-stage ring gear or planet carrier), forming a closed-loop power circulation branch.

[0042] In some embodiments, the hydraulic speed regulating mechanism is preferably configured as follows: a recirculation configuration is adopted, in which the second-stage planetary carrier is fixed, and the output of the first-stage sun gear is fed back to the first-stage ring gear and coupled to the first-stage planetary carrier through the hydraulic torque converter and the second-stage planetary gear train, thereby achieving flexible power circulation. This design can effectively disperse impact loads and provide additional speed regulation freedom. This power splitting scheme brings significant multiple advantages: 1. Improve overall transmission efficiency and reduce energy loss: Mechanical transmission circuits (gear drives) inherently possess extremely high transmission efficiency (typically above 98%), while hydraulic torque converters, although exhibiting excellent flexible speed regulation and torsional vibration suppression capabilities, still experience some hydraulic losses during torque conversion and speed regulation (efficiency typically between 80% and 90%). By allowing most of the power (over 80%) to be transmitted through the high-efficiency mechanical circuits, while only a small portion (less than 20%) flows through the hydraulic speed regulation circuits, the impact of the hydraulic speed regulation mechanism on overall transmission efficiency is significantly reduced, thereby substantially decreasing the system's total power loss and improving the economic efficiency of the wind turbine.

[0043] 2. Reduced load requirements and cost of the hydraulic speed regulation branch: Limiting the power carried by the hydraulic speed regulation branch to a small portion (less than 20%) of the total power directly and significantly reduces the power load requirements of the hydraulic torque converter itself. Lower power requirements mean a smaller size for the hydraulic torque converter. There's no need to design a large hydraulic torque converter capable of transmitting all the power, allowing for a smaller and more compact design. This reduces the manufacturing cost of the hydraulic torque converter; while maintaining performance, smaller torque converters significantly control material consumption, processing difficulty, and manufacturing costs. It also reduces the burden on other components of the hydraulic speed regulation branch: the load-bearing capacity and size requirements of planetary gear train components, pumps, cooling systems, etc., connected to the hydraulic torque converter are also reduced, further saving overall system cost and weight.

[0044] 3. Optimize system dynamic response and stability: Although the hydraulic branch only transmits a small portion of the power, its inherent flexible speed regulation and torsional vibration filtering characteristics are sufficient to positively influence the dynamic behavior of the entire transmission chain. It can effectively absorb the random wind load impact on the input side of the wind turbine and the disturbance on the power grid side, acting as a "shock absorber" for the main mechanical branch, while avoiding the thermal management pressure and excessive energy loss that might result from all power passing through the hydraulic device.

[0045] Step 2: Based on the selected configuration of the hydraulic speed regulating mechanism, use an improved genetic algorithm to find the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear. Those skilled in the art will understand that, after the configuration has been determined according to the method in step 1, the foregoing description... This still represents the ratio of the number of teeth on the ring gear to the number of teeth on the sun gear in the speed-regulating planetary gear train. Specifically, it corresponds to the ratio of the number of teeth on the first-stage planetary gear ring to the number of teeth on the sun gear. The gear transmission ratio after the pump wheel output is... This is essentially equivalent to the ratio of the number of teeth on the second-stage planetary gear ring to the number of teeth on the sun gear; in the following analysis, the definition is... , These represent the ratios of the number of teeth on the first and second stage planetary gear rings to the number of teeth on the sun gear.

[0046] The inventors of this application discovered through research that , These are important parameters in the design of hydraulic speed regulating mechanisms. The key to designing a hydraulic speed regulating mechanism lies in finding the optimal parameters. , The specific research and analysis process is as follows: Assuming the input speed direction is positive, the speed relationships of the components of the first and second stage planetary gear sets in the hydraulic speed regulating mechanism should satisfy:

[0047]

[0048] In the formula, , These are the ratios of the number of teeth on the first and second stage planetary gear sets to the number of teeth on the sun gear, respectively. , These are the rotational speeds of the planetary carriers for the first and second stage planetary sets, respectively, in rpm. , These are the rotational speeds of the first and second stage planetary gear rings, respectively, in rpm; , These are the rotational speeds of the sun gears of the first and second planetary arrays, respectively, in rpm; Because the two-stage planetary gear rings are directly connected, therefore:

[0049] The second-stage planetary carrier is fixed, and includes:

[0050] The first-stage planetary gear train's sun gear is connected to the output shaft, which in turn is connected to a synchronous generator. The output shaft is also connected to a guide vane adjustable hydraulic torque converter, so all three operate at the same speed.

[0051] In the above formula, The pump wheel speed, This refers to the synchronous generator speed.

[0052] The turbine output of the guide vane adjustable hydraulic torque converter is connected to the sun gear of the second-stage planetary gear set, and has the following characteristics:

[0053] In the above formula, This refers to the turbine speed of the hydraulic torque converter.

[0054] By combining the above calculation formulas, the synchronous generator speed can be derived. Input speed with hydraulic speed regulating mechanism Turbine speed of guide vane adjustable hydraulic torque converter The matching relationships are as follows:

[0055] Turbine speed of guide vane adjustable hydraulic torque converter for:

[0056] Pump impeller to turbine speed ratio of the guide vane adjustable hydraulic torque converter for:

[0057] In the formula, the transmission ratio between the output and input of the hydraulic speed regulating mechanism ; The input speed range of the hydraulic speed regulating mechanism is:

[0058] The theoretical speed regulation range is obtained as follows:

[0059] In reality, the actual speed regulation range will be smaller due to the power loss caused by the characteristics of the hydraulic torque converter, the power loss of gear transmission, and the influence of motor load.

[0060] Neglecting frictional losses in gear transmission, the torque relationships of the components of the first and second stage planetary gear sets should satisfy:

[0061] In the formula , The torque of the planet carrier for the first and second rows of planetary gears is given in units of [missing information]. ; , The torque of the first and second gear rings is expressed in units of [missing information]. ; , The torque of the sun gear carrier for the first and second rows of planets is given in units of... ; Based on the connection relationships of each component, we can conclude that:

[0062] In the formula The torque of the hydraulic torque converter pump wheel is expressed in units of... ; The torque of the hydraulic torque converter turbine is expressed in units of... ; The output torque of the hydraulic speed regulating mechanism, i.e., the synchronous motor torque, is expressed in units of... ; The output torque can be obtained from the above formula. With turbine torque and pump wheel torque Matching relationship:

[0063] Assume the torque ratio of the guide vane adjustable hydraulic torque converter is... :

[0064] The ratio of absorbed power to input power of the hydraulic torque converter can be calculated using the above formula. :

[0065] Overall efficiency of hydraulic speed regulating mechanism The calculation method is as follows:

[0066] Based on the above analysis, it can be seen that , Parameters affect the speed ratio of the hydraulic speed regulating mechanism hydraulic torque converter efficiency Power ratio of hydraulic torque converter Overall efficiency of hydraulic speed regulating mechanism .

[0067] Hydraulic torque converter efficiency = turbine power / pump impeller power = turbine torque Speed / Pump impeller torque Rotational speed can be obtained through CFD simulation.

[0068] To optimize the design of the hydraulic speed regulating mechanism, identify... , The optimal solution was found in this embodiment. A numerical analysis model of the hydraulic speed regulating mechanism was built using Matlab software to discuss how to maintain the output speed of the synchronous generator under different input speeds. Unchanged, Different , Impact on the performance of the speed regulating mechanism: Those skilled in the art should understand that, for wind turbine generator sets, the transmission ratio of planetary gear trains with fixed planetary carriers is typically 3-6; here, 4 is used as an example: when When unchanged, different The impact on the performance of hydraulic speed regulating mechanisms, such as Figure 5 , Figure 6 As shown, it can be observed that when fixed, As the hydraulic speed regulating mechanism increases, its speed range increases, its power ratio increases, its average efficiency decreases, and its maximum efficiency decreases. Figure 5 , 6 All of these points are based on simulations to maintain the output speed. The point cannot be maintained at 1500. The input was omitted and was not displayed.

[0069] All points in the graph represent those that can maintain an output of 1500 RPM based on simulation results; inputs that cannot maintain 1500 RPM have been discarded. The x-axis range in the graph primarily displays these curves. when When unchanged, different The impact on the performance of hydraulic speed regulating mechanisms, such as Figure 7 , Figure 8 As shown, it can be observed that when fixed, As the efficiency increases, the speed range of the hydraulic speed regulating mechanism decreases, the average efficiency increases, and the maximum efficiency increases. Figure 7 , 8 All of these points are based on simulations to maintain the output speed. The point cannot be maintained at 1500. The input was omitted and was not displayed.

[0070] The above analysis shows that the speed regulation range and efficiency of a hydraulic speed regulating mechanism are negatively correlated. Therefore, designing a hydraulic speed regulating mechanism requires finding a set of speed regulation ranges that are as large as possible while maximizing efficiency. , Parameters. In this implementation, a genetic algorithm is used to... , The parameters are optimized through multi-objective optimization to find the optimal design parameters. The specific steps are as follows: Step 21: Define optimization objectives, including maximizing the speed regulation ratio, maximizing the overall efficiency under rated operating conditions, and maximizing the average overall efficiency over the operating range. Maximizing the speed regulation ratio, the speed regulation range of the hydraulic speed regulation mechanism determines the operating range and stability of the front-end speed-regulating wind turbine unit. Speed ​​regulation ratio When the input speed of the hydraulic speed regulating mechanism is... At the same time, the hydraulic speed regulating mechanism can stably output the speed. The higher the speed ratio, the better.

[0071] The overall efficiency of the hydraulic speed control mechanism under rated operating conditions refers to the maximum efficiency that the hydraulic speed control mechanism can achieve within its operating speed range. When designing a front-end speed-regulating wind turbine, this input speed is designed to be the rated operating condition.

[0072] Maximizing the average overall efficiency within the working range is the goal of the hydraulic speed regulating mechanism at the input speed. The average efficiency within the system reflects the average efficiency that the hydraulic speed regulating mechanism can achieve when the input speed of the wind turbine fluctuates.

[0073] Step 22: Establish optimization constraints, including hydraulic characteristic constraints and output speed constraints. During the optimization process, the following engineering and theoretical constraints must be met to ensure the practicality and reliability of the solution: Hydraulic characteristic constraints: The characteristics of the guide vane adjustable hydraulic torque converter must meet the stall torque ratio requirement. This ensures the system's ability to start and regulate speed under low-speed, high-torque conditions.

[0074] Output speed constraint: The output speed of the hydraulic speed regulating mechanism should be maintained at... Ensure that the synchronous generator operates at a frequency of 50Hz to avoid impacting the power grid.

[0075] Step 23: Based on the optimization objective and constraints, execute the optimization process using an improved genetic algorithm to obtain the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear. In this embodiment, an improved second-generation NSGA algorithm is employed. This algorithm is a global optimization algorithm based on the principles of biological natural selection and genetics, and is optimized for multi-objective nonlinear optimization problems. Its basic idea is to encode a set of solutions to the problem and represent them as chromosomes, establishing a population composed of a set of chromosomes. Through genetic operations such as selection, crossover, and mutation, the population is continuously evolved to find the optimal solution. The specific solution process is as follows: The first step is to initialize the population. Population Setup: The population size is set to 100 individuals, with each individual representing a combination of design variables. Variable Encoding: Design variables are encoded using real-number encoding with a precision of 0.001. Initial Population Generation: Based on the sample range specified by the constraints, the initial population is generated using a standardized Latin hypercube. The sampling method generates the initial population, ensuring that the initial samples are evenly distributed within the design space.

[0076] Algorithm parameters: The maximum number of generations T is set to 3000, the crossover probability Pc is set to 0.85, and the mutation probability Pm is set to 0.1.

[0077] In some implementations, the speed regulation ratio weight is set to 0.2, the maximum efficiency weight is set to 0.5, and the average efficiency weight is set to 0.3.

[0078] Step 2: Adaptive Non-Dominated Sort Constraint handling: An external penalty function is introduced to calculate the constraint violation degree (CV value) of individuals in the population, and individuals that violate the constraints are penalized. in, The degree of constraint violation for individual samples in the population. For inequality constraints, As an equality constraint, the penalty factor is dynamically adjusted during the optimization process, with an initial value set to 100.

[0079] Sorting Criteria: Sorting is based on the Deb individual comparison criterion. The basic principle is to determine the dominance relationship between individual solution sets according to three priorities from largest to smallest: the size of the objective function of feasible solution sets, the feasibility of the solution sets, and the degree of constraint violation of infeasible solution sets. Feasible solutions are selected first; if all are feasible, the objective function values ​​are compared; if all are infeasible, the constraint violation degrees are compared. This ensures the convergence of the algorithm and its ability to find effective solutions.

[0080] Step 3: Crowding Calculation Calculate the crowding distance for each individual in the non-dominated layer. A larger crowding distance is more conducive to population growth. The distribution of diversity naturally leads to a better solution set in the corresponding Pareto layer.

[0081]

[0082] in, Let M represent the crowding level of an individual, and M be the number of objective functions. They were respectively in the second On the objective function, the first The individual and the first The target value corresponding to each individual These are the maximum and minimum objective values ​​for all individuals on the k-th objective function, respectively.

[0083] Step 4: Selection and Reproduction A tournament selection mechanism (tournament size k=5) is used to select individuals with high fitness from the initial population. The superior individuals with large crowding distances are used as the parent population. Given that the design parameters are encoded using real numbers, the parent population generates the offspring population by simulating binary crossover (SBX) and polynomial mutation operators.

[0084] Step 5: Elite Retention Strategy The parent and offspring populations are merged to form a larger new population. The new population is then re-sorted for non-dominated order and crowding density is calculated. Based on the sorting results and crowding distance, the top N optimal individuals (N is the population size) are selected to form the next generation population, ensuring that superior individuals are inherited.

[0085] Step 6: Convergence Judgment The optimization terminates when the Pareto front no longer changes significantly over multiple generations (e.g., the average rate of change of the objective function value is less than 0.01) or when the maximum number of generations is reached. In this implementation, the number of population iterations is set to 3000 generations, and it has been verified that the objective function value converges at this number of iterations.

[0086] After optimization through the above steps, the algorithm terminates, outputting a set of non-dominated solutions located on the Pareto front. These solutions represent the best-performing parameter combinations given the objective and constraints. The entire optimization process and the output best-performing parameters are as follows: Figure 9 As shown, the final parameter combination is selected. , At this time, the operating input speed range is: The speed regulation ratio is 1.5547; the hydraulic speed regulation mechanism has a maximum efficiency of 93.04% and an average efficiency of 83.05%.

[0087] In some embodiments, for the designed hydraulic speed regulating mechanism, material selection and bearing selection can be performed on key components of the transmission system to ensure that its strength, stiffness, fatigue life, and reliability meet the design requirements, as follows: Driveshaft Material Selection: Based on the theoretical operating speed, rated input power, and stress conditions of each stage of the driveshaft, high-strength and high-toughness alloy steel is selected as the driveshaft material. 40CrMo4 alloy steel is preferred as the material for each stage of the driveshaft, and a quenching and tempering heat treatment method is adopted. This material has excellent comprehensive mechanical properties and good hardenability, meeting the load-bearing requirements of medium and high power driveshafts. Its elastic modulus is 206 GPa, Poisson's ratio is 0.3, and density is 7850 kg / m³. 3 .

[0088] Gear Material Selection: Key gear components such as planetary gears and sun gears within the speed-increasing gearbox and hydraulic speed-regulating mechanism bear high loads and impacts, requiring materials with high strength, high wear resistance, and good pitting corrosion resistance. 18CrNiMo7-6 carburized steel is the preferred gear material. After carburizing and quenching, this material achieves a surface hardness of HRC58-62 while maintaining good internal toughness, effectively resisting fatigue damage and wear.

[0089] Bearing selection and arrangement: Based on the stress conditions (radial load, axial load), speed, installation space and expected life of each bearing position in the transmission system, a precise bearing selection and optimized arrangement are carried out.

[0090] Gearbox internal bearings: Selection depends on the gearbox type and load. For example, angular contact ball bearings can be used for high-speed shafts, while tapered roller bearings can be used for low-speed shafts. Planetary gear bearings are typically single-row or double-row cylindrical roller bearings, such as SKF NCF3080CV or Koyo NU3352, to bear the main radial loads. Planetary carrier shafts typically use tapered roller bearings, such as TIMKENEE277455-277565 or SKFEE655270. / 655345, to withstand both radial and axial loads simultaneously and provide good stiffness.

[0091] The transmission chain design method for front-end speed-regulating wind turbines provided in this embodiment is based on a combination of genetic algorithms and mathematical simulations. By optimizing power splitting strategies, multi-parameter collaborative design, and material and bearing selection for key components, it can achieve high efficiency, compactness, high reliability, and excellent dynamic speed regulation performance of the transmission chain.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for designing a drive train for a front-end speed-regulating wind turbine based on a hydraulic torque converter, characterized in that, Includes the following steps: Based on the planetary gear train configuration and power flow distribution method, the configuration of the hydraulic speed regulating mechanism is selected; Based on the selected configuration of the hydraulic speed regulating mechanism, an improved genetic algorithm is used to find the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear.

2. The method for designing a front-end speed-regulating wind turbine drive train based on a hydraulic torque converter according to claim 1, characterized in that, The hydraulic speed regulating mechanism includes a two-stage planetary gear and a hydraulic torque converter. The two-stage planetary gear is located after the speed-increasing gearbox and before the generator.

3. The method for designing a front-end speed-regulating wind turbine drive train based on a hydraulic torque converter according to claim 1, characterized in that, Based on the planetary gear train configuration and power flow distribution method, the configuration selection of the hydraulic speed regulating mechanism is carried out, including: Select the planetary gear train configuration based on the basic transmission ratio, and determine the connection relationship between the planet carrier, external gear ring, sun gear, and hydraulic speed regulating mechanism; Based on the selected planetary gear train configuration, the dynamic transmission ratios of the split-flow and return-flow configurations in the mechanical-hydraulic hybrid speed regulation configuration are calculated respectively. The mechanical-hydraulic hybrid speed regulation configuration with a larger dynamic transmission ratio is selected as the configuration of the hydraulic speed regulation mechanism.

4. The method for designing a front-end speed-regulating wind turbine transmission chain based on a hydraulic torque converter according to claim 3, characterized in that, The planetary gear train has a CRS configuration, with the planet carrier as the input, the sun gear as the output, and the external gear ring connected to the hydraulic speed regulating mechanism.

5. The method for designing a front-end speed-regulating wind turbine drive train based on a hydraulic torque converter according to claim 3, characterized in that, The hydraulic speed regulating mechanism has a reflux configuration, which fixes the second-stage planetary carrier and feeds the output of the first-stage sun gear back to the first-stage ring gear through the hydraulic torque converter and the second-stage planetary gear train, and couples with the first-stage planetary carrier.

6. The design method for the transmission chain of a front-end speed-regulating wind turbine based on a hydraulic torque converter according to claim 1, characterized in that, Based on the selected configuration of the hydraulic speed regulating mechanism, an improved genetic algorithm is used to find the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear, including: Define optimization objectives, including maximizing the speed regulation ratio, maximizing the overall efficiency under rated operating conditions, and maximizing the average overall efficiency over the operating range. Establish optimization constraints, which include hydraulic characteristic constraints and output speed constraints; Based on the optimization objective and constraints, an improved genetic algorithm is used to perform the optimization process and obtain the optimal solution for the ratio of the number of teeth of the first-stage and second-stage planetary gear rings to the number of teeth of the sun gear.

7. The design method for the transmission chain of a front-end speed-regulating wind turbine based on a hydraulic torque converter according to claim 6, characterized in that, The hydraulic characteristic constraint is: the stall torque ratio of the guide vane adjustable hydraulic torque converter. Output speed constraint of hydraulic speed regulating mechanism: .

8. The design method for the transmission chain of a front-end speed-regulating wind turbine based on a hydraulic torque converter according to claim 1, characterized in that, The improved genetic algorithm is the second-generation NSGA algorithm.

9. A front-end speed-regulating wind turbine transmission chain, characterized in that, The transmission chain of the wind turbine generator set with speed regulation at the front end of the hydraulic torque converter was designed using the design method described in any one of claims 1-8.

10. The front-end speed-regulating wind turbine transmission chain according to claim 9, characterized in that, The drive shaft is made of 40CrMo4 alloy steel, and the gears are made of 18CrNiMo7-6 carburized steel. The planetary gear bearings are selected from single-row or double-row cylindrical roller bearings, including SKF NCF3080CV or Koyo NU3352; The planetary carrier shaft uses tapered roller bearings, including TIMKENEE277455-277565 or SKFEE655270 / 655345.

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