A method and system for measuring the shaft coupling of a hydroelectric generator set based on the transfer of a marker point

Abstract

This invention provides a method and system for measuring couplings in hydro-generator sets based on marker point transfer, relating to the field of hydro-generator set installation and measurement technology. The method involves: S1: Setting reference marker points: Installing at least three non-collinear reference marker points on the runner and turbine shaft to be coupled; S2: Performing independent shape measurements on the runner and turbine shaft to determine their respective measurement references and obtaining a spatial positional relationship model between them and their respective component measurement references; S3: Measuring the current spatial coordinates of the reference marker points already set on the runner and turbine shaft; S4: Based on the reference marker point coordinates and the spatial positional relationship model, calculating the actual spatial position and orientation of the currently obscured runner coupling surface and turbine shaft coupling surface. This method achieves digital control of coupling accuracy, improves coupling operation efficiency, enhances measurement accuracy and reliability, increases installation efficiency, and improves the applicability of the method.

Description

Technical Field

[0001] This invention relates to the field of hydro-generator installation measurement technology, and in particular to a method and system for measuring the coupling of hydro-generators based on marker point transfer. Background Technology

[0002] During the installation of hydro-generator units, the alignment of the turbine shaft and runner coupling is a core process that determines the quality of the unit's installation. Key precision indicators such as coaxiality and flange parallelism directly affect the unit's operational stability, vibration amplitude, and service life. The industry has stringent tolerance requirements for this process; typically, the coaxiality of the main shaft and runner must be controlled within 0.05mm, and the levelness within 0.035mm. These high precision requirements pose significant challenges to measurement methods.

[0003] Currently, traditional coupling measurement methods mostly rely on manual operation and conventional measuring tools. The basic process is as follows: first, the runner is adjusted to a horizontal state using equipment such as a frame level, then the turbine shaft is hoisted, the gap between the coupling surfaces is checked using a feeler gauge, and the horizontality of the end face is observed through the top surface of the turbine shaft. For coaxiality testing, four plumb lines are symmetrically suspended from the top of the shaft, and the distance from each position to the axis is measured using electrical measurement methods, thereby calculating the coaxiality.

[0004] The above methods have several inherent drawbacks: First, feeler gauge testing and plumb line observation are easily affected by manual estimation and environmental interference, resulting in significant cumulative errors and failing to meet micron-level accuracy requirements. Second, repeated adjustments, hoisting, and re-measurement are required, leading to high labor intensity and a lengthy installation cycle due to the numerous adjustments. Third, for large hydro-generator units, the large turbine shaft height makes the plumb line susceptible to airflow disturbances and suspension deviations, making actual measurement difficult and creating a technical bottleneck.

[0005] Furthermore, traditional methods cannot address the problem of key measurement reference surfaces being obscured during the coupling process. As the turbine shaft and runner gradually approach and mate, their coupling surfaces obscure each other, making direct observation and measurement impossible. Only indirect calculations can be relied upon, further amplifying measurement errors. With the increasing scale and precision of hydropower projects, the limitations of traditional measurement methods are becoming increasingly apparent, becoming a core obstacle restricting the efficient and high-quality installation of large-scale hydro-generator units. Summary of the Invention

[0006] The main objective of this invention is to provide a method for measuring the coupling of a hydro-generator set based on marker point transfer, which solves the problems of low measurement accuracy and reliability, low operating efficiency, limited applicability, and obstruction of key measurement reference surfaces.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for measuring the coupling of a hydro-generator unit based on marker point transfer, comprising the following steps: S1: Reference marker setting: Install at least three non-collinear reference markers on the runner and turbine shaft to be coupled, respectively. The reference markers are located in areas that are easy to observe during coupling operations. S2: Independent Measurement and Modeling of Components: Before the runner and turbine shaft are officially coupled, their shapes are measured independently to determine the rotation axis of the runner and its top coupling surface, and the rotation axis of the turbine shaft and its lower coupling surface as their respective measurement references; at the same time, the precise spatial positional relationship model between each reference marker point and its corresponding component measurement reference is measured and obtained. S3: Coupling indirect measurement: When the runner and turbine shaft are aligned by coupling and their coupling surfaces are mutually obscured, measure the current spatial coordinates of the reference markers set on the runner and turbine shaft; S4: Information Back-Calculation and Adjustment Guidance: Based on the coordinates of the reference marker points measured in step S3, and combined with the spatial position relationship model established in step S2, back-calculate the actual spatial position and attitude of the occluded runner coupling surface and turbine shaft coupling surface in the current state; compare this actual information with the design alignment requirements, and guide the adjustment of component positions and attitudes based on the comparison results until the coupling accuracy requirements are met.

[0008] In the preferred embodiment, step S2 specifically includes: The coupling plane and rotation axis of the runner and turbine shaft are obtained by least squares fitting. The orthogonal positional relationship between the fitted plane and the fitted rotation axis is checked. Then, a local coordinate system of the component is established. At the same time, the coordinates of each reference point in the local coordinate system are measured and obtained. Through coordinate transformation, the transformation relationship between the coordinate system composed of the reference points and the component measurement reference coordinate system is established, forming a precise spatial positional relationship model represented by translation vectors and rotation matrices. The spatial positional relationship model satisfies the rigid body transformation formula: ; in, Let these be the coordinates of a point on the component in the local coordinate system. These are the coordinates of the point in the global measurement coordinate system. Let be a rotation matrix. It is a translation vector.

[0009] In the preferred scheme, step S3 specifically includes: Based on the global coordinates of the reference markers measured in step S3, and combined with the spatial position relationship model established in step S2, the optimal rigid body transformation between the three-dimensional point sets is solved using the least squares method through absolute orientation and point set registration techniques, i.e., solving... By obtaining the rotation matrix R and the translation vector t, the actual spatial position and attitude of the occluded runner coupling surface and turbine shaft coupling surface under the current state can be calculated.

[0010] In the preferred embodiment, in step S1, the installation position of the reference marker point encloses the largest possible range of its component. The quantitative requirements are: the total length of the component enclosed by the marker point is ≥80%, the total perimeter is ≥90%, and under extreme working conditions, the total length is ≥75% and the total perimeter is ≥85%.

[0011] In the preferred embodiment, the number of reference markers set on the runner and turbine shaft in step S1 is redundant; The redundancy setting is as follows: 3 main marker points and 2 spare marker points are set on the turbine shaft, and 4 main marker points and 2 spare marker points are set on the runner; the spare marker points are arranged in the gaps between the main marker points and are distributed at a preset angle with the adjacent main marker points.

[0012] In the preferred embodiment, in step S1, the installation position of the reference marker is between the coupling surfaces at both ends of the turbine shaft and at the positions of the upper and lower leak-proof rings of the runner, and avoids functionally prohibited areas such as welds, stress concentration areas, sealing surfaces, mating surfaces, and flow channels of the components.

[0013] In the preferred embodiment, in step S2, the formula for fitting the plane of the rotor coupling using the least squares method is: ; in, It is a plane normal vector. It is a constant. The measurement point is located on the coupling plane. The rotation axis of the runner is the line connecting the centers of the fitted circles of its upper and lower leak-proof rings, and the rotation axis of the turbine shaft is the line connecting the centers of the fitted circles of its upper and lower ends. The center coordinates of both are determined by projecting the fitted circles.

[0014] In the preferred scheme, the specific process of solving for the optimal rigid body transformation using the least squares method in step S4 is as follows: S41: Calculate the point set of the reference marker in the local and global coordinate systems. and Solve for the local centroid of the wheel's marker point. and the global centroid of the rotating wheel marker point ; S42: Decentralize the two sets of points to obtain: , ; in, These are the local coordinates of the wheel marker point. The global coordinates of the wheel marker point; S43: Constructing the matrix SVD decomposition to obtain ; in, for The transpose of the matrix, It is a left singular matrix. This is the transpose of a right singular matrix. It is a singular value matrix; S44: Calculate the rotation matrix: ,like Then Recalculate after inverting the third column; S45: Calculate the translation vector: - ; Similarly, the transformation of the turbine shaft can be obtained.

[0015] Secondly, the present invention provides a hydro-generator coupling measurement system based on marker point transfer, characterized in that it is applicable to the aforementioned hydro-generator coupling measurement method based on marker point transfer, comprising: The measurement module is used to perform shape measurement on the runner and turbine shaft and spatial coordinate measurement on the benchmark point. It can also realize multi-station observation and coordinate stitching. The marker point group includes multiple sets of reference marker points that are fixedly installed on the runner and turbine shaft, respectively. The marker point group includes main marker points and spare marker points, and is fixed by a magnetic base combined with a threaded set screw locking method. The data processing and control module is used to receive measurement data from the measurement module, establish and store the spatial position relationship model through algorithms such as least squares method and SVD decomposition, perform pose inverse calculation of the occluded coupling surface, compare actual information with design requirements, and output adjustment guidance information for component pose. It can also complete real-time data updates and accuracy verification after adjustment.

[0016] In the preferred embodiment, the measurement module is a laser tracker, which is set up in a stable area 1.5-3m away from the component, and calibration is performed every 10 points during the measurement process; The data processing and control module is based on secondary development of the working software of the laser tracking measurement system. It can display the center deviation of the coupling surface, the included angle of the axis, the adjustment direction and the adjustment amount in real time, and supports both graphical and digital display.

[0017] This invention provides a method for measuring couplings of a hydro-generator set based on marker point transfer. The method comprises: S1: Setting reference marker points: Installing at least three non-collinear reference marker points on the runner and turbine shaft to be coupled; S2: Performing independent shape measurements on the runner and turbine shaft to determine their respective measurement references; simultaneously, measuring and obtaining a precise spatial positional relationship model between each reference marker point and its corresponding component measurement reference; S3: When aligning the coupling and the coupling surfaces are mutually obscured, measuring the current spatial coordinates of the reference marker points already set on the runner and turbine shaft; S4: Information back-calculation and adjustment guidance: Based on the reference marker point coordinates and the established spatial positional relationship model, back-calculating the actual spatial position and orientation of the obscured runner coupling surface and turbine shaft coupling surface in the current state; comparing this actual information with the design alignment requirements, and guiding the adjustment of component orientation based on the comparison results; achieving digital control of coupling accuracy, improving coupling operation efficiency, measurement accuracy and reliability, and increasing installation efficiency and applicability of the method. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a pre-assembly diagram of the runner coupling of the large hydro-generator unit of the present invention; Figure 2 This is a schematic diagram of the coupling detection points of the present invention; Figure 3 This is a schematic diagram of the wheel shape measurement and marker point layout of the present invention (upper crown side). Figure 4 This is a digital model of the rotary wheel of the present invention and a diagram showing the relationship between the reference surface and the position of the marker point; Figure 5 This is a schematic diagram of the turbine shaft shape measurement and marker point layout of the present invention (coupling end side). Figure 6 This invention relates to a digital model of the turbine shaft and a diagram showing the relationship between the reference surface and the marker points. Figure 7 This is a schematic diagram of the observation of the marker points during coupling docking according to the present invention; Figure 8 This is a schematic diagram of the envelope range of the marker points in this invention (rotating wheel); Figure 9 This is a schematic diagram of the envelope range of the marker points of the present invention (hydro turbine shaft). Detailed Implementation

[0019] Example 1 like Figure 1-9 As shown, a method for measuring the coupling of a hydro-generator unit based on marker point transfer includes the following steps: S1: Reference marker setting: Install at least three non-collinear reference markers on the runner and turbine shaft to be coupled, respectively. The reference markers are located in positions that are easy to observe during coupling operations.

[0020] S2: Independent Measurement and Modeling of Components: Before the formal coupling of the runner and turbine shaft, independent shape measurements are performed on both to determine the top coupling surface of the runner and the lower coupling surface of the turbine shaft as their respective measurement references. Simultaneously, a precise spatial positional relationship model between each reference marker point and its corresponding component measurement reference is measured and obtained. Specifically: The coupling plane and rotation axis of the runner and turbine shaft are obtained by least squares fitting. The orthogonal positional relationship between the fitted plane and the fitted rotation axis is checked. Then, a local coordinate system of the component is established. At the same time, the coordinates of each reference point in the local coordinate system are measured and obtained. Through coordinate transformation, the transformation relationship between the coordinate system composed of the reference points and the component measurement reference coordinate system is established, forming a precise spatial positional relationship model represented by translation vectors and rotation matrices. The spatial positional relationship model satisfies the rigid body transformation formula: ; in, Let these be the coordinates of a point on the component in the local coordinate system. These are the coordinates of the point in the global measurement coordinate system. Let be a rotation matrix. It is a translation vector.

[0021] S3: Coupling indirect measurement: When the runner and turbine shaft are aligned by coupling and their coupling surfaces are mutually obscured, measure the current spatial coordinates of the reference markers already set on the runner and turbine shaft.

[0022] S4: Information Back-Calculation and Adjustment Guidance: Based on the global coordinates of the reference marker points measured in step S3, and combined with the spatial position relationship model established in step S2, the optimal rigid body transformation between the three-dimensional point sets is solved using the least squares method through absolute orientation and point set registration techniques, i.e., solving... The rotation matrix R and translation vector t are obtained. The actual spatial position and attitude of the occluded runner coupling surface and turbine shaft coupling surface under the current state are calculated. This actual information is compared with the design alignment requirements, and the component attitude is adjusted according to the comparison results.

[0023] S5: Closed-loop verification: Every time the component position is adjusted, the coordinates of the reference marker point are immediately remeasured and the data is updated to guide the next operation in real time until the coupling accuracy meets the design requirements; after the component position adjustment is completed, the runner and turbine shaft are tightened. After tightening, the coordinates of the marker point are measured again and the coupling surface attitude is calculated in reverse to verify that the accuracy is not offset after tightening.

[0024] In this embodiment, by independently measuring the shape of the runner and turbine shaft of the coupling and installing reference markers on them, a spatial positional relationship model between each reference marker and its corresponding component measurement reference is obtained. Indirect coupling measurement is then performed to calculate the actual spatial position and orientation of the runner coupling surface and turbine shaft coupling surface that are currently obscured. This actual information is compared with the design alignment requirements, and the component orientation is adjusted based on the comparison results. This solves the technical problem of being unable to directly measure key reference surfaces when coupling is obscured, realizes digital control of coupling accuracy, improves coupling operation efficiency, measurement accuracy and reliability, installation efficiency, and the applicability of the method.

[0025] like Figure 1 The image shows the pre-assembly process of the runner coupling of a large hydro-generator unit. It illustrates the overall pre-assembly scenario before the runner and turbine shaft are coupled, marking the relative installation positions of the runner and turbine shaft and the boundaries of the work space. This visually demonstrates the problem of the reference plane being easily obscured in traditional pre-assembly. Figure 2 The diagram shows the coupling inspection points. Key inspection points are marked on the coupling surface at the top of the runner and the coupling surface at the bottom of the turbine shaft. These points correspond to the coaxiality and levelness inspection locations in Table 1, clearly demonstrating the core control points for coupling accuracy and clarifying the common inspection targets of traditional measurement and the method of this invention. Relevant tolerances are shown in Table 1.

[0026] Table 1 Tolerances for Runner Couplings

[0027] Traditional coupling measurement methods first use equipment such as a frame level to adjust the runner to be level, then install the turbine shaft, use a feeler gauge to check the gap between the coupling surfaces, and check the levelness of the turbine shaft end face at the top. For coaxiality testing, four plumb lines are symmetrically suspended from the top of the turbine shaft, and the distance from each position to the axis is measured using an electrical measuring method, and then the coaxiality is calculated based on these measurements.

[0028] The core mathematical principle of this embodiment is rigid body kinematics and coordinate system transformation. By using marker points as spatial reference points, the pose of the occluded coupling surface is indirectly solved. The entire process involves absolute orientation and point set registration techniques, essentially using the least squares method to solve for the optimal rigid body transformation between two 3D point sets, including: (1) Rigid body transformation: The movement (translation and rotation) of a component in space can be described by a rigid body transformation: ; in Let these be the coordinates of a point on the component in the local coordinate system. These are the coordinates of the point in the global measurement coordinate system. For rotation matrix (orthogonal matrix, ), It is a translation vector.

[0029] (2) Absolute orientation: Given two sets of three-dimensional points and Find the optimal one and Make: .

[0030] The main calculation process is as follows: (1) Determination of the geometric datum of the runner 1. Reference plane fitting: Measuring the upper coupling plane of the rotating wheel Points The least squares method is used to fit the plane: .

[0031] Where d is the plane constant, Here, m represents the reference plane measurement points, and m represents the number of reference plane measurement points. It is the plane normal vector.

[0032] Solving for the plane normal vector and constant The plane equation is: .

[0033] Take the center of mass ,have .

[0034] in, The reference plane for the wheel, The unit normal vector of the reference plane, Let be the coordinates of any point on the plane. is the reference plane constant.

[0035] 2. Calculation of average elevation of the leak-stopping ring: Measurement of the circumferential point set of the leak-stopping ring Lower leak-stopping ring circumferential point set .

[0036] Calculate the average elevation (along the normal direction) (directed distance) , ; in, , This represents the number of measured points on the upper and lower leak-stopping rings.

[0037] 3. Construct parallel planes: Draw parallel planes to the reference plane through the average elevations of the upper and lower leak-stopping rings respectively. , ; 4. Projection and Circular Fitting: Project the circumferential detection points of the upper leak-stopping ring onto... : ; in, This represents the projection deviation.

[0038] exist The center of the circle is obtained by performing least-squares circle fitting. and radius .

[0039] Project the circumferential detection points of the lower sealing ring onto... :

[0040] Fitting the center of the circle and radius .

[0041] 5. Determining the axis of rotation The axis of rotation of the wheel is and The connection: ; in, Let the axis of rotation be the unit vector. The fitting center of the upper and lower stop-leak rings is used. The vector is the center vector.

[0042] 6. Establishment of Local Coordinate System Origin of coordinate system For the axis of rotation and Intersection point:

[0043] Establish a right-handed coordinate system: Z-axis: (The direction is agreed upon).

[0044] X-axis: Select reference direction (e.g., pointing to a certain landmark):

[0045] Y-axis: .

[0046] Obtain the local coordinate system .

[0047] (2) Determination of the geometric datum of the turbine shaft 1. Fitting the upper and lower end planes Measurement of the upper end face point set of the turbine shaft Fitting plane ; Measurement of lower end face point set Fitting plane .

[0048] 2. Top and bottom circular projections and fitting Measurement of the upper circumferential point set Projected onto : .

[0049] exist By fitting a circle to the top, the center of the circle can be obtained. and radius .

[0050] Measurement of the lower circumferential point set Projected onto : .

[0051] exist By fitting a circle to the top, the center of the circle can be obtained. and radius .

[0052] 3. Determining the axis of rotation: The axis of rotation of the turbine shaft is the line connecting the centers of the upper and lower circles: .

[0053] 4. Establishment of local coordinate system Origin of coordinate system The axis of rotation and the lower end plane Intersection point: ; Similar to establishing a right-handed coordinate system .

[0054] (3) Marker point calibration Measure the coordinates of the marker point in the local coordinate system: The first wheel One marker point: .

[0055] The first on the turbine shaft One marker point: .

[0056] (4) Coupling measurement and pose inverse calculation 1. Global coordinate measurement: In the global coordinate system Measurement markers: Rotary wheel marker: .

[0057] Turbine shaft marking points: .

[0058] 2. Solving by rigid body transformation In the preferred scheme, the specific process of solving for the optimal rigid body transformation using the least squares method in step S4 is as follows: S41: Calculate the point set of the reference marker in the local and global coordinate systems. and Solve for the local centroid of the wheel's marker point. and the global centroid of the rotating wheel marker point .

[0059] S42: Decentralize the two sets of points to obtain: ,

[0060] in, These are the local coordinates of the wheel marker point. These are the global coordinates of the wheel marker point.

[0061] S43: Constructing the matrix SVD decomposition to obtain ; in, for The transpose of the matrix, It is a left singular matrix. This is the transpose of a right singular matrix. It is a singular value matrix.

[0062] S44: Calculate the rotation matrix: ,like Then The third column is inverted and then recalculated.

[0063] S45: Calculate the translation vector: - .

[0064] Similarly, the transformation of the turbine shaft can be obtained. .

[0065] 3. Coupling pose inverse calculation In the local coordinate system, the wheel coupling surface is the reference plane. (correspond (plane), with the origin at its center. The normal vector is In the global coordinate system: center: ,(in, ).

[0066] Normal vector: .

[0067] The lower end of the turbine shaft is a plane in the local coordinate system. (correspond (plane), with the origin at its center. The normal vector is In the global coordinate system: center: ,(in, ).

[0068] Normal vector: .

[0069] The technical solution in this example is described clearly and completely, step by step.

[0070] I. Preliminary Preparations Equipment and tool preparation: A laser tracker with an accuracy of ±0.001mm is selected as the core equipment of the measurement module, along with a magnetic base (with threaded set screw), reference markers (target ball seat), a special runner support bracket, an adjustable support for the turbine shaft, jacks, wedges, and a data processing terminal (an industrial computer pre-installed with secondary development software, forming a data processing and control module).

[0071] Site environment assessment: Clear the coupling operation area to ensure that the potential installation area of ​​the laser tracker (within 1.5-3m of the component) is free of vibration sources and obstructions; investigate the structural form of the runner and turbine shaft and the coupling operation space, identify prohibited areas such as component welds, stress concentration areas, and leak-proof ring sealing surfaces, and mark permanent and temporary exposed areas to lay the foundation for the placement of marker points.

[0072] Drawing and model preparation: retrieve the design drawings of the runner and turbine shaft, establish a simplified geometric model of the components in the measurement software, clarify the spatial position of the top coupling surface of the runner and the lower coupling surface of the turbine shaft, and mark the geometric center, maximum outline dimension and center of gravity section of the components as the basis for the layout of the marker points.

[0073] like Figure 3 As shown, the diagram illustrates the state of the independent shape of the rotor, marks the location of the laser tracker, and clearly shows the layout of the main / backup markers on the crown plane of the rotor and above the leak-proof ring, reflecting the layered and directional layout and redundant layout characteristics.

[0074] like Figure 5As shown, this diagram illustrates the state of the turbine shaft during independent shape measurement, marking the locations of the main / standby markers in the upper and middle sections of the shaft and the flange transition section, and clarifying the measurement angle of the laser tracker.

[0075] Before coupling, the runner and turbine shaft are hoisted to convenient measurement positions. The runner is fixed with a special bracket, and the turbine shaft is positioned with an adjustable support. They are then hoisted to convenient measurement positions, and the support structure is adjusted to ensure that the vibration amplitude of the components is ≤0.005mm when stationary, with no obvious shaking.

[0076] II. Setting up reference marker points: Reference marker points are set up between the coupling surfaces at both ends of the turbine shaft and at the positions of the upper and lower leak-proof rings of the runner. The marker points are divided into main marker points and spare marker points, and are fixed by magnetic bases combined with threaded set screws. The total length of the marker point envelope component is ≥80% and the total circumference is ≥90%. Under extreme operating conditions, the total length of the envelope is ≥75% and the total circumference is ≥85%, as shown in Table 2.

[0077] Table 2

[0078] In this embodiment, using marker points to solve for the 6-DOF pose of the component (3 translations + 3 rotations) is essentially solving a geometrically constrained optimization problem. The spatial distribution of the marker points directly affects the observability and estimation accuracy of the pose parameters. Specific requirements are as follows: 1. Minimum number: at least 3 non-collinear points (to determine the plane orientation); Recommended number: 4-6 points (to provide redundancy and improve robustness); Non-coplanarity: if possible, the 4 points should be non-coplanar (fully constraining 6 degrees of freedom).

[0079] 2. Spatial distribution requirements (1) Three-dimensional envelope criterion Let the set of marker points be ,definition: Center of mass: .

[0080] Scatter matrix: .

[0081] Effective volume: (approximate).

[0082] Requirement: Maximize This ensures that the volume of the convex hull formed by the marker points is maximized.

[0083] (2) Directional uniformity Calculate the eigenvalues ​​of the covariance matrix of the marker coordinates. : Ideal distribution: (Isotropic).

[0084] Avoid degradation: (Avoid being too flat in one direction), and avoid axes of symmetry, irregular layouts, and functional areas.

[0085] (3) Use the precision factor (DOP) index to evaluate layout quality. Define the precision factor matrix: , where A is the design matrix.

[0086] minimize or .

[0087] In this embodiment, all marker points are located away from areas where the component functions are prohibited and are situated in positions that are easy to observe throughout the coupling operation (appropriate angle: the angle between the line connecting the marker point and the measuring instrument and the surface normal should be greater than 30°). Spare marker points are used for supplementary measurements when the main marker point is slightly obstructed or damaged, ensuring measurement continuity and improving the operability and standardization of the method.

[0088] In this embodiment, the specific location is suggested as follows: I. Rotating Wheel: Upper crown: close to the coupling surface but in an asymmetrical position (2-3 points); Lower ring: close to the lower leak-proof ring position (2 points); Blade root: select 1-2 blades and arrange them alternately on the pressure surface and suction surface; Envelope range: make full use of the entire height of the impeller, from the coupling surface to the lower ring.

[0089] II. Turbine Shaft: Upper flange: asymmetrical position (2 points); middle of shaft: if space permits (1-2 points); lower flange: near the coupling surface but avoiding the mating area (2 points); envelope: covers the entire length of the shaft, especially both ends.

[0090] In this embodiment, the marker device should use a target ball holder with strong magnetic force and be firmly attached to the component using hot melt adhesive. The precision parameters for adjusting each component are shown in Table 3.

[0091] Table 3 Measurement Accuracy Control Parameters

[0092] like Figure 8 As shown, the smallest circumscribed geometry composed of the rotating wheel markers is outlined with dashed lines, and the key areas covered by the envelope, such as the upper crown plane and the area above the leak-stopping ring, are marked, which improves the rationality of the envelope layout.

[0093] In the preferred embodiment, in step S2, the formula for fitting the plane of the rotor coupling using the least squares method is: ; in, It is a plane normal vector. It is a constant. These are the measurement points on the coupling plane.

[0094] The rotation axis of the runner is the line connecting the centers of the fitted circles of its upper and lower leak-proof rings, and the rotation axis of the turbine shaft is the line connecting the centers of the fitted circles of its upper and lower ends. The center coordinates of both are determined by projecting the fitted circles.

[0095] This embodiment maximizes the envelope of the key area of ​​the component by using marker points, ensuring that the spatial positional relationship model between the marker points and the measurement reference covers the core positioning area of ​​the component, thereby improving the model fitting accuracy.

[0096] like Figure 4 As shown, the digital model of the wheel, built based on the shape measurement data, marks the spatial position of the top coupling surface (measurement reference) and each marker point, intuitively presenting the coordinate relationship between the two.

[0097] like Figure 9 As shown, the smallest circumscribed cylinder formed by the turbine shaft markers is outlined with dashed lines, and the envelope areas such as the middle section of the shaft and the flange transition section are marked. The edge layout of the spare markers is also indicated, reflecting the redundancy layout supplementary feature and improving the envelope reliability under extreme working conditions.

[0098] This embodiment, through redundant layout, ensures the integrity of the measurement group even under extreme working conditions (obstruction / damage of the main marker point), improves the method's anti-interference capability and operational continuity, enhances system operational stability, and avoids operational interruptions due to single-point failures.

[0099] III. Independent Measurement and Modeling of Components Step S3: Independent measurement and modeling of components.

[0100] like Figure 5 As shown, a digital model of the turbine shaft is displayed, with the spatial correspondence between the lower coupling surface (measurement reference) and each marker point marked, demonstrating the model mapping logic of translation vectors and rotation matrices.

[0101] 1. Shape Measurement: The runner is securely fixed with a dedicated bracket, and the turbine shaft is positioned using an adjustable support (ensuring it remains stationary without shaking). The laser tracker is activated and set up in a preset stable area, with calibration performed every 10 measurement points. Independent shape measurements are taken of the runner and turbine shaft separately to obtain the runner's external dimensions, top coupling surface flatness, and center hole data, as well as the turbine shaft's external dimensions and lower coupling surface flatness data. These data are simultaneously transmitted to the data processing terminal to clarify the respective measurement benchmarks for both.

[0102] In the preferred embodiment, the spatial position relationship model established in step S2 is a transformation relationship between a coordinate system composed of reference marker points established through coordinate transformation and a component measurement reference coordinate system; In steps S2 and S3, a laser tracker is used to measure the shape and coordinates of the reference marker points.

[0103] This embodiment achieves a precise mathematical mapping between benchmark points and measurement benchmarks. Compared with traditional indirect calculations, it eliminates estimation and systematic errors and improves the model fitting accuracy.

[0104] In the preferred embodiment, the marker point is installed between the coupling surfaces at both ends of the turbine shaft, at the location of the upper and lower leak-proof rings of the runner. The installation position of the marker point avoids the functional areas of the component (welds, sealing surfaces), thus ensuring the exposure of the marker point throughout the coupling, reducing external interference with the component assembly accuracy, and adapting to the structural characteristics of the component, further improving the stability of the marker point fixation.

[0105] 2. Establishment of Spatial Position Relationship Model: During shape measurement, a laser tracker is used to accurately acquire the three-dimensional coordinates of all reference marker points. Combined with the component measurement reference, a transformation relationship is established between the coordinate system composed of reference marker points and the component measurement reference coordinate system. The spatial position relationship model is obtained by fitting using the least squares method, represented in the form of translation vectors and rotation matrices. The model fitting accuracy is controlled within 0.002mm, and the model is stored by the data processing and control module for later use.

[0106] IV. Indirect measurement via coupling, including: Preliminary component docking: Securely position the turbine runner in the work area (precise leveling is not required; ensuring static stability is sufficient). Use hoisting equipment to lift the turbine shaft above the runner and adjust it to the preliminary docking position. At this point, the coupling surfaces of the two components are close to each other and completely obscure each other, making direct measurement impossible. Figure 7 As shown, this diagram illustrates the scene after the runner and turbine shaft are initially connected and the coupling surface is completely obscured. The observation positions of the laser tracker at multiple stations and the observation range of the exposed marker points are marked.

[0107] Marker point coordinate measurement: The laser tracker is adjusted to a position that can simultaneously observe all main marker points of the runner and turbine shaft. The current spatial coordinates of exposed marker points are collected using a multi-station observation method. After each station observation is completed, the coordinates are stitched together (stitching accuracy ≤ 0.003mm). If some main marker points are slightly obscured, backup marker points are used to supplement the measurement. The measurement data is transmitted to the data processing and control module in real time.

[0108] V. Information Reverse Calculation and Pose Adjustment Guidance After receiving the global coordinate data of the marker points, the data processing and control module performs the following operations and guides the on-site pose adjustment: Inverse pose calculation: A pre-stored spatial relationship model is invoked, combined with the measured global coordinates of the marker points, and using absolute orientation and point set registration techniques, the least squares method is employed to solve for the optimal rigid body transformation between 3D point sets (solving ∑...). qi (Rpi+t) (2→min) to calculate the actual spatial position and attitude of the occluded runner coupling surface and turbine shaft coupling surface under the current state, including key parameters such as the center coordinates of the coupling surface, the direction of the normal vector, and the included angle of the axis.

[0109] Deviation comparison: The actual position and pose information obtained by back calculation is compared with the design alignment requirements in real time to calculate the deviation data such as the center deviation of the coupling surface and the included angle of the axis. The design alignment requirements are that the coaxiality of the main spindle and the wheel is ≤0.05mm and the levelness is ≤0.035mm.

[0110] Real-time adjustment guidance: The data processing and control module displays deviation data, adjustment direction, and adjustment amount (movement distance, vertical adjustment angle) on the terminal in graphical (coupling surface pose simulation, deviation annotation) and digital (specific values) form, guiding operators to fine-tune the position of the runner or turbine shaft using tools such as jacks and wedges.

[0111] Dynamic updates: Every time the component pose is adjusted, the laser tracker immediately re-acquires the global coordinates of the marker point, the measurement system synchronously updates the data and completes a new round of pose inversion and deviation comparison, providing real-time guidance for the next adjustment operation until the coupling accuracy meets the design alignment requirements.

[0112] The data processing and control module, implemented through secondary software development, can calculate and display the center deviation and the included angle of the axes of the two obscured coupling surfaces in real time. The module calls a pre-stored spatial relationship model and, combined with the measured current coordinates of the marker points, calculates the actual spatial position and attitude of the obscured coupling surface at the top of the runner and the coupling surface at the bottom of the turbine shaft.

[0113] VI. Tightening Operation and Closed-Loop Verification Operators fine-tune the position and posture of the impeller or turbine shaft using tools such as jacks and wedges, based on the adjustment guidance information output by the terminal (movement direction, distance, verticality adjustment angle). After each adjustment, the laser tracker immediately re-acquires the coordinates of the marker point, and the measurement system updates the data synchronously, providing real-time guidance for the next operation until the coupling accuracy meets the requirements (coaxiality ≤ 0.05mm, horizontality ≤ 0.035mm).

[0114] After confirming that the accuracy meets the standard, the runner and turbine shaft are tightened. After tightening, the coordinates of the marker point are measured again, the coupling surface attitude is calculated, and the accuracy is verified to be without deviation after tightening. Finally, the coupling closed-loop operation is completed.

[0115] This embodiment visualizes deviation information, reduces the workload and skill threshold for operators, avoids human error, and improves measurement accuracy.

[0116] This embodiment solves the technical bottleneck of coupling in large hydro-generator units through the synergistic effect of the above steps, and realizes the comprehensive technical advantages of high precision, high efficiency, high reliability and strong versatility. It improves measurement accuracy (micrometer level), shortens the installation cycle, significantly reduces labor intensity, and provides a brand-new technical path for the precision assembly of large hydropower equipment.

[0117] Example 2 Further illustrating with reference to Embodiment 1, a hydro-generator coupling measurement system based on marker point transfer, applicable to the hydro-generator coupling measurement method based on marker point transfer in Embodiment 1, includes: The measurement module is used to perform shape measurement on the runner and turbine shaft and spatial coordinate measurement on the benchmark point. It can also realize multi-station observation and coordinate stitching. The marker point group includes multiple sets of reference marker points that are fixedly installed on the runner and turbine shaft, respectively. The marker point group includes main marker points and spare marker points, and is fixed by a magnetic base combined with a threaded set screw locking method. The data processing and control module is used to receive measurement data from the measurement module, establish and store the spatial position relationship model through algorithms such as least squares method and SVD decomposition, perform pose inverse calculation of the occluded coupling surface, compare actual information with design requirements, and output adjustment guidance information for component pose. It can also complete real-time data updates and accuracy verification after adjustment.

[0118] In the preferred embodiment, the measurement module is a laser tracker, which is set up in a stable area 1.5-3m away from the component, and calibration is performed every 10 points during the measurement process.

[0119] The data processing and control module is based on the secondary development of the working software of the laser tracking measurement system. It can display the center deviation of the coupling surface, the included angle of the axis, the adjustment direction and the adjustment amount in real time, and supports both graphical and digital display.

[0120] This embodiment provides a method for measuring the coupling of a hydro-generator set based on marker point transfer, including its working process, details, and technical effects. Please refer to Embodiment 1 for further details.

[0121] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for measuring the shaft coupling of a hydroelectric generating unit based on the transfer of a marker point, characterized in that, Includes the following steps: S1: Reference marker setting: Install at least three non-collinear reference markers on the runner and turbine shaft to be coupled, respectively. The reference markers are located in areas that are easy to observe during coupling operations. S2: Independent Measurement and Modeling of Components: Before the runner and turbine shaft are officially coupled, their shapes are measured independently to determine the rotation axis of the runner and its top coupling surface, and the rotation axis of the turbine shaft and its lower coupling surface as their respective measurement references; at the same time, the precise spatial positional relationship model between each reference marker point and its corresponding component measurement reference is measured and obtained. S3: Coupling indirect measurement: When the runner and turbine shaft are aligned by coupling and their coupling surfaces are mutually obscured, measure the current spatial coordinates of the reference markers set on the runner and turbine shaft; S4: Information back calculation and adjustment guidance: Based on the coordinates of the reference marker points measured in step S3, and combined with the spatial position relationship model established in step S2, the actual spatial position and attitude of the occluded runner coupling surface and turbine shaft coupling surface under the current state are back calculated. The actual information is compared with the design alignment requirements, and the component position is adjusted according to the comparison results until the coupling accuracy requirements are met.

2. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 1, characterized in that, Step S2 is as follows: The coupling plane and rotation axis of the runner and turbine shaft are obtained by least squares fitting. The orthogonal positional relationship between the fitted plane and the fitted rotation axis is checked. Then, a local coordinate system of the component is established. At the same time, the coordinates of each reference point in the local coordinate system are measured and obtained. Through coordinate transformation, the transformation relationship between the coordinate system composed of the reference points and the component measurement reference coordinate system is established, forming a precise spatial positional relationship model represented by translation vectors and rotation matrices. The spatial positional relationship model satisfies the rigid body transformation formula: ； in, Let these be the coordinates of a point on the component in the local coordinate system. These are the coordinates of the point in the global measurement coordinate system. For rotation matrix, It is a translation vector.

3. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 1, characterized in that, In step S4, specifically: Based on the global coordinates of the reference markers measured in step S3, and combined with the spatial position relationship model established in step S2, the optimal rigid body transformation between the three-dimensional point sets is solved using the least squares method through absolute orientation and point set registration techniques, i.e., solving... By obtaining the rotation matrix R and the translation vector t, the actual spatial position and attitude of the occluded runner coupling surface and turbine shaft coupling surface under the current state can be calculated.

4. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 1, characterized in that, In step S1, the installation position of the reference marker point encloses the largest possible range of its component. The quantitative requirements are: the total length of the component enclosed by the marker point is ≥80%, the total perimeter is ≥90%, and under extreme working conditions, the total length is ≥75% and the total perimeter is ≥85%.

5. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 3, characterized in that, In step S1, the number of reference markers set on the runner and turbine shaft is redundant; The redundancy setting is as follows: 3 main marker points and 2 spare marker points are set on the turbine shaft, and 4 main marker points and 2 spare marker points are set on the runner; the spare marker points are arranged in the gaps between the main marker points and are distributed at a preset angle with the adjacent main marker points.

6. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 1, characterized in that, In step S1, the installation position of the reference marker is between the coupling surfaces at both ends of the turbine shaft and at the positions of the upper and lower leak-proof rings of the runner, and avoids functionally prohibited areas such as welds, stress concentration areas, sealing surfaces, mating surfaces, and flow channels of the components.

7. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 1, characterized in that, In step S2, the formula for fitting the plane of the rotating shaft coupling using the least squares method is as follows: ； in, It is a plane normal vector. It is a constant. The measurement point is located on the coupling plane. The rotation axis of the runner is the line connecting the centers of the fitted circles of its upper and lower leak-proof rings, and the rotation axis of the turbine shaft is the line connecting the centers of the fitted circles of its upper and lower ends. The center coordinates of both are determined by projecting the fitted circles.

8. The method for measuring the coupling of a hydro-generator unit based on marker point transfer according to claim 1, characterized in that, In step S4, the specific process of solving for the optimal rigid body transformation using the least squares method is as follows: S41: Calculate the point set of the reference marker in the local and global coordinate systems. and Solve for the local centroid of the wheel's marker point. and the global centroid of the rotating wheel marker point ; S42: Decentralize the two sets of points to obtain: ， in, These are the local coordinates of the wheel marker point. The global coordinates of the wheel marker point; S43: Constructing the matrix SVD decomposition to obtain ; in, for The transpose of the matrix, It is a left singular matrix. This is the transpose of a right singular matrix. It is a singular value matrix; S44: Calculate the rotation matrix: ,like Then Recalculate after inverting the third column; S45: Calculate the translation vector: - ; Similarly, the transformation of the turbine shaft can be obtained.

9. A hydro-generator coupling measurement system based on marker point transfer, characterized in that, The method for measuring the coupling of a hydro-generator unit based on marker point transfer, applicable to any one of claims 1 to 8, includes: The measurement module is used to perform shape measurement on the runner and turbine shaft and spatial coordinate measurement on the benchmark point. It can also realize multi-station observation and coordinate stitching. The marker point group includes multiple sets of reference marker points that are fixedly installed on the runner and turbine shaft, respectively. The marker point group includes main marker points and spare marker points, and is fixed by a magnetic base combined with a threaded set screw locking method. The data processing and control module is used to receive measurement data from the measurement module, establish and store the spatial position relationship model through algorithms such as least squares method and SVD decomposition, perform pose inverse calculation of the occluded coupling surface, compare actual information with design requirements, and output adjustment guidance information for component pose. It can also complete real-time data updates and accuracy verification after adjustment.

10. The hydro-generator coupling measurement system based on marker point transfer according to claim 9, characterized in that, The measurement module is a laser tracker, which is set up in a stable area 1.5-3m away from the component. During the measurement process, calibration is performed every 10 points. The data processing and control module is based on secondary development of the working software of the laser tracking measurement system. It can display the center deviation of the coupling surface, the included angle of the axis, the adjustment direction and the adjustment amount in real time, and supports both graphical and digital display.

Images