A method for measuring the center of a hydropower station unit and its adjustment calculation

Abstract

The present invention discloses a method for measuring the center of a hydropower station unit, which includes the following steps: Step 1: set eight measuring points on a circular base and make the angle between two adjacent measuring points and the line connecting the center of the circle be 45°; Step 2: pass the vertical center line composed of a centroid, a piano wire and a weight through the center of the circular base; Step 3: scan the piano wire through a laser displacement sensor in a measuring component. The laser displacement sensor can read data, and the measuring component measures corresponding data at each measuring point in turn; Step 4: analyze the data measured by the measuring component using abnormal data. The present invention uses a laser displacement sensor measurement method to replace the traditional piano wire headphone method, which not only improves the measurement accuracy, but also makes the measurement operation relatively simple and more suitable for on-site operations. At the same time, the roundness calculated based on the least squares method is more accurate than the traditional direct calculation, and also overcomes the problem of poor consistency of multiple measurement results of traditional data.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy and hydropower, and in particular to a method for measuring the center of a hydropower station unit and adjusting and calculating the same. Background Art

[0002] The center measurement of a hydroelectric generator set is a key process in the installation and maintenance of a hydroelectric generator set. The conventional method mainly uses the piano wire and earphone method, which uses a piano wire, a measuring rod, and an earphone wire to form a loop. When the micrometer installed on the measuring rod touches the piano wire, the earphone wire is connected, and the earphone emits a sideways sound. At this time, the micrometer reading is the relative distance of the measuring point. Therefore, there are the following problems in the traditional measurement method:

[0003] (1) Since the measuring rod is long and heavy, the operator needs to adjust the micrometer at the end of the measuring rod, which makes it difficult to ensure the horizontal state of the measuring rod at all times, which often causes tilt deviation;

[0004] (2) The micrometer contact area is large, which often causes the piano wire to shake when it contacts the piano wire, affecting the measurement accuracy and often causing the measurement data to be too large;

[0005] (3) Each set of measured data varies greatly, making it difficult to evaluate its measurement accuracy.

[0006] (4) Traditional calculation methods often only use the maximum and minimum deviations among the eight measuring points to make center adjustments. There is no way to accurately measure the center offset, which often leads to multiple reworks.

[0007] (5) There are many parts of the hydropower station units that require central measurement. The previous method often made different measuring rods at different parts, resulting in a narrow range of application of the equipment and causing great waste.

[0008] Due to the above problems, not only the center measurement data is inaccurate, but also the adjustment method is inaccurate, which often causes operational accuracy and frequent rework, greatly wasting manpower and material resources, and delaying the installation and maintenance time of the unit. Summary of the invention

[0009] The object of the present invention is to provide a method for measuring the center of a hydropower station unit and adjusting the same to solve the problems in the background technology.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A method for measuring the center of a hydropower station unit and adjusting and calculating the same comprises the following steps: step 1: setting eight measuring points on a circular base and making the angle between two adjacent measuring points and the line connecting the center of the circle be 45 degrees; step 2: passing a vertical center line composed of a centroid, a piano wire and a weight through the center of the circular base; step 3: scanning the piano wire with a laser displacement sensor in a measuring component, the laser displacement sensor can read data, and the measuring component measures corresponding data at each measuring point in turn; step 4: analyzing the data measured by the measuring component using abnormal data;

[0012] The specific method of abnormal data analysis is: when the laser displacement sensor does not sweep the piano wire, the laser displacement sensor reading is the relative distance between the laser displacement sensor and the light shield, which is a certain value. When the laser displacement sensor sweeps the piano wire, the laser displacement sensor reading will change suddenly, and this sudden change is the relative distance between the laser displacement sensor and the piano wire. The data to be measured at the measuring point can be determined by using data abnormality analysis. In actual operation, using the principle that the straight line between two points is the shortest, at the same measuring point, the laser displacement sensor repeatedly sweeps over the piano wire, and takes its minimum value as the final measured data of the point.

[0013] On the basis of the above technical solution, the present invention also provides the following optional technical solution:

[0014] In an optional solution: eight measurement data measured by the measuring component at eight measurement points form a group of data, and at least three groups are measured.

[0015] In an optional solution: the diameter of the piano wire is 0.3 mm, and the spot area of ​​the laser displacement sensor should be less than 0.2 mm^2.

[0016] In an optional scheme: the measuring component includes a measuring rod, an extension rod, a light baffle and a laser displacement sensor; the extension rod is inserted into the measuring rod at one end and fixed by a positioning screw; the laser displacement sensor is installed at the end of the extension rod away from the measuring rod, and the end of the extension rod is also fixed to the light baffle by a connecting rod; the laser displacement sensor and the light baffle constitute a measuring unit, and the distance between the two should be within the measuring range of the laser displacement sensor; the measuring method of the measuring component is: the length of the extension rod is determined by adjusting the positioning screw to ensure that when the measuring rod and the laser displacement sensor sweep over the piano wire, the laser displacement sensor can read data.

[0017] A method for adjusting and calculating the center measurement of a hydropower station unit, wherein the data for adjustment and calculation is the measurement data obtained according to the above-mentioned method for measuring the center of a hydropower station unit, specifically comprising the following steps:

[0018] Assume that D groups of data are measured for the circular base, each group has N=8 data, corresponding to 8 evenly distributed points on the circular base.

[0019] First, the 95% confidence level is used to analyze the data in group D. ij (i∈[1N],j∈[1D]) should meet the following requirements:

[0020]

[0021] Then the B ij The measured mean value of the circular base at the i-th point is obtained by using the average calculation method based on the reliable data. If it does not meet the above formula, the data measurement is considered to be wrong and should be re-measured. At the same time, this method can also indicate in real time which measurement points have unreasonable data, providing reference opinions for the next data measurement.

[0022] Secondly, if the center of the circular base to be measured does not coincide with the piano wire, there will be an obvious accumulation effect in the measured data of the 8 test points, that is, the data of at least 3 points are smaller, while the data of the other points are larger.

[0023] Set Mean If the difference between the maximum and minimum values ​​is less than or equal to 0.02 mm, the center of the circular base is considered to coincide with the piano wire.

[0024] The mean value of each measurement point If it meets the following formula, the measured data is considered to be in a classified state and the next step of adjustment and calculation can be carried out.

[0025]

[0026] In the above formula, B′ represents the smallest 3 The mean of Represents 8 The mean of .

[0027] If the above conditions are not met, it is considered that the distribution of the data to be measured is unreasonable, there are obvious measurement error data, and it is necessary to re-measure and confirm.

[0028] After the above two conditions are met, each measured value can be Decompose it and calculate its components in the plane coordinate system:

[0029]

[0030] Each measuring point on the circular base is on the same circumference, and the measured The reason for the difference is that the center of the circular base does not coincide with the piano wire. Therefore, taking the projection of the piano wire on the plane of the circular base as the origin, each measuring point should conform to the following formula:

[0031] (xi -E) 2 +(y i -F) 2 =R 2

[0032] The above formula represents a typical circle formula, (E, F) for which the projection of the piano wire on the plane of the circle base is the center of the circle base as the origin. According to the least squares principle, the distance between each measuring point and the center of the fitting circle should satisfy the following formula.

[0033]

[0034] When all δ i When the derivatives of α, β, and γ are zero, the error is the smallest. For the convenience of calculation, δ i 2 Construct a new function and then find the derivatives of α, β, and γ according to the following formula.

[0035]

[0036] Then the eccentricity (E1, F1) can be calculated according to the following formula.

[0037]

[0038]

[0039]

[0040]

[0041]

[0042] Then the offset coordinates between the center of the circular base and the projection point of the piano line are (E2, F2), and the circular base to be measured is adjusted according to the offset coordinates.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention utilizes a laser displacement sensor measurement method to replace the traditional piano wire earphone method, which not only improves the measurement accuracy, but also makes the measurement operation relatively simple and more suitable for on-site operations. The combination of a measuring rod, an extension rod, a positioning screw, a connecting rod and its measurement range mark, and a light shield can ensure that the laser displacement sensor always has specific data. At the same time, it is convenient to adjust the length of the extension rod according to the position of the piano wire, thereby greatly improving the scope of application of the device. At the same time, the roundness calculated based on the least squares method is more accurate than the traditional direct calculation, and it also overcomes the problem of poor consistency of multiple measurement results of traditional data. Carrying out center measurement at different parts of the unit, using this device and method not only improves the calculation accuracy, but also expands the scope of measurement application, facilitates the measurement operation, and greatly saves manpower and material resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the center measurement of the hydropower station unit.

[0046] Figure 2 Schematic diagram of the measurement point distribution of the circular base.

[0047] Figure 3 This is a schematic diagram of the circular base projection coordinates.

[0048] Notes on the figure numbers: 1-centering device; 2-piano wire; 3-weight; 4-light baffle; 5-measuring rod; 6-positioning screw; 7-extension rod; 8-connecting rod; 9-laser displacement sensor; 10-circular base to be measured. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments; in the drawings or descriptions, similar or identical parts use the same reference numerals, and in practical applications, the shape, thickness or height of each component can be enlarged or reduced. The various embodiments listed in the present invention are only used to illustrate the present invention and are not used to limit the scope of the present invention. Any obvious modifications or changes made to the present invention do not depart from the spirit and scope of the present invention.

[0050] The center measurement of a hydroelectric generator set is a key process in the installation and maintenance of a hydroelectric generator set. The conventional method mainly adopts the piano wire earphone method, that is, a piano wire, a measuring rod and an earphone wire are used to form a loop. When the micrometer installed on the measuring rod touches the piano wire, the earphone wire is connected, and the earphone emits a sideways sound. At this time, the micrometer reading is the relative distance of the measuring point. However, the traditional method has problems such as low manual measurement accuracy and poor repeatability; the center measurement calculation method is simple; and the measuring rod has poor applicability. To this end, the present invention comprehensively considers the above-mentioned influences and proposes a new method for center measurement and adjustment calculation of a hydropower station set.

[0051] The present invention measures whether the center of the circular base 10 coincides with the piano wire 2 based on the vertical center line formed by the centring device 1, the piano wire 2 and the weight 3.

[0052] Figure 1 As shown, an extension rod 7 is pulled out from the measuring rod 5 to form a measuring bracket and fixed with a positioning screw 6. A connecting rod 8 is provided at the end of the extension rod 7 to fix the light baffle 4. A laser displacement sensor 9 is also installed at the end of the extension rod 7. The laser displacement sensor 9 and the light baffle 4 form a measuring component, and the distance between the two should be within the measuring range of the laser displacement sensor 9.

[0053] The measurement points are arranged as follows Figure 2 As shown, 8 measuring points are evenly distributed in the circular base to be measured.

[0054] In order to avoid data deviation in the central measurement of the hydropower station unit mentioned in the present invention, the abnormal data analysis method proposed is as follows:

[0055] By adjusting the positioning screw 6, the length of the extension rod 7 is determined to ensure that when the measuring rod 5 and the laser displacement sensor 9 scan over the piano wire 2, the laser displacement sensor can read data. That is, on the one hand, the diameter of the piano wire 2 is 0.3mm, and the spot area of ​​the laser displacement sensor 9 should be less than 0.2mm^2; on the other hand, the distance between the piano wire 2 and the laser displacement sensor 9 should be within the measurement range of the laser displacement sensor.

[0056] The center measurement of the circular base 10 is generally performed at 8 evenly distributed measurement points on the circular base, and the angle between the connected measurement points and the center of the circle is 45°; the laser displacement sensor 9 is driven by the measuring rod 5 to measure the corresponding data at each measurement point in turn, and 8 measurement data constitute a group of data. The center measurement of the circular base can be performed at least 3 groups each time.

[0057] For the data measured by the laser displacement sensor 9, the abnormal data analysis can be used to read and determine the data to be measured. The specific method is as follows: when the laser displacement sensor 9 sweeps over the piano wire 2, the reading of the laser displacement sensor 9 is the relative distance between the laser displacement sensor 9 and the light baffle 4, and the distance is a certain value. When the laser displacement sensor 9 sweeps over the piano wire 2, the reading of the laser displacement sensor 9 changes suddenly, and the sudden change is the relative distance between the laser displacement sensor 9 and the piano wire 2.

[0058] In actual operation, using the principle that the straight line between two points is the shortest, at the same measuring point, the measuring rod 5 can be operated to drive the laser displacement sensor 9 to repeatedly pass over the piano wire 2, and the minimum value is taken as the final measured data of the point.

[0059] The data to be measured at the measuring point can be determined by using data anomaly analysis: Assuming that the relative distance between the laser displacement sensor 9 and the light shield 4 is A, and all data sets measured at the measuring point are C, the actual data B of the measuring point can be extracted using the minimum value rule:

[0060] B=min(C)

[0061] The center measurement adjustment calculation method involved in the present invention mainly comprises the following steps:

[0062] Assume that D groups of data are measured for the circular base 10 , each group has N=8 data, corresponding to 8 evenly distributed points on the circular base 10 .

[0063] First, the 95% confidence level is used to analyze the data in group D. ij (i∈[1N],j∈[1D]) should meet the following requirements:

[0064]

[0065] Then the B ij The measured mean value of the circular base 10 at the i-th point is obtained by using the average calculation method based on the reliable data. If it does not meet the above formula, the data measurement is considered to be wrong and should be re-measured. At the same time, this method can also indicate in real time which measurement points have unreasonable data, providing reference opinions for the next data measurement.

[0066] Secondly, if the center of the circular base 10 to be measured does not coincide with the piano wire 2, there will be an obvious accumulation effect in the measured data of the 8 points to be measured, that is, the data of at least 3 points are smaller, and the data of the other points are larger.

[0067] Set Mean If the difference between the maximum and minimum values ​​is less than or equal to 0.02 mm, it is considered that the center of the circular base 10 coincides with the piano wire 2;

[0068] when When , the data to be tested is considered to be in a classified state, and the next step of adjustment calculation can be performed. Where B′ represents the smallest of the three The mean of Represents 8 The above data limits are proposed based on the power plant maintenance specifications and actual operation feasibility.

[0069] If the above conditions are not met, it is considered that the distribution of the data to be measured is unreasonable and there are abnormal data, which needs to be re-measured and confirmed.

[0070] when When each measurement value B i Decompose it and calculate its components in the plane coordinate system:

[0071]

[0072] The measuring points on the circular base 10 are on the same circumference, and the measured B i The reason for the difference is that the center of the circular base 10 does not coincide with the piano wire 2. Therefore, taking the projection of the piano wire 2 on the plane of the circular base 10 as the origin, each measuring point should conform to the following formula:

[0073] (x i -E) 2 +(y i -F) 2 =R 2

[0074] The above formula represents a typical circle formula, where (E, F) is the center of the circle base 10 with the projection of the piano wire 2 on the plane of the circle base 10 as the origin.

[0075]

[0076] When all δ i When the derivatives of α, β, and γ are zero, the error is the smallest. For the convenience of calculation, δ i 2 Construct a new function and then find the derivatives of α, β, and γ according to the following formula.

[0077]

[0078] Then the eccentricity (E1, F1) can be calculated as follows;

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] Then the offset coordinates between the center of the circular base and the projection point of the piano line are (E2, F2), and the circular base to be measured is adjusted according to the offset coordinates.

[0085] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for measuring the center of a hydropower station unit, characterized in that: The method comprises the following steps: step 1: setting eight measuring points on a circular base and making the angle between two adjacent measuring points and the line connecting the center of the circle be 45°; step 2: passing a vertical center line composed of a centring device, a piano wire and a weight through the center of the circular base; step 3: scanning the piano wire with a laser displacement sensor in a measuring component, the laser displacement sensor can read data, and the measuring component measures corresponding data at each measuring point in turn; step 4: analyzing the data measured by the measuring component using abnormal data; The measuring component comprises a measuring rod, an extension rod, a light shield and a laser displacement sensor; the extension rod is inserted into the measuring rod at one end and fixed by a positioning screw; the laser displacement sensor is installed at the end of the extension rod away from the measuring rod, and the end of the extension rod is also fixed to the light shield by a connecting rod; the laser displacement sensor and the light shield form a measuring unit, and the distance between the two should be within the measuring range of the laser displacement sensor; the measuring method of the measuring component is: the length of the extension rod is determined by adjusting the positioning screw to ensure that when the measuring rod and the laser displacement sensor sweep over the piano wire, the laser displacement sensor can read data; The specific method of abnormal data analysis is: when the laser displacement sensor has not swept across the piano wire, the laser displacement sensor reading is the relative distance between the laser displacement sensor and the light baffle, and this distance is a certain value. When the laser displacement sensor sweeps across the piano wire, the laser displacement sensor reading will suddenly change, and this sudden change is the relative distance between the laser displacement sensor and the piano wire. The data to be measured at the measuring point can be determined by data anomaly analysis. In actual operation, the principle of the shortest straight line between two points is used. At the same measuring point, the laser displacement sensor repeatedly sweeps across the piano wire and takes the minimum value as the final measured data of the measuring point.

2. The method for measuring the center of a hydropower station unit according to claim 1, characterized in that: Eight measurement data measured by the measuring component at eight measurement points constitute a set of data, and at least three sets are measured.

3. The method for measuring the center of a hydropower station unit according to claim 1, characterized in that: The diameter of the piano wire is 0.3 mm, and the spot area of ​​the laser displacement sensor should be less than 0.2 mm^2.

4. A method for calculating the center measurement and adjustment of a hydropower station unit, characterized in that: The data for adjustment calculation is the measurement data obtained according to the method for measuring the center of the hydropower station unit according to any one of claims 1 to 3, and specifically comprises the following steps: Assume that D groups of data are measured for the circular base, each group has N = 8 data, corresponding to 8 evenly distributed points on the circular base; First, the 95% confidence level is used to analyze the data in group D. ij , where i∈[1N], j∈[1D], should satisfy the following two conditions. First, it should satisfy the following formula 1: Then the B ij The reliable data is used to obtain the measured mean value of the circular base at the i-th point by using the average calculation method based on the reliable data. If it does not meet the above formula 1, the data measurement is considered to be incorrect and should be re-measured; Second, if the center of the circular base to be measured does not coincide with the piano wire, there will be an obvious accumulation effect in the measured data of the 8 points to be measured, that is, the data of at least 3 points are smaller, and the data of the others are larger; Set Mean If the difference between the maximum and minimum values ​​is less than or equal to 0.02 mm, the center of the circular base is considered to coincide with the piano wire; The mean value of each measurement point If the following formula 2 is met, the measured data is considered to be in a classified state and the next step of adjustment calculation can be performed; In formula 2, B′ represents the smallest 3 The mean of Represents 8 The mean of If it does not meet Formula 2, it is considered that the distribution of the measured data is unreasonable, there are obvious measurement errors, and it is necessary to re-measure and confirm; After the above two conditions are met, each measured value can be Decompose it and calculate its components in the plane coordinate system: Each measuring point on the circular base is on the same circumference, and the measured The reason for the difference is that the center of the circular base does not coincide with the piano wire. Therefore, taking the projection of the piano wire on the plane of the circular base as the origin, each measuring point should conform to the following formula: (x i -E) 2 +(y i -F) 2 =R 2 ; The formula represents a typical circle formula, (E, F) for which the projection of the piano wire on the plane of the circle base is the center of the circle base as the origin; according to the least squares principle, the distance between each measuring point and the center of the fitting circle should satisfy the following formula: When all δ i When the derivatives of α, β, and γ are zero, the error is the smallest; for convenience of calculation, δ i 2 Construct a new function and then find the derivatives of α, β, and γ as follows; Then the eccentricity can be calculated as follows, recorded as (E1, F1); Then the offset coordinates between the center of the circular base and the projection point of the piano line are (E2, F2), and the circular base to be measured is adjusted according to the offset coordinates.

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