A method for detecting displacement by means of a double-channel combined series connection of eddy current sensors

Abstract

The application discloses a kind of electric eddy current sensor double-channel joint series connection measurement displacement channel detection method, including steps:1) the installation of sensor: shaft displacement sensor and expansion difference sensor;2) implementation detection: displacement display numerical value is measured at shaft displacement measuring point, and expansion difference display numerical value is measured at expansion difference measuring point;3) detection result and qualified determination: according to the recorded standard instrument indication and actual measurement value, then there is the relative or absolute error of shaft displacement and expansion difference measuring point;When each measuring point calibration result is within the maximum allowable error, then it indicates that steam turbine monitoring system is normal;When the calibration result of a certain measuring point exceeds the tolerance, it indicates that the error at the measuring point is generated at TSI cabinet or DCS link, continue to further investigate.The application can detect single electric eddy current sensor and its measurement channel, and can also detect two electric eddy current sensors and their measurement channels of double-channel joint series connection measurement.

Description

Technical Field

[0001] This invention relates to a method for detecting displacement channels using a dual-channel combined series eddy current sensor, which is used in a turbine supervisory instrument (TSI) system to measure rotor axial displacement, rotor relative expansion, and the detection of the complete measurement channels. Background Technology

[0002] In thermal power plants, monitoring the mechanical operating status of the turbine generator set's shaft system is directly related to the safe and economical operation of the unit. Shaft system status monitoring is performed by the TSI system, primarily monitoring parameters such as shaft vibration, rotor axial displacement, the relative expansion difference between the turbine rotor and cylinder (commonly known as differential expansion), and rotational speed. Among these, axial displacement and differential expansion are the main parameters involved in displacement measurement. With the increasing size of rotating machinery, the displacement measurements required are also gradually increasing. Due to limitations in sensor technology development, various non-contact sensors can no longer meet the needs of large measurement ranges. To use sensors with smaller ranges to measure a larger range, dual-channel combined series displacement measurement is applied to the position measurement of large rotating machinery, such as the Emerson MMS6210 measurement module in Tandem mode.

[0003] The axial displacement of steam turbine generator sets is relatively small, and a single eddy current sensor can usually complete the measurement task. However, the measurement range of differential expansion is often relatively large. Due to limitations such as sensor diameter, rotor measurement target surface design and processing, and sensor measurement range, differential expansion measurement of some large units cannot be achieved using a single eddy current sensor. Instead, the measurement ranges of two eddy current sensors are connected in series to achieve differential expansion measurement in a relay manner.

[0004] Differential expansion, or the difference between rotor expansion and cylinder expansion, can cause friction between the rotor blades and cylinder ends if the measured differential expansion exceeds the limit. This can lead to severe vibrations in the unit, endangering the safety of the rotor blades and related shaft accessories, affecting the unit's service life, and even damaging the equipment. Therefore, accurate differential expansion measurement and stable and reliable system performance are crucial for ensuring the safe operation of the generator set.

[0005] According to the latest industry requirements, during unit overhauls, power generation companies should send TSI system sensors to a qualified laboratory for metrological verification and conduct on-site testing of the entire measurement channel, including signal input transmission circuits, measurement modules, signal output circuits, and inter-system transmission. However, currently available eddy current displacement sensor testing devices can only test a single eddy current sensor; they cannot simultaneously test two series-connected eddy current sensors and their measurement channels. Testing two series-connected eddy current sensors separately contradicts the principle of series-connected expansion measurement and cannot accurately assess the accuracy of the expansion measurement channel's test results. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that currently available static detection devices for eddy current displacement sensors can only detect a single eddy current sensor and cannot detect two eddy current sensors connected in series and their measurement channels. This invention provides a method for detecting the displacement channel of a dual-channel eddy current sensor in series. This method can detect both a single eddy current sensor and its measurement channel, as well as two eddy current sensors connected in series and their measurement channels.

[0007] The present invention is achieved using the following technical solution:

[0008] A method for measuring displacement channel detection using a dual-channel tandem eddy current sensor includes the following steps:

[0009] 1) Sensor Installation

[0010] A shaft displacement sensor is installed on the sensor mounting bracket. The gap of a single shaft displacement sensor is adjusted by the crank of a digital dial indicator. Two differential expansion sensors are installed on the sensor mounting bracket, and the gap between the two differential expansion sensors is adjusted by an adjustment device.

[0011] 2) Perform calibration

[0012] A predetermined standard displacement is generated by a digital dial indicator. The displacement and differential expansion sensors are measured at the corresponding measuring points to obtain the displacement and differential expansion values. The values ​​are then processed by the measurement module and displayed or transmitted remotely.

[0013] 3) Calibration results and pass / fail criteria

[0014] Based on the recorded standard instrument readings and actual measured values, the relative or absolute errors of the shaft displacement and differential expansion measurement channels are expressed as follows:

[0015] Or e = X - X0

[0016] in:

[0017] er —Relative error of the axial displacement and differential expansion measurement channel, %;

[0018] e—Absolute error of the shaft displacement and differential expansion measurement channel, mm;

[0019] X0—The given standard value for the axial displacement and differential expansion measurement channel, in mm;

[0020] The actual measured value of the X-axis displacement and differential expansion measurement channel, in mm;

[0021] Referring to DL / T 1012-2006 "Acceptance Test Procedure for Steam Turbine Monitoring and Protection System in Thermal Power Plant" and GB / T13399-2012 "Technical Conditions for Steam Turbine Safety Monitoring Device", the technical specifications for shaft displacement and differential expansion measurement points in the TSI system are as follows: shaft displacement and differential expansion are absolute errors. When the test results of each measurement point are within the maximum permissible error, it indicates that the steam turbine monitoring system is operating normally. When the test result of a certain measurement point exceeds the permissible error, it indicates that the error at that measurement point occurs in the TSI cabinet or DCS link, and further investigation is required.

[0022] A further improvement of the present invention is that the method is capable of detecting a single eddy current sensor and its measurement channel.

[0023] A further improvement of the present invention is that the method is capable of detecting two eddy current sensors and their measurement channels in series.

[0024] A further improvement of this invention is that, in step 3), the industry standard specifies the following technical requirements for the shaft displacement and expansion difference measurement points in the TSI system:

[0025]

[0026] A further improvement of the present invention is that the adjustment device includes a metal spherical gimbal.

[0027] A further improvement of the present invention is that the digital micrometer is fixed to the digital micrometer fixing bracket under the base plate by the fixing screw of the digital micrometer fixing bracket.

[0028] A further improvement of the present invention is that the contraction axis of the digital dial indicator is connected to the measuring target surface.

[0029] A further improvement of this invention is that the measuring target surface reciprocates linearly along the linear bearing under the traction of the digital dial indicator.

[0030] A further improvement of the present invention is that the sensor mounting bracket can perform linear reciprocating motion along the guide linear bearing fixed on the base plate under the traction of the adjustment device.

[0031] The present invention has at least the following beneficial technical effects:

[0032] A deviation value is obtained by applying a high-accuracy standard physical quantity value (static displacement value in mm) to the input terminals of the shaft displacement and differential expansion sensors and comparing it with the value displayed on the DCS (Distributed Control System) / ETS (Turbine Trip Protection System) screen. This deviation value is then used to evaluate the measurement accuracy and reliability of the TSI system by conducting full-process testing of each measurement channel of the shaft displacement / differential expansion in the field; verifying the accuracy of the shaft displacement / differential expansion signal channels, alarms, and trip action values; and ensuring the normal operation of the mechanical operating parameter monitoring system for the turbine generator set and main auxiliary equipment, thus guaranteeing the safe operation of the unit. This deviation value can be used to determine the pass / fail status of the TSI system's measurement parameters. Its technical specifications refer to DL / T 1012-2006 "Acceptance Test Procedure for Steam Turbine Monitoring and Protection System in Thermal Power Plants".

[0033] This invention provides a method for detecting displacement channels using a dual-channel combined series measurement method for eddy current sensors. This method can detect both a single eddy current sensor and its measurement channel, as well as two eddy current sensors connected in series and their measurement channels. The detection device consists of two layers. When detecting a single eddy current sensor and its measurement channel, the upper layer is used only to fix the sensor, with the gap adjusted by the lower layer. When detecting two eddy current sensors connected in series and their measurement channels, the upper layer is used to adjust the gap between the two eddy current sensors and the measurement target surface. The target surface is moved using a digital dial indicator on the lower layer, with one eddy current sensor moving closer to the target surface and the other moving further away. The two eddy current sensors move synchronously, thus enabling the detection of two eddy current sensors connected in series and their measurement channels. Attached Figure Description

[0034] Figure 1 This is a top view of the displacement channel detection method for dual-channel joint series measurement of eddy current sensor according to the present invention.

[0035] Figure 2 This is a left view of the displacement channel detection method for dual-channel joint series measurement of eddy current sensor according to the present invention.

[0036] Figure 3 This is a schematic diagram of the detection signal transmission node.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1-Digital micrometer, 2-Digital micrometer mounting bracket, 3-Measuring target surface, 4-Linear bearing, 5-Sensor mounting bracket, 6-Adjustment device (including metal ball universal head), 7-Guide linear bearing, 8-Base plate, 9-Base plate bracket fixing screw, 10-Base plate bracket, 11-Digital micrometer mounting bracket fixing screw, 12-Linear bearing fixing screw. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1 , Figure 2 , Figure 3 The specific embodiments of the present invention will be further described below.

[0040] This invention provides a method for measuring displacement channels using a dual-channel combined series eddy current sensor, divided into upper and lower layers with the base plate 8 as the boundary. For example... Figure 1 , Figure 2 As shown, the digital micrometer 1 is fixed to the digital micrometer mounting bracket 2 below the base plate 8 by the digital micrometer mounting bracket fixing screw 11. The measuring target surface 3 is connected to the contraction shaft of the digital micrometer 1. The base plate bracket 10 is fastened to the base plate 8 by the base plate bracket fixing screw 9, together forming the lower layer of the present invention. The linear bearing 4 used for guiding the linear motion of the measuring target surface is fastened to the base plate 8 by the linear bearing fixing screw 12. Under the traction of the digital micrometer 1, the measuring target surface 3 makes linear reciprocating motion along the linear bearing 4. The sensor mounting bracket 5 makes linear reciprocating motion along the guide linear bearing 7 fixed on the base plate 8 under the traction of the adjustment device 6, adjusting the gap between the sensor and the measuring target surface 3, together forming the upper layer of the present invention.

[0041] The present invention provides a method for measuring displacement channel detection using a dual-channel combined series connection of an eddy current sensor, comprising the following steps:

[0042] 1) Sensor Installation

[0043] A shaft displacement sensor is installed on the sensor mounting bracket 5. The gap of a single shaft displacement sensor is adjusted by cranking a digital dial indicator. Two differential expansion sensors are installed on the sensor mounting bracket 5. The gap between the two differential expansion sensors is adjusted by adjusting the device 6.

[0044] 2) Detection

[0045] The predetermined standard displacement is generated by the digital dial indicator 1. The displacement and differential expansion sensor are measured at the corresponding measuring points by the shaft displacement sensor and the differential expansion sensor to obtain the displacement and differential expansion display values. After processing by the measurement module, the values ​​are displayed or transmitted remotely.

[0046] 3) Test results and pass / fail criteria

[0047] Based on the recorded standard instrument readings and actual measured values, the relative or absolute errors of the shaft displacement and differential expansion measurement channels are expressed as follows:

[0048] Or e = X - X0

[0049] in:

[0050] e r —Relative error of the axial displacement and differential expansion measurement channel, %;

[0051] e—Absolute error of the shaft displacement and differential expansion measurement channel, mm;

[0052] X0—The given standard value for the axial displacement and differential expansion measurement channel, in mm;

[0053] The actual measured value (mm) of the X-axis displacement and differential expansion measurement channel.

[0054] Referring to DL / T 1012-2006 "Acceptance Test Procedure for Steam Turbine Monitoring and Protection System in Thermal Power Plant" and GB / T13399-2012 "Technical Conditions for Steam Turbine Safety Monitoring Device", the technical specifications for shaft displacement and differential expansion measurement points in the TSI system are as follows: shaft displacement and differential expansion are absolute errors. When the test results of each measurement point are within the maximum permissible error, it indicates that the steam turbine monitoring system is operating normally. When the test result of a certain measurement point exceeds the permissible error, it indicates that the error at that measurement point occurs in the TSI cabinet or DCS link, and further investigation is required.

[0055] This invention is a method for detecting displacement channels of dual-channel combined series measurement using eddy current sensors. It can detect a single eddy current sensor and its measurement channel, as well as two eddy current sensors and their measurement channels connected in series.

[0056] In step 2), a high-precision dial indicator generates a standard physical quantity. Its accuracy is much higher than that of the dial indicator used in traditional testing devices and the signal generator which is greatly affected by environmental factors. It can more accurately quantify the system error of the measurement channel. Moreover, the equipment is portable, easy to operate and learn, and the error introduced by operation is small.

[0057] In step 3), the industry standard specifies the following technical requirements for shaft displacement and differential expansion measurement points in the TSI system:

[0058]

[0059] The above description is merely the basic principle of the present invention and does not constitute any limitation on the present invention. Any equivalent changes and modifications made to the present invention based on the present invention are within the scope of protection of this patent technology.

Claims

1. A method for measuring displacement channel detection using a dual-channel combined series connection of an eddy current sensor, characterized in that, Includes the following steps: 1) Sensor Installation A shaft displacement sensor is installed on the sensor mounting bracket. The gap of a single shaft displacement sensor is adjusted by the crank of a digital dial indicator. Two differential expansion sensors are installed on the sensor mounting bracket, and the gap between the two differential expansion sensors is adjusted by the adjustment device. The digital dial indicator is fixed to the digital dial indicator mounting bracket under the base plate by the mounting screw of the digital dial indicator mounting bracket. 2) Perform calibration A predetermined standard displacement is generated by a digital dial indicator. The displacement and differential expansion sensors are measured at the corresponding measuring points to obtain the displacement and differential expansion values. The values ​​are then processed by the measurement module and displayed or transmitted remotely. 3) Calibration results and pass / fail criteria Based on the recorded standard instrument readings and actual measured values, the relative or absolute errors of the shaft displacement and differential expansion measurement channels are expressed as follows: or in: e r —Relative error of the axial displacement and differential expansion measurement channels, % e —Absolute error of the axial displacement and differential expansion measurement channel, mm; X 0 — The given standard value for the axial displacement and differential expansion measurement channel, in mm; X — Actual measured values ​​of shaft displacement and differential expansion measurement channels, in mm; Referring to DL / T 1012-2006 "Acceptance Test Procedure for Steam Turbine Monitoring and Protection System in Thermal Power Plant" and GB / T13399-2012 "Technical Conditions for Steam Turbine Safety Monitoring Device", the technical specifications for shaft displacement and differential expansion measurement points in the TSI system are as follows: shaft displacement and differential expansion are absolute errors. When the test results of each measurement point are within the maximum permissible error, it indicates that the steam turbine monitoring system is operating normally. When the test result of a certain measurement point exceeds the permissible error, it indicates that the error at that measurement point occurs in the TSI cabinet or DCS link, and further investigation is required. Industry standards specify the following technical requirements for shaft displacement and differential expansion measurement points in the TSI system: 。 2. The method for detecting displacement channels using a dual-channel combined series measurement of an eddy current sensor according to claim 1, characterized in that, This method can detect a single eddy current sensor and its measurement channel.

3. The method for detecting displacement channels using a dual-channel combined series measurement of an eddy current sensor according to claim 1, characterized in that, This method can detect two eddy current sensors and their measurement channels in series.

4. The method for detecting displacement channels using a dual-channel combined series measurement of an eddy current sensor according to claim 1, characterized in that, The adjustment device includes a metal spherical gimbal.

5. The method for detecting displacement channels using a dual-channel combined series measurement of an eddy current sensor according to claim 1, characterized in that, The shrinkage axis of the digital dial indicator is connected to the measuring target surface.

6. The method for detecting displacement channels using a dual-channel combined series measurement of an eddy current sensor according to claim 5, characterized in that, The measuring target surface reciprocates linearly along the linear bearing under the traction of the digital dial indicator.

7. The method for detecting displacement channels using a dual-channel combined series measurement of an eddy current sensor according to claim 5, characterized in that, The sensor mounting bracket can reciprocate linearly along the guide linear bearing fixed on the base plate under the traction of the adjustment device.

Images