An instantaneous hydraulic hammer device and a test system and method based on the device

Abstract

The invention discloses an instantaneous hydraulic hammer device and a test system and method based on the device, comprising a nitrogen chamber, a hydraulic cylinder, a piston, an accumulator, a reversing valve, a piston rod, a push rod, a force hammer and a positioning base; wherein the piston is located in the hydraulic cylinder, and the hydraulic cylinder is divided into a first chamber, a second chamber, a third chamber and a fourth chamber of the piston from top to bottom, the lower end of the piston is connected to the upper end of the piston rod, the lower end of the piston rod is directly opposite to the upper end of the force hammer, the lower end of the push rod is inserted into the hydraulic cylinder and connected to the upper end of the piston, and the upper end of the push rod is inserted into the nitrogen chamber; an annular groove is provided in the middle of the piston, and the outer walls on both sides of the piston are in contact with the inner wall of the hydraulic cylinder; a main valve core is provided in the reversing valve, wherein the reversing valve is divided into an upper chamber and a lower chamber by the main valve core, the device can realize automatic control of force hammering, and the system and method have the characteristics of high test efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of dynamic characteristic detection of generator stator winding ends, and relates to an instantaneous hydraulic hammer device and a test system and method based on the device. Background Art

[0002] During the normal operation of large steam turbine generators, the stator ends will be subjected to electromagnetic excitation force of double frequency (100Hz). If the natural frequency of the stator winding ends is close to 100Hz, resonance will occur and produce a large resonance amplitude, which may cause the stator structure to loosen, the wire rod insulation to wear, and even breakage due to excessive amplitude, which seriously threatens the safe operation of the unit. Therefore, the measurement and evaluation of the stator end characteristics of the generator is of great significance to the safe and stable operation of the generator.

[0003] The dynamic characteristics test of the stator end should be carried out before the steam turbine generator leaves the factory, when the new machine is handed over, when abnormal conditions occur during operation, and during overhaul inspection. The dynamic characteristics test of the stator end is carried out by hammering the stator winding measuring point position with a manual force hammer. Hammering is one of the important links in the test and detection work. Generally, the method of multi-point excitation and one-point vibration pickup is adopted. It is required that the waveform of multiple hammering has good feedback, and each stator winding measuring point position should not be less than 3 valid signals. The traditional manual handheld hammer has the following problems: 1. There are many stator winding measuring point positions in the dynamic test of the stator winding end of the synchronous generator. For a 2-pole generator, the total number of measuring points on the excitation side and the steam side is not less than 64; for a 4-pole generator, the total number of measuring points on the excitation side and the steam side is not less than 128. The work intensity of the test hammer personnel is huge. 2. When using the manual hammering method, the size of the hammering force, the verticality of the hammer drop, the drop distance and the hammering position are not easy to control, which affects the waveform feedback of the hammering signal, thereby reducing the accuracy of further data analysis of the software. 3. Due to the problems of working environment and hammering angle, the number of manual hammering errors is high, which greatly reduces the test efficiency and prolongs the working time. Therefore, it is very necessary to develop a new test method to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide an instantaneous hydraulic hammer device and a test system and method based on the device. The device can realize automatic control of force hammer hammering, and the system and method have the characteristics of high test efficiency.

[0005] To achieve the above-mentioned purpose, the instantaneous hydraulic hammering device of the present invention comprises a nitrogen chamber, a hydraulic cylinder, a piston, an accumulator, a reversing valve, a piston rod, a push rod, a hammer and a positioning base;

[0006] The piston is located in the hydraulic cylinder, and the hydraulic cylinder is divided into chambers 1, 2, 3 and 4 of the piston from top to bottom. The lower end of the piston is connected to the upper end of the piston rod, and the lower end of the piston rod faces the upper end of the hammer. The lower end of the push rod is inserted into the hydraulic cylinder and then connected to the upper end of the piston. The upper end of the push rod is inserted into the nitrogen chamber.

[0007] An annular groove is provided in the middle of the piston, and the outer walls on both sides of the piston are in contact with the inner wall of the hydraulic cylinder;

[0008] A main valve core is arranged in the reversing valve, wherein the reversing valve is divided into an upper chamber and a lower chamber by the main valve core;

[0009] The upper chamber is connected with chamber 1 of the piston, the energy accumulator and chamber 4 of the piston, the lower chamber is connected with chamber 2 of the piston and chamber 3 of the piston, the upper chamber, chamber 4 of the piston and chamber 1 of the piston are connected with the high-pressure oil chamber through a high-pressure oil pipe, and chamber 3 of the piston, chamber 4 of the piston, chamber 2 of the piston, the lower chamber and chamber 1 of the piston are connected with the oil return chamber.

[0010] The main valve core is distributed obliquely.

[0011] The end dynamic characteristic test system based on instantaneous hydraulic hammering technology of the present invention comprises a dynamic signal analyzer, an acceleration sensor, a force sensor and an instantaneous hydraulic hammering device, wherein the force sensor is arranged on the force hammer, the acceleration sensor is fixed at the measuring point position of the stator end, and the lower end of the force hammer is directly opposite to the measuring point position of the stator end;

[0012] The output end of the acceleration sensor and the output end of the force sensor are connected to the dynamic signal analyzer.

[0013] The output end of the acceleration sensor and the output end of the force sensor are connected to the dynamic signal analyzer via a signal charge amplifier.

[0014] The end dynamic characteristics test method based on instantaneous hydraulic hammering technology of the present invention comprises the following steps:

[0015] The measuring point position of the stator end is hammered by an instantaneous hydraulic hammer device, the hammer force signal of the force hammer is measured by a force sensor, and the acceleration signal of the measuring point position of the stator end is obtained by an acceleration sensor. The acceleration signal and the hammer force signal are amplified by a signal charge amplifier and input into a dynamic signal analyzer to form a set of excitation response data, and multiple sets of excitation response data are obtained by hammering the measuring points multiple times with the force hammer;

[0016] A frequency response function is constructed according to the multiple groups of excitation response data, and curve fitting is performed according to the frequency response function to obtain natural frequencies, vibration shapes and modal masses of each order, and the stator end characteristics of the generator are evaluated according to the natural frequencies, vibration shapes and modal masses of each order.

[0017] The present invention has the following beneficial effects:

[0018] The instantaneous hydraulic hammer device and the test system and method based on the device described in the present invention change the traditional way of hammering the measuring points with a handheld hammer during specific operation, and use the instantaneous hydraulic hammer device to hammer the measuring points at the end of the stator, effectively reducing the work intensity of the hammering personnel in the traditional test, reducing manpower, and reducing the hammering errors caused by the hammering personnel due to site problems, effectively improving work efficiency, and reducing the test time. In addition, the weight, verticality, and drop distance of the hammer can be controlled through the automation device, and the accurate collection of the hammering force is completed, effectively improving the accuracy of data collection and analysis in the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a system structure diagram of the present invention;

[0020] Figure 2 It is a structural diagram of the instantaneous hydraulic hammer device;

[0021] Figure 3 This is a working process diagram of the instantaneous hydraulic hammer device return acceleration;

[0022] Figure 4 This is a working process diagram of the return brake of the instantaneous hydraulic hammer device;

[0023] Figure 5 It is a working process diagram of the stroke acceleration of the instantaneous hydraulic hammer device;

[0024] Figure 6 It is a working process diagram of the piston striking of the instantaneous hydraulic hammer device;

[0025] Figure 7 Figure 2 is the location diagram of the measurement points for the overall modal test of the stator winding end. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0027] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0028] refer to Figure 2 , the instantaneous hydraulic hammering device of the present invention comprises a nitrogen chamber, a hydraulic cylinder, a piston, an accumulator, a valve control system, a hammer and a positioning base;

[0029] The piston is located in the hydraulic cylinder, and the hydraulic cylinder is divided into chambers 1, 2, 3 and 4 of the piston from top to bottom. The lower end of the piston is connected to the upper end of the piston rod, and the lower end of the piston rod faces the upper end of the hammer. A force sensor is arranged in the hammer. The lower end of the push rod is inserted into the hydraulic cylinder and then connected to the upper end of the piston. The upper end of the push rod is inserted into the nitrogen chamber.

[0030] An annular groove is provided in the middle of the piston, and the outer walls on both sides of the piston are in contact with the inner wall of the hydraulic cylinder;

[0031] A main valve core is arranged in the reversing valve, wherein the reversing valve is divided into an upper chamber and a lower chamber by the main valve core;

[0032] The upper chamber is connected with chamber 1 of the piston, the energy accumulator and chamber 4 of the piston, the lower chamber is connected with chamber 2 of the piston and chamber 3 of the piston, the upper chamber, chamber 4 of the piston and chamber 1 of the piston are connected with the high-pressure oil chamber through a high-pressure oil pipe, and chamber 3 of the piston, chamber 4 of the piston, chamber 2 of the piston, the lower chamber and chamber 1 of the piston are connected with the oil return chamber.

[0033] refer to Figure 1 , the end dynamic characteristics test system based on instantaneous hydraulic hammering technology of the present invention comprises an acceleration sensor, a force sensor and an instantaneous hydraulic hammering device;

[0034] The acceleration sensor is fixed at a measuring point position at the end of the stator, and the lower end of the force hammer is directly opposite to the measuring point position at the end of the stator.

[0035] The output end of the acceleration sensor and the output end of the force sensor are connected to the input end of the signal charge amplifier, and the output end of the signal charge amplifier is connected to the dynamic signal analyzer.

[0036] The working process of the instantaneous hydraulic hammer device is as follows:

[0037] The instantaneous hydraulic hammer device includes the return acceleration working process, return braking working process, stroke acceleration working process and piston striking working process, specifically:

[0038] Reference for return acceleration process Figure 3 At the beginning of this stage, the hammer is in a momentary pause state. At this time, the hydraulic oil enters the upper chamber of the reversing valve through the high-pressure oil pipe, making the upper chamber of the reversing valve a high-pressure chamber, and the lower chamber of the reversing valve communicates with the oil return chamber to form a low-pressure chamber, so that the main valve core of the reversing valve is in the lower limit position. At the same time, the hydraulic oil enters the piston chamber 1 through the high-pressure oil pipe, making the piston chamber 1 a high-pressure chamber, and the piston chambers 2, 3 and 4 are connected to the oil return chamber, making the piston chambers 2, 3 and 4 low-pressure chambers. Therefore, under the action of the high-pressure oil in the piston chamber 1, the piston accelerates upward in the return stroke and compresses the nitrogen in the tail nitrogen chamber, making it perform adiabatic compression.

[0039] Reference for return brake working process Figure 4 , the piston continues to make a return motion upward in the upper stage. When the lower edge of the middle section of the piston passes over the lower edge of the upper opening of the piston's chamber 2, the high-pressure oil in the piston's chamber 1 and chamber 2 enters the lower chamber of the reversing valve. At this time, the upper and lower chambers of the reversing valve are filled with high-pressure oil of equal pressure. However, due to the unequal effective areas of the shaft shoulders, the main valve core of the reversing valve is forced to start moving upward. Correspondingly, the return thrust acting on the piston is reduced. At the same time, the return resistance exerted by the compressed nitrogen in the nitrogen chamber above the piston becomes larger and larger, and the return acceleration motion of the piston turns into the braking working process.

[0040] Stroke acceleration working process reference Figure 5 When the main valve core of the reversing valve rises to the 4th chamber of the piston, the high-pressure oil enters the 4th chamber of the piston through the reversing valve, turning the 4th chamber of the piston into a high-pressure chamber. The unequal effective area of ​​the piston shoulder causes a pressure difference at both ends of the piston. At the same time, due to the pressure of the compressed nitrogen in the nitrogen chamber and its own gravity, a strong pressure difference is generated on the piston to drive the piston downward for accelerated impact movement.

[0041] Piston striking working process reference Figure 6 At the end of the upper stage, the piston makes quasi-equiaccelerated motion in the direction of the force hammer under double pressure. When the upper edge of the middle section of the piston passes over the upper edge of the signal hole, the lower chamber of the reversing valve is connected to the oil return pipe, and it starts to move downward under the action of the high-pressure oil in the upper chamber of the reversing valve. At this time, the piston has obtained enough kinetic energy to impact the force hammer, so that the force hammer completes the hammering action on the measuring point, and the main valve core of the reversing valve continues to move to the lower limit position, and the piston is in a pause stage. At this point, the instantaneous hydraulic hammering device completes a working cycle.

[0042] refer to Figure 7The measuring points in the present invention are located on the inner cross-section of the cone at the end of the steam-side and excitation-side windings. During the test, three circles are taken on the steam side and the excitation side respectively. The measuring points of the nose joint at the end of the stator winding constitute circumference 1, the measuring points of the notch at the end of the stator winding constitute circumference 2, and the measuring points in the middle of the involute at the end of the stator winding constitute circumference 3. The positions of the points to be measured are evenly distributed on each circumference. At least 16 measuring points are arranged on each circumference of a 2-pole generator, and at least 32 measuring points are arranged on each circumference of a 4-pole generator. During normal testing, the measuring points on circumference 1 and circumference 2 are generally hammered. According to the needs of the situation, the measuring points on circumference 3 can be added.

[0043] The specific process of the end dynamic characteristics test method based on instantaneous hydraulic hammering technology described in the present invention is as follows:

[0044] Before the test, the turbine generator rotor is taken out and placed outside the chamber, the upper and lower end covers on the steam side and the excitation side are opened and the cover cloth is completely opened; all the generator leads are installed and the manhole door is opened; in order to allow the test personnel to safely enter the generator chamber, a temporary scaffolding needs to be set up.

[0045] The hammer force signal of the force hammer is measured by a force sensor, and the acceleration signal at the measuring point position at the end of the stator is obtained by an acceleration sensor. The acceleration signal and the hammer force signal are amplified by a signal charge amplifier and input into a dynamic signal analyzer. The force hammer is used to hit the measuring point multiple times, so that the dynamic signal analyzer obtains multiple groups of excitation response data, wherein each group of excitation response data includes an acceleration signal and a hammer force signal.

[0046] The dynamic signal analyzer analyzes the relationship between the excitation signal and the response signal to obtain the frequency response function, and performs curve fitting on the obtained frequency response function to obtain the natural frequencies, vibration shapes and modal masses of each order, so that the test personnel can evaluate the characteristics of the generator stator end.

Claims

1. An instantaneous hydraulic hammer device, characterized in that: It includes a nitrogen chamber, a hydraulic cylinder, a piston, an accumulator, a reversing valve, a piston rod, a push rod, a hammer and a positioning base; The piston is located in the hydraulic cylinder, and the hydraulic cylinder is divided into chambers 1, 2, 3 and 4 of the piston from top to bottom. The lower end of the piston is connected to the upper end of the piston rod, and the lower end of the piston rod faces the upper end of the hammer. The lower end of the push rod is inserted into the hydraulic cylinder and then connected to the upper end of the piston. The upper end of the push rod is inserted into the nitrogen chamber. An annular groove is provided in the middle of the piston, and the outer walls on both sides of the piston are in contact with the inner wall of the hydraulic cylinder; A main valve core is arranged in the reversing valve, wherein the reversing valve is divided into an upper chamber and a lower chamber by the main valve core; The upper chamber is connected with chamber 1 of the piston, the energy accumulator and chamber 4 of the piston, the lower chamber is connected with chamber 2 of the piston and chamber 3 of the piston, the upper chamber, chamber 4 of the piston and chamber 1 of the piston are connected with the high-pressure oil chamber through a high-pressure oil pipe, and chamber 3 of the piston, chamber 4 of the piston, chamber 2 of the piston, the lower chamber and chamber 1 of the piston are connected with the oil return chamber.

2. The instantaneous hydraulic hammer device according to claim 1, characterized in that: The main valve core is distributed obliquely.

3. An end dynamic characteristics test system based on instantaneous hydraulic hammering technology, characterized in that: It comprises a dynamic signal analyzer, an acceleration sensor, a force sensor and the instantaneous hydraulic hammer device according to claim 1, wherein the force sensor is arranged on the force hammer, the acceleration sensor is fixed at the measuring point position of the stator end, and the lower end of the force hammer is directly opposite to the measuring point position of the stator end; The output end of the acceleration sensor and the output end of the force sensor are connected to the dynamic signal analyzer.

4. The end dynamic characteristics test system based on instantaneous hydraulic hammering technology according to claim 3 is characterized in that: The output end of the acceleration sensor and the output end of the force sensor are connected to the dynamic signal analyzer via a signal charge amplifier.

5. A method for testing the dynamic characteristics of an end portion based on instantaneous hydraulic hammering technology, characterized in that: The end dynamic characteristics test system based on instantaneous hydraulic hammering technology according to claim 3 comprises the following steps: The measuring point position of the stator end is hammered by an instantaneous hydraulic hammer device, the hammer force signal of the force hammer is measured by a force sensor, and the acceleration signal of the measuring point position of the stator end is obtained by an acceleration sensor. The acceleration signal and the hammer force signal are amplified by a signal charge amplifier and input into a dynamic signal analyzer to form a set of excitation response data, and multiple sets of excitation response data are obtained by hammering the measuring points multiple times with the force hammer; A frequency response function is constructed according to the multiple groups of excitation response data, and curve fitting is performed according to the frequency response function to obtain natural frequencies, vibration shapes and modal masses of each order, and the stator end characteristics of the generator are evaluated according to the natural frequencies, vibration shapes and modal masses of each order.

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