A Generator Rotor Thermal Dynamic Balancing Method Based on Cold and Hot State Fundamental Frequency Vibration

Abstract

The present invention discloses a method for thermal dynamic balancing of a generator rotor based on cold and hot state fundamental frequency vibrations, comprising the following steps: S1, obtaining vibration characteristic information; S2, determining whether the cold state fundamental frequency vibration amplitude is greater than or equal to a set threshold a; if so, determining whether the cold state fundamental frequency vibration phase is in phase with the hot state fundamental frequency vibration phase; if the cold state fundamental frequency vibration phase is in phase with the hot state fundamental frequency vibration phase, then using the method of thermal dynamic balancing to solve the abnormal vibration caused by thermal bending; if not, then proceeding to step S3; S3, determining whether the cold state fundamental frequency vibration phase is out of phase with the hot state fundamental frequency vibration phase; if so, determining whether the hot state fundamental frequency vibration amplitude is less than or equal to a set threshold e; if the hot state fundamental frequency vibration amplitude is less than or equal to the set threshold e, then using the method of thermal dynamic balancing to solve the abnormal vibration caused by thermal bending. The present invention is a method that is easy to implement, has scientific calculations, and accurate diagnosis, effectively solving the problem of poor thermal dynamic balancing effect on site.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration maintenance of rotating machinery, and more particularly to a thermal dynamic balancing method for a generator rotor based on cold and hot state fundamental frequency vibrations. Background Art

[0002] The bending deformation that occurs in a generator rotor after being heated is called thermal bending. Thermal bending will cause a change in the balance state of the rotor, so thermal bending is also called thermal imbalance. Thermal bending is a relatively common vibration phenomenon, and the causes of thermal bending are diverse. When there are defects in the generator rotor such as blocked cooling channels, slight inter-turn short circuits, restricted expansion of the rotor coils, large internal stresses in the rotor, and uneven material quality, after loading, the vibration of the generator shaft bearing will increase with the increase of the excitation current, which will further lead to excessive vibration and affect the safe and stable operation of the unit. To address this problem, on-site thermal dynamic balancing of the generator rotor is often carried out to improve its vibration condition and reduce the vibration to a qualified range. When determining the thermal dynamic balancing scheme for the generator, it is necessary to comprehensively consider the vibration values and phases at cold state and hot state after loading at 3000 r / min.

[0003] Regarding the determination of the thermal dynamic balancing scheme for the generator rotor, existing technical materials such as books and papers only generally state that it is necessary to consider both the cold state and the hot state vibrations at 3000 r / min, but do not specifically explain how to determine the dynamic balancing scheme based on the magnitude and phase relationship of the cold and hot state values. Therefore, when conducting on-site thermal dynamic balancing tests on generator rotors, technicians determine the dynamic balancing scheme based on their own experience, resulting in different effects of thermal dynamic balancing. For senior experts with rich experience in vibration fault diagnosis, thermal dynamic balancing can achieve good results, but for new or inexperienced fault diagnosis personnel, the effect of thermal dynamic balancing will be poor or even ineffective, causing a waste of a large amount of manpower and financial resources.

[0004] Therefore, there is an urgent need for a method that is easy to implement on-site, has scientific calculations, and accurate diagnosis to solve the above technical problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a thermal dynamic balancing method for a generator rotor based on cold and hot state fundamental frequency vibrations, so as to solve the problem that when conducting on-site thermal dynamic balancing tests on generator rotors, technicians only determine the dynamic balancing scheme based on their own experience, resulting in poor effects of thermal dynamic balancing and wasting a large amount of manpower and financial resources.

[0006] To solve the above technical problems, the following technical solutions are adopted in the present invention.

[0007] A thermal dynamic balancing method for a generator rotor based on cold and hot state fundamental frequency vibrations includes the following steps:

[0008] S1. Obtain vibration characteristic information; the vibration characteristic information includes cold-state vibration overall frequency, cold-state fundamental frequency vibration amplitude, cold-state fundamental frequency vibration phase, hot-state vibration overall frequency, hot-state fundamental frequency vibration amplitude, and hot-state fundamental frequency vibration phase;

[0009] S2. Determine whether the cold-state fundamental frequency vibration amplitude is greater than or equal to a set threshold a;

[0010] If so, determine whether the cold-state fundamental frequency vibration phase is in phase with the hot-state fundamental frequency vibration phase; if the cold-state fundamental frequency vibration phase is in phase with the hot-state fundamental frequency vibration phase, use the hot-state dynamic balancing method to solve the abnormal vibration caused by the thermal bending of the generator rotor;

[0011] If not, proceed to step S3;

[0012] S3. Determine whether the cold-state fundamental frequency vibration phase is out of phase with the hot-state fundamental frequency vibration phase;

[0013] If so, determine whether the hot-state fundamental frequency vibration amplitude is less than or equal to a set threshold e; if the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold e, use the hot-state dynamic balancing method to solve the abnormal vibration caused by the thermal bending of the generator rotor;

[0014] If not, determine whether the hot-state fundamental frequency vibration amplitude is less than or equal to a set threshold f; if the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold f, use the hot-state dynamic balancing method to solve the abnormal vibration caused by the thermal bending of the generator rotor;

[0015] Among them, the set threshold a < the set threshold e < the set threshold f.

[0016] To further optimize the technical solution, in step S2, if the cold-state fundamental frequency vibration phase is out of phase with the hot-state fundamental frequency vibration phase, determine whether the cold-state fundamental frequency vibration amplitude is greater than a set threshold b and less than or equal to a set threshold c; if so, proceed to step S221 for judgment, if not, proceed to step S23 for judgment;

[0017] S221. Determine whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold c; if so, use the hot-state dynamic balancing method to perform hot-state dynamic balancing on the rotor;

[0018] S23. Determine whether the cold-state fundamental frequency vibration amplitude is greater than the set threshold c; if not, determine whether the hot-state fundamental frequency vibration amplitude is less than or equal to a set threshold d, if so, use the hot-state dynamic balancing method to perform hot-state dynamic balancing on the rotor;

[0019] Among them, the set threshold a < the set threshold b < the set threshold c < the set threshold d < the set threshold e < the set threshold f.

[0020] Further optimize the technical solution. The method for hot dynamic balance includes the following steps:

[0021] Assume that the cold vibration values of the bearings at both ends A and B of the generator rotor are A 0l , B 0l , and the hot vibration values after loading are A 0r , B 0r ;

[0022] Simultaneously add weights P a , P b at both ends A and B of the generator rotor, with an angular difference of 180°. Measure the cold vibration values at both ends of the generator rotor after adding weights, which are A 1l , B 1l , and the hot vibration values after loading are A 1r , B 1r ;

[0023] Calculate the influence coefficient a A :

[0024]

[0025] Calculate the required weight Q A at end A:

[0026]

[0027] Calculate the residual vibration A s at end A:

[0028] A s = a A Q A + A 0l

[0029] Calculate the required weight Q B at end B.

[0030] Further optimize the technical solution. The required weight Q B at end B is equal in magnitude and opposite in direction to the required weight Q A at end A.

[0031] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is as follows.

[0032] The present invention is a method that is easy to implement, scientifically calculated, and accurately diagnosed, effectively solving the problem of poor on-site hot dynamic balance effect. By determining the hot dynamic balance scheme based on the magnitude and phase relationship of the cold and hot fundamental frequencies of vibration, when abnormal vibration occurs, first obtain the vibration characteristic information of the cold and hot states, and then comprehensively analyze the vibration data of the cold and hot states. Finally, a hot dynamic balance scheme is given. Calculate the required counterweights at both ends of the generator rotor through the hot dynamic balance method to achieve the balance of both ends of the generator rotor, thereby solving the abnormal vibration caused by the thermal bending of the generator rotor. Brief Description of the Drawings

[0033] Figure 1 It is a logic judgment diagram of the present invention. Detailed Implementation Manner

[0034] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0035] A method for hot dynamic balance of a generator rotor based on cold and hot fundamental frequencies of vibration. When abnormal vibration occurs, first obtain the vibration characteristic information of the cold and hot states, and then comprehensively analyze the vibration data of the cold and hot states. Finally, a hot dynamic balance scheme is given. Combining Figure 1 As shown, the present invention includes the following steps:

[0036] S1. Obtain vibration characteristic information.

[0037] When abnormal vibration occurs in the unit, conduct vibration tests, analyze and process the vibration data to obtain the cold-state overall vibration frequency, cold-state fundamental frequency vibration amplitude, cold-state fundamental frequency vibration phase, hot-state overall vibration frequency, hot-state fundamental frequency vibration amplitude, and hot-state fundamental frequency vibration phase. After obtaining the above vibration characteristics, perform the judgment in step S2.

[0038] S2. Judge whether the cold-state fundamental frequency vibration amplitude is greater than or equal to the set threshold a. The set threshold a in this embodiment is 25 μm.

[0039] If so, perform step S21. If it is judged that the cold-state fundamental frequency vibration amplitude is less than the set threshold a, perform step S3.

[0040] S21. Judge whether the cold-state fundamental frequency vibration phase is in phase with the hot-state fundamental frequency vibration phase. If the phase difference between the hot-state fundamental frequency vibration phase and the cold-state fundamental frequency vibration phase is less than 90°, it is considered that the hot-state fundamental frequency vibration phase is in phase with the cold-state fundamental frequency vibration phase. If not, that is, the phase difference between the hot-state fundamental frequency vibration phase and the cold-state fundamental frequency vibration phase is greater than or equal to 90°, it is considered that the hot-state fundamental frequency vibration phase is out of phase with the cold-state fundamental frequency vibration phase.

[0041] If the cold-state fundamental frequency vibration phase is in-phase with the hot-state fundamental frequency vibration phase, the hot-state dynamic balancing method is adopted to solve the abnormal vibration caused by the thermal bending of the generator rotor. When performing the hot-state dynamic balancing calculation, the vibration data in the cold state is used as the basis for calculation, reducing the vibration value in the cold state to the minimum value, or balancing the vibration in the cold state to the opposite phase of the original vibration, with a value less than or equal to 25 μm.

[0042] The method of hot-state dynamic balancing in this step is as follows:

[0043] 1. Assume that the cold-state vibration values of the bearings at both ends A and B of the generator rotor are A 0l , B 0l , respectively, and the hot-state vibration values after loading are A 0r , B 0r ;

[0044] 2. Add weights P a , P b simultaneously at both ends A and B of the generator rotor, with an angular difference of 180° (equal in weight and opposite in angle, i.e., P a = P b ), and measure the cold-state vibration values at both ends of the generator rotor after adding weights, which are A 1l , B 1l , respectively, and the hot-state vibration values after loading are A 1r , B 1r ;

[0045] 3. Calculate the influence coefficient a A . Calculate according to formula (1):

[0046]

[0047] 4. Calculate the required weight Q A at end A. Calculate according to formula (2):

[0048]

[0049] 5. Calculate the residual vibration A s at end A. Calculate according to formula (3):

[0050] A s = a A Q A + A 0l (3)

[0051] Note: Make the residual vibration A s close to 0 in the cold state value, or opposite to A 0l , with a value less than or equal to 25 μm

[0052] 6. Calculate the required weight Q B at end B. QB is equal in magnitude to Q A and opposite in direction.

[0053] If the cold-state fundamental frequency vibration phase is out of phase with the hot-state fundamental frequency vibration phase, then step S22 is performed for judgment.

[0054] S22: Then judge whether the cold-state fundamental frequency vibration amplitude is greater than the set threshold b and less than or equal to the set threshold c. Among them, in this embodiment, the set threshold b is 50 μm, and the set threshold c is 80 μm. If so, perform the judgment of step S221; if not, perform the judgment of step S23.

[0055] S221: Judge whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold c. In this embodiment, the set threshold c is 80 μm. If so, the hot-state dynamic balance method is used to perform hot-state dynamic balance on the rotor. When performing hot-state dynamic balance, the vibration data in the hot state is used as the calculation basis, but adding weights will cause an increase in vibration in the cold state, and the vibration in the cold state needs to be controlled within an acceptable level (the cold-state vibration value is less than or equal to 100 μm). If not, it is difficult to reduce the vibrations in both the cold and hot states to an acceptable level by taking hot-state dynamic balance.

[0056] The hot-state dynamic balance method of step S221 is as follows:

[0057] 1. Assume that the cold-state vibration values of the bearings at both ends A and B of the generator rotor are A 0l and B 0l respectively, and the hot-state vibration values after loading are A 0r and B 0r respectively;

[0058] 2. Add weights P a and P b simultaneously at both ends A and B of the generator rotor, with an angular difference of 180° (equal in weight magnitude and opposite in angle, that is, P a = P b ), and measure the cold-state vibration values of both ends of the generator rotor after adding weights as A 1l and B 1l respectively, and the hot-state vibration values after loading are A 1r and B 1r respectively;

[0059] 3. Calculate the influence coefficient a A . Calculate according to formula (1):

[0060]

[0061] 4. Calculate the required weight Q A at end A. Calculate according to formula (2):

[0062]

[0063] 5. Calculate the residual vibration A at end A s . Calculate according to formula (3):

[0064] A s = a A Q A + A 0l (6)

[0065] Note: Make the residual vibration A s The cold state value is less than or equal to 100 μm.

[0066] 6. Calculate the required counterweight Q at end B B . Q B is equal in magnitude to Q A and opposite in direction.

[0067] S23. Judge whether the vibration amplitude of the cold state fundamental frequency is greater than the set threshold value c. In this embodiment, the set threshold value c is 80 μm. If so, perform thermal dynamic balancing. It is difficult to reduce the vibrations in both the cold and hot states to an acceptable level simultaneously. If not, proceed to step S231 for judgment.

[0068] S231. Judge whether the vibration amplitude of the hot state fundamental frequency is less than or equal to the set threshold value d. In this embodiment, the set threshold value d is 100 μm. If so, use the method of thermal dynamic balancing to perform thermal dynamic balancing on the rotor. When performing thermal dynamic balancing, use the vibration data in the hot state as the calculation basis. However, adding weights will cause an increase in the vibration in the cold state, and it is necessary to control the vibration in the cold state at an acceptable level (the cold state vibration value is less than or equal to 100 μm). If not, perform thermal dynamic balancing. It is difficult to reduce the vibrations in both the cold and hot states to an acceptable level simultaneously.

[0069] Among them, the set threshold value a < the set threshold value b < the set threshold value c < the set threshold value d < the set threshold value e < the set threshold value f.

[0070] The method of thermal dynamic balancing in step S231 is as follows:

[0071] 1. Assume that the cold state vibration values of the bearings at both ends A and B of the generator rotor are A 0l , B 0l respectively, and the hot state vibration values after loading are A 0r , B 0r .

[0072] 2. Add counterweights P a , P b simultaneously at both ends A and B of the generator rotor, with an angular difference of 180° (equal in weight and opposite in angle, that is, P a = P b ), and measure the cold state vibration values at both ends of the generator rotor after adding weights to be A1l , B 1l , the hot-state vibration values after loading are A 1r , B 1r .

[0073] 3. Calculate the influence coefficient a A . Calculate according to formula (1):

[0074]

[0075] 4. Calculate the required counterweight Q at end A A . Calculate according to formula (2):

[0076]

[0077] 5. Calculate the residual vibration A at end A s . Calculate according to formula (3):

[0078] A s = a A Q A + A 0l (9)

[0079] Note: Make the residual vibration A s The cold-state value is less than or equal to 100 μm.

[0080] 6. Calculate the required counterweight Q at end B B . Q B is equal in magnitude and opposite in direction to Q A .

[0081] S3. Judge whether the cold-state fundamental frequency vibration phase is opposite to the hot-state fundamental frequency vibration phase. If so, perform the judgment in step S31. If not, perform the judgment in step S32.

[0082] S31. Judge whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold value e. In this embodiment, the set threshold value e is 120 μm. If the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold value e, use the hot-state dynamic balancing method to solve the abnormal vibration caused by the thermal bending of the generator rotor. When performing hot-state dynamic balancing, use the vibration data in the hot state as the calculation basis, but adding weights will cause an increase in vibration in the cold state, and the vibration in the cold state needs to be controlled within an acceptable level (the cold-state vibration value is less than or equal to 100 μm). If not, taking hot-state dynamic balancing is difficult to reduce the vibrations in both the hot and cold states to an acceptable level at the same time.

[0083] The method of hot-state dynamic balancing in step S31 is as follows:

[0084] 1. Assume that the cold-state vibration values of the bearings at both ends A and B of the generator rotor are A 0l , B 0l, the hot - state vibration values after loading are A respectively 0r and B 0r ;

[0085] 2. Add counterweights P a and P b simultaneously at both ends A and B of the generator rotor, with an angular difference of 180° (the weights are equal in magnitude and opposite in angle, that is, P a = P b ). After adding the weights, the cold - state vibration values at both ends of the generator rotor are A 1l and B 1l respectively, and the hot - state vibration values after loading are A 1r and B 1r ;

[0086] 3. Calculate the influence coefficient a A . Calculate according to formula (1);

[0087]

[0088] 4. Calculate the required counterweight Q A at end A. Calculate according to formula (2);

[0089]

[0090] 5. Calculate the residual vibration A s at end A. Calculate according to formula (3);

[0091] A s = a A Q A + A 0l (12)

[0092] Note: Make the cold - state value of the residual vibration A s less than or equal to 100 μm.

[0093] 6. Calculate the required counterweight Q B at end B. Q B is equal in magnitude and opposite in direction to Q A .

[0094] S32. Determine whether the amplitude of the thermal fundamental frequency vibration is less than or equal to the set threshold f. Among them, the set threshold a < the set threshold e < the set threshold f. In this embodiment, the set threshold f is 150 μm. If the amplitude of the thermal fundamental frequency vibration is less than or equal to the set threshold f, the method of thermal dynamic balancing is used to solve the abnormal vibration caused by the thermal bending of the generator rotor. When performing thermal dynamic balancing, the vibration data in the thermal state is used as the calculation basis. At the same time, the influence of adding weights on the vibration in the cold state should be considered. The vibration in the cold state can be balanced to the reverse of the original vibration, and the vibration value is less than or equal to 50 μm. If not, it is difficult to reduce the vibrations in both the cold and thermal states to an acceptable level by taking thermal dynamic balancing.

[0095] The method of thermal dynamic balancing in step S32 is as follows:

[0096] 1. Assume that the cold-state vibration values of the shaft bearings at both ends A and B of the generator rotor are A 0l and B 0l respectively, and the thermal-state vibration values after loading are A 0r and B 0r respectively;

[0097] 2. Add weights P a and P b simultaneously at both ends A and B of the generator rotor, with an angular difference of 180° (the weights are equal in magnitude and opposite in angle, that is, P a = P b ). Measure the cold-state vibration values of both ends of the generator rotor after adding weights, which are A 1l and B 1l respectively, and the thermal-state vibration values after loading are A 1r and B 1r respectively;

[0098] 3. Calculate the influence coefficient a A . Calculate according to formula (1):

[0099]

[0100] 4. Calculate the required weight Q A at end A. Calculate according to formula (2):

[0101]

[0102] 5. Calculate the residual vibration A s at end A. Calculate according to formula (3):

[0103] A s = a A Q A + A 0l (15)

[0104] Note: Make the residual vibration As The cold state value is less than or equal to 50μm and is related to A 0l Inverted phase.

[0105] 6. Calculate the required counterweight Q at end B B . Q B and Q A are equal in magnitude and opposite in direction.

[0106] In the present invention, the above vibration values are all the peak-to-peak values of the bearing vibration of the bearing bush.

Claims

1. A thermal dynamic balancing method for a generator rotor based on cold and hot fundamental frequency vibrations, characterized in that, It includes the following steps: S1. Obtain vibration characteristic information; the vibration characteristic information includes cold-state vibration overall frequency, cold-state fundamental frequency vibration amplitude, cold-state fundamental frequency vibration phase, hot-state vibration overall frequency, hot-state fundamental frequency vibration amplitude, and hot-state fundamental frequency vibration phase; S2. Judge whether the cold-state fundamental frequency vibration amplitude is greater than or equal to the set threshold a; If the cold-state fundamental frequency vibration amplitude is greater than or equal to the set threshold a, then perform step S21 to judge whether the cold-state fundamental frequency vibration phase is in phase with the hot-state fundamental frequency vibration phase; if the cold-state fundamental frequency vibration amplitude is less than the set threshold a, then perform step S3; S21. If the cold-state fundamental frequency vibration phase is in phase with the hot-state fundamental frequency vibration phase, then adopt the method of hot-state dynamic balancing to solve the abnormal vibration caused by the thermal bending of the generator rotor; If the cold-state fundamental frequency vibration phase is out of phase with the hot-state fundamental frequency vibration phase, then perform the judgment of step S22; S22. Judge whether the cold-state fundamental frequency vibration amplitude is greater than the set threshold b and less than or equal to the set threshold c. If so, perform the judgment of step S221; if not, perform the judgment of step S23; S221. Judge whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold c. If so, then adopt the method of hot-state dynamic balancing to perform hot-state dynamic balancing on the rotor; S23. Judge whether the cold-state fundamental frequency vibration amplitude is greater than the set threshold c. If so, then adopt the method of hot-state dynamic balancing to perform hot-state dynamic balancing on the rotor; if not, perform the judgment of step S231; S231. Judge whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold d. If so, then adopt the method of hot-state dynamic balancing to perform hot-state dynamic balancing on the rotor; S3. Judge whether the cold-state fundamental frequency vibration phase is out of phase with the hot-state fundamental frequency vibration phase; if so, then perform the judgment of step S31; if not, perform the judgment of step S32; S31. Judge whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold e; if the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold e, then adopt the method of hot-state dynamic balancing to solve the abnormal vibration caused by the thermal bending of the generator rotor; S32. Judge whether the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold f; if the hot-state fundamental frequency vibration amplitude is less than or equal to the set threshold f, then adopt the method of hot-state dynamic balancing to solve the abnormal vibration caused by the thermal bending of the generator rotor; Among them, the set threshold a < the set threshold b < the set threshold c < the set threshold d < the set threshold e < the set threshold f.

2. A thermal dynamic balancing method for a generator rotor based on cold and hot fundamental frequency vibrations according to claim 1, characterized in that The method of hot-state dynamic balancing includes the following steps: Suppose the cold-state vibration values of the bearings at both ends A and B of the generator rotor are A 0l and B 0l respectively, and the hot-state vibration values after loading are A 0r and B 0r respectively; Add weights P at both ends A and B of the generator rotor simultaneously a , P b , with an angular difference of 180°. The cold-state vibration values at both ends of the generator rotor after adding weights are measured as A 1l , B 1l respectively. The hot-state vibration values after loading are A 1r , B 1r respectively; Calculate the influence coefficient a A : Calculate the counterweight Q required at end A A : Calculate the counterweight Q required for the B end B .

3. A thermal dynamic balancing method for a generator rotor based on cold and hot state fundamental frequency vibration according to claim 2, characterized in that The counterweight Q required at the B end B and the counterweight Q required at the A end A are equal in magnitude and opposite in direction.

Images