CN110702394B - Vibration change characteristic-based vibration fault diagnosis method for steam turbine generator unit - Google Patents
Vibration change characteristic-based vibration fault diagnosis method for steam turbine generator unit Download PDFInfo
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- CN110702394B CN110702394B CN201910995343.9A CN201910995343A CN110702394B CN 110702394 B CN110702394 B CN 110702394B CN 201910995343 A CN201910995343 A CN 201910995343A CN 110702394 B CN110702394 B CN 110702394B
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Abstract
The invention discloses a vibration fault diagnosis method of a steam turbine generator unit based on vibration change characteristics, which is used for identifying the vibration fault of a steam turbine generator unit shafting by extracting and analyzing vibration change characteristic indexes such as vibration fluctuation, vibration jump, vibration repeatability and the like.
Description
Technical Field
The invention belongs to the field of power machinery engineering, and relates to a vibration fault diagnosis method for a steam turbine generator unit based on vibration change characteristics.
Background
Vibration is the most common fault threatening the safe and stable operation of the turbo generator set, but the mechanism of the vibration fault is very complex and the related range is wide, so the vibration is always a difficult problem which troubles the power production.
At present, the vibration fault diagnosis work of the steam turbine generator unit is mainly completed by experts with abundant experience, namely: after finding out the vibration alarm, the professional personnel of the power plant invites a vibration specialist to go to the site for vibration test and fault diagnosis, and then performs vibration treatment. The process consumes higher economic cost, has long period, cannot ensure the real-time performance and high efficiency of vibration fault diagnosis, and part of units may not be ready for expert tests, and trip is caused by vibration protection action, so that great economic loss and severe social influence are caused, and a diagnosis method is required to be developed, wherein the diagnosis method can be used for carrying out vibration fault of the steam turbine generator unit based on vibration change characteristics.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a vibration fault diagnosis method of a steam turbine generator unit based on vibration change characteristics, which can realize the vibration fault diagnosis of the steam turbine generator unit based on the vibration change characteristics and has excellent real-time performance and high efficiency.
In order to achieve the purpose, the vibration fault diagnosis method of the steam turbine generator unit based on the vibration change characteristics comprises the following steps:
1) obtaining vibration information of a shafting of the steam turbine generator unit, and when the vibration amplitude of the shafting of the steam turbine generator unit exceeds a preset vibration alarm value or the vibration fluctuation amplitude of the shafting of the steam turbine generator unit exceeds a preset amplitude, indicating that the vibration of the shafting of the steam turbine generator unit is abnormal, and turning to the step 2);
2) when the vibration fluctuation amplitude of the shaft system of the steam turbine generator unit is less than or equal to 20%, the vibration of the shaft system of the steam turbine generator unit is not fluctuated, and then the problem that a rotor in the shaft system of the steam turbine generator unit is unbalanced is solved, otherwise, the step 3 is carried out;
3) detecting the vibration trend of all measuring points at the same bearing in a shaft system of the steam turbine generator unit or the vibration trend of all measuring points on the same rotor, and when only one measuring point has vibration fluctuation or the shaft vibration and bearing vibration trends are inconsistent, indicating that the vibration fluctuation belongs to error signals caused by measurement deviation; otherwise, turning to the step 4);
4) judging whether the vibration of the shafting of the steam turbine generator unit jumps or not, namely when the time spent on the vibration of the shafting of the steam turbine generator unit to fluctuate from one state to another state is less than 2min, indicating that the vibration of the shafting of the steam turbine generator unit jumps, and turning to the step 5); otherwise, indicating that the vibration of the shafting of the steam turbine generator unit is in slow-change type fluctuation, and turning to the step 7);
5) determining whether the vibration of the shafting of the steam turbine generator unit continuously jumps or not, and turning to the step 6 when the vibration of the shafting of the steam turbine generator unit continuously jumps; when the vibration of the shaft system of the steam turbine generator unit only generates one jump and the steam turbine generator unit still stably operates in a new vibration state after the jump and the working condition is randomly adjusted, indicating that the rotor component in the shaft system of the steam turbine generator unit has displacement, fracture or falling fault, otherwise, turning to the step 6);
6) when the vibration of the shafting of the steam turbine generator unit is continuously jumping, the self-excited vibration of the shafting of the steam turbine generator unit is indicated; when the vibration of the shafting of the steam turbine generator unit only appears once jumping and the working condition is randomly adjusted after jumping, the steam turbine generator unit cannot continuously and stably operate in a new vibration state, and the vibration of the shafting of the steam turbine generator unit can be recovered through the variable working condition, so that the self-excited vibration of the shafting of the steam turbine generator unit is indicated;
7) determining whether the vibration of the shaft system of the steam turbine generator unit has repeatability, and if the vibration of the shaft system of the steam turbine generator unit is uneven and has repeatability, indicating that the steam turbine generator unit has dynamic and static rubbing faults; when the vibration of the shafting of the steam turbine generator unit has repeatability, turning to the step 8);
8) determining whether the shaft system of the steam turbine generator unit gradually climbs within the range exceeding the preset time, and when the shaft system of the steam turbine generator unit gradually climbs within the range exceeding the preset time, indicating that the rotor of the shaft system of the steam turbine generator unit possibly has cracks; when the shaft system of the turbonator set does not climb gradually within the range exceeding the preset time, the step 9) is carried out;
9) determining whether the vibration of the shafting of the steam turbine generator unit is in a linear relation with the active load, and when the vibration of the shafting of the steam turbine generator unit is in a linear relation with the active load, indicating that the paired wheel in the shafting of the steam turbine generator unit is loosened; when the vibration of the shafting of the steam turbine generator unit is not in a linear relation with the active load, turning to the step 10);
10) the rotor of the turbo-generator set shaft system may have thermal bending.
The specific operation of the step 1) is as follows:
and (3) obtaining vibration information of the steam turbine generator unit shafting, and when the relative shaft vibration of the steam turbine generator unit shafting exceeds 120-165 mu m, the bearing vibration exceeds 50-68 mu m, the relative shaft vibration variation amplitude exceeds 30 mu m or the bearing vibration variation amplitude exceeds 15 mu m, indicating that the steam turbine generator unit shafting has vibration fault, and going to step 2).
In the step 2), the vibration fluctuation amplitude A of the shafting of the steam turbine generator unit is less than or equal to 20 percent, namely
(Amax-Amin)/AAverage×100％≤20％
Indicating that the rotor has unbalance, wherein the vibration abnormality excited by the unbalance is derived from unbalance of rotor mass, permanent bending of the rotor, non-moderate rotor, loose connection of rotor parts or structural resonance, and carrying out field balance test, wheel overhaul adjustment or dynamic stiffness optimization when waiting for next shutdown of the turbonator so as to eliminate the unbalance of the rotor.
In the step 3), when only one measuring point has vibration fluctuation or the shaft vibration and the tile vibration trends are inconsistent, it is indicated that the vibration fluctuation belongs to a false signal caused by measurement deviation, and a worker needs to remove protection logic from the measuring point to wait for the worker to overhaul and replace the measuring point.
The specific operation of the step 4) is as follows:
41) recording the moment t when the shafting vibration of the steam turbine generator unit starts1；
42) Recording the moment t when the vibration fluctuation amplitude of the shafting of the steam turbine generator unit exceeds 20 percent of the average vibration amplitude2；
43) When t is2-t1<When 2min is reached, the vibration of the shafting of the steam turbine generator unit is shown to jump, and then the step 5) is carried out; otherwise, indicating that the vibration of the shafting of the steam turbine generator unit is in the slowly-varying type fluctuation, and turning to the step 7).
Step 6), when the shafting of the steam turbine generator unit generates self-excited vibration, the self-excited vibration comprises steam flow excitation and oil film whirl, when the vibration of the steam turbine generator unit jumps and has threshold load and the vibration happens on the high and medium pressure rotor, the self-excited vibration is indicated as steam flow excitation, otherwise, the self-excited vibration is indicated as oil film whirl;
when the self-excited vibration is steam flow excitation, an operator needs to reduce the load of the steam turbine generator unit and adjust the opening of the regulating valve so as to reduce the steam flow excitation force; when the self-excited vibration is oil film whirl, the operator needs to increase the temperature and pressure of the inlet oil of the lubricating oil, adjust the vacuum of the exhaust cylinder and start the top shaft oil pump so as to improve the bearing stability.
The specific operation of the step 7) is as follows:
comparing the vibration difference of the shafting of the turbo generator unit at different moments in the last two days under the same operation condition, when the vibration difference of the shafting of the turbo generator unit exceeds 50% of the average vibration amplitude and the vibration fluctuation has contingency, indicating that the turbo generator unit has dynamic and static rubbing faults, when the vibration fluctuation occurs at the high and medium pressure sides, the vibration fluctuation periods are consistent each time, and the fluctuation period is less than 2h, indicating that the oil gear has carbon deposition friction, and at the moment, an exhaust fan needs to be added to reduce the temperature of the oil gear or reduce the negative pressure of a bearing box, reduce the dust amount adsorbed on the oil gear and slow down the vibration intensity of the oil gear carbonization friction; when the vibration fluctuation occurs in the heating or cooling process of the cylinder or the intensity of the vibration fluctuation is associated with the temperature of the cylinder, the fact that the cylinder has dynamic and static friction caused by uneven expansion is indicated, at the moment, the main steam parameters need to be reduced, the steam flow entering the cylinder is increased, and all parts of the cylinder are fully and uniformly heated;
when carbon deposit friction does not exist in the oil gear and dynamic and static friction does not exist in the cylinder due to uneven expansion, vibration fluctuation is classified as dynamic and static friction caused by too small adjustment of an installation gap, uneven gap and deformation of dynamic and static parts, and at the moment, under the premise of ensuring the safety of equipment, shaft vibration is maintained at 120-165 mu m or tile vibration is maintained at 50-70 mu m, the relative stability of load and shaft seal steam supply parameters is controlled, and the dynamic and static gaps are gradually and uniformly ground to eliminate the dynamic and static friction.
The specific operation of step 8) is:
the method comprises the steps that a TSI system is used for obtaining vibration data of a steam turbine generator unit shafting continuously running for more than one month recently, trend analysis is carried out, when the vibration of the steam turbine generator unit shafting gradually climbs, it is indicated that cracks may exist in a rotor, wherein when cracks may exist in a high-medium pressure rotor, the temperature of main steam is raised, the pressure of the main steam is reduced, and the trend of vibration development is slowed down; when the low-pressure rotor or the generator rotor possibly has cracks, the operation load of the steam turbine generator unit is reduced, and the trend of vibration development is relieved.
And 9), maintaining the main steam parameters, the exciting current, the reactive power, the generator cooling medium temperature, the lubricating oil temperature and the sealing oil temperature relatively stable on site, improving the active load, and when the vibration increases along with the increase of the active load, and the vibration changes along with the change of the active load immediately without time lag, indicating that the shafting vibration of the steam turbine generator unit has a linear relation with the active load and possibly loosening the pair wheel, simulating the shafting vibration level by reducing the load at the moment, and checking and processing the shafting vibration level when the next machine is stopped.
The specific operation of the step 10) is
101) When the vibration is increased along with the rise of the temperature of the rotor and the vibration is fluctuated after a certain time lag along with the change of the temperature of the rotor, the thermal bending of the rotor is further verified;
102) for the thermal bending of a steam turbine rotor, the temperature of main steam is reduced to operate, and the vibration is controlled to be at the level of safe operation;
103) for the thermal bending of the generator rotor, determining whether the vibration is related to the temperature of a generator cooling medium, and when the vibration is reduced along with the increase of the temperature of the cooling medium, indicating that the generator cooling system is possibly blocked, and at the moment, operating personnel should increase the temperature of the cooling medium to operate so as to control the vibration to be at a safe operation level as much as possible;
when the thermal bending vibration of the generator rotor is irrelevant to the temperature of the cooling medium, the exciting current or the reactive operation is reduced, so that the temperature of the generator rotor is reduced, the degree of thermal bending of the rotor is relieved, and the vibration intensity of the rotor is reduced.
The invention has the following beneficial effects:
the vibration change characteristic indexes of the steam turbine generator unit based on the vibration change characteristics are extracted and analyzed during specific operation to identify the vibration faults of the steam turbine generator unit shafting, so that a basis is provided for a first-line operation and maintenance personnel to timely and accurately take corresponding measures, and the method is excellent in real-time performance and high efficiency. Meanwhile, TSI system data randomly allocated by the steam turbine generator unit can be directly adopted, additional instrument equipment is not needed, the method is convenient to implement on site and reliable in result, various vibration faults can be successfully identified for many times in practice, and huge economic and social benefits are created for power plants.
Drawings
FIG. 1 is a graph showing the active load of a generator and the vibration at a No. 6 bearing in accordance with an embodiment I;
FIG. 2 is a graph showing the variation trend of the generator vibration in the test of varying exciting current and cooling wind temperature according to the first embodiment;
FIG. 3 is a schematic view of a block cooling water circuit according to the first embodiment;
FIG. 4 is a diagram of a gradual vibration fluctuation trend caused by a carbonization friction fault of a bearing oil bearing;
FIG. 5 is a trend graph of a primary vibration jump caused by a high and medium voltage rotor blade fracture fault;
FIG. 6 is a diagram illustrating a trend of continuous jump of vibration of a high-pressure rotor caused by steam excitation;
FIG. 7 is a diagram showing the trend of single-point vibration fluctuation at the No. 4 bearing during the resonance process of the 4X-axis vibration support;
FIG. 8 is a flow chart of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 8 and table 1, the method for diagnosing a vibration fault of a steam turbine generator unit based on a vibration variation characteristic according to the present invention includes the following steps:
1) obtaining vibration information of a shaft system of the steam turbine generator unit, and when the vibration amplitude of the shaft system of the steam turbine generator unit exceeds a preset vibration alarm value or when vibration fluctuation of the shaft system of the steam turbine generator unit occurs, indicating that the vibration of the shaft system of the steam turbine generator unit is abnormal, and turning to the step 2);
2) when the vibration fluctuation amplitude of the shaft system of the steam turbine generator unit is less than or equal to 20%, the vibration of the shaft system of the steam turbine generator unit is not fluctuated, and then the problem that a rotor in the shaft system of the steam turbine generator unit is unbalanced is solved, otherwise, the step 3 is carried out;
3) detecting the vibration trend of all measuring points at the same bearing in a shaft system of the steam turbine generator unit or the vibration trend of all measuring points on the same rotor, and when only one measuring point has vibration fluctuation or the shaft vibration and bearing vibration trends are inconsistent, indicating that the vibration fluctuation belongs to error signals caused by measurement deviation; otherwise, turning to the step 4);
4) judging whether the vibration of the shafting of the steam turbine generator unit jumps or not, namely when the time spent on the vibration of the shafting of the steam turbine generator unit from one state fluctuation to another state fluctuation is less than 2min, indicating that the vibration of the shafting of the steam turbine generator unit jumps, and turning to the step 5); otherwise, indicating that the vibration of the shafting of the steam turbine generator unit is in slow-change type fluctuation, and turning to the step 7);
5) determining whether the vibration of the shafting of the steam turbine generator unit continuously jumps or not, and turning to the step 6 when the vibration of the shafting of the steam turbine generator unit continuously jumps; when the vibration of the shaft system of the steam turbine generator unit only generates one jump and the steam turbine generator unit still stably operates in a new vibration state after the jump and the working condition is randomly adjusted, indicating that the rotor component in the shaft system of the steam turbine generator unit has displacement, fracture or falling fault, otherwise, turning to the step 6);
6) when the vibration of the shafting of the steam turbine generator unit is continuously jumping, the self-excited vibration of the shafting of the steam turbine generator unit is indicated; when the vibration of the shafting of the steam turbine generator unit only appears once jumping and the working condition is randomly adjusted after jumping, the steam turbine generator unit cannot continuously and stably operate in a new vibration state, and the vibration of the shafting of the steam turbine generator unit can be recovered to the state before jumping through the variable working condition, the self-excited vibration of the shafting of the steam turbine generator unit is indicated;
7) determining whether the vibration of the shaft system of the steam turbine generator unit has repeatability, and if the vibration of the shaft system of the steam turbine generator unit does not have repeatability, indicating that the steam turbine generator unit has dynamic and static rubbing faults; when the vibration of the shafting of the steam turbine generator unit has repeatability, turning to the step 8);
8) determining whether the shaft system of the steam turbine generator unit gradually climbs within the range exceeding the preset time, and when the shaft system of the steam turbine generator unit gradually climbs within the range exceeding the preset time, indicating that the rotor of the shaft system of the steam turbine generator unit possibly has cracks; when the shaft system of the turbonator set does not climb gradually within the range exceeding the preset time, the step 9) is carried out;
9) determining whether the vibration of the shafting of the steam turbine generator unit is in a linear relation with the active load, and when the vibration of the shafting of the steam turbine generator unit is in a linear relation with the active load, indicating that the paired wheel in the shafting of the steam turbine generator unit is loosened; when the vibration of the shafting of the steam turbine generator unit is not in a linear relation with the active load, turning to the step 10);
10) the method comprises the following steps that a rotor of a shaft system of the steam turbine generator unit is possibly thermally bent, whether the shaft system of the steam turbine generator unit is related to the temperature of a cooling medium of a generator is judged, when the vibration of the shaft system of the steam turbine generator unit is related to the temperature of the cooling medium of the generator, the surface generator cooling system is possibly blocked, operators need to improve the temperature of the cooling medium of the generator, and the vibration of the shaft system of the steam turbine generator unit is controlled to be at a safe operation level; when the vibration of the shaft system of the steam turbine generator unit is not related to the temperature of the cooling medium of the generator, the exciting current or the reactive operation of the generator is reduced, the temperature of the rotor of the generator is reduced, the degree of thermal bending of the rotor is relieved, and the vibration intensity of the shaft system of the steam turbine generator unit is further reduced.
The specific operation of the step 1) is as follows:
and (3) obtaining vibration information of the steam turbine generator unit shafting, and when the relative shaft vibration of the steam turbine generator unit shafting exceeds 120-165 mu m, the bearing vibration exceeds 50-68 mu m, the relative shaft vibration variation amplitude exceeds 30 mu m or the bearing vibration variation amplitude exceeds 15 mu m, indicating that the steam turbine generator unit shafting has vibration fault, and going to step 2).
In the step 2), the vibration fluctuation amplitude A of the shafting of the steam turbine generator unit is less than or equal to 20 percent, namely
(Amax-Amin)/AAverage×100％≤20％
Indicating that the rotor has unbalance, wherein the vibration abnormality excited by the unbalance is derived from unbalance of rotor mass, permanent bending of the rotor, non-moderate rotor, loose connection of rotor parts or structural resonance, and carrying out field balance test, wheel overhaul adjustment or dynamic stiffness optimization when waiting for next shutdown of the turbonator so as to eliminate the unbalance of the rotor.
In the step 3), when only one measuring point has vibration fluctuation or the shaft vibration and the tile vibration trends are inconsistent, it is indicated that the vibration fluctuation belongs to a false signal caused by measurement deviation, and a worker needs to remove protection logic from the measuring point to wait for the worker to overhaul and replace the measuring point.
The specific operation of the step 4) is as follows:
41) recording the moment t when the shafting vibration of the steam turbine generator unit starts1；
42) Recording the moment t when the vibration fluctuation amplitude of the shafting of the steam turbine generator unit exceeds 20 percent of the average vibration amplitude2；
43) When t is2-t1<When 2min is reached, the vibration of the shafting of the steam turbine generator unit is shown to jump, and then the step 4) is carried out; otherwise, indicating that the vibration of the shafting of the steam turbine generator unit is in the slowly-varying type fluctuation, and turning to the step 7).
Step 6), when the shafting of the steam turbine generator unit generates self-excited vibration, the self-excited vibration comprises steam flow excitation and oil film whirl, when the vibration of the steam turbine generator unit jumps and has threshold load and the vibration happens on the high and medium pressure rotor, the self-excited vibration is indicated as steam flow excitation, otherwise, the self-excited vibration is indicated as oil film whirl;
when the self-excited vibration is steam flow excitation, an operator needs to reduce the load of the steam turbine generator unit and adjust the opening of the regulating valve so as to reduce the steam flow excitation force; when the self-excited vibration is oil film whirl, the operator needs to increase the temperature and pressure of the inlet oil of the lubricating oil, adjust the vacuum of the exhaust cylinder and start the top shaft oil pump so as to improve the bearing stability.
The specific operation of the step 7) is as follows:
comparing the vibration difference of the shafting of the turbo generator unit at different moments in the last two days under the same operation condition, when the vibration difference of the shafting of the turbo generator unit exceeds 50% of the average vibration amplitude and the vibration fluctuation has contingency, indicating that the turbo generator unit has dynamic and static rubbing faults, when the vibration fluctuation occurs at the high and medium pressure sides, the vibration fluctuation periods are consistent each time, and the fluctuation period is less than 2h, indicating that the oil gear has carbon deposition friction, and at the moment, an exhaust fan needs to be added to reduce the temperature of the oil gear or reduce the negative pressure of a bearing box, reduce the dust amount adsorbed on the oil gear and slow down the vibration intensity of the oil gear carbonization friction; when the vibration fluctuation occurs in the heating or cooling process of the cylinder or the intensity of the vibration fluctuation is associated with the temperature of the cylinder, the fact that the cylinder has dynamic and static friction caused by uneven expansion is indicated, at the moment, the main steam parameters need to be reduced, the steam flow entering the cylinder is increased, and all parts of the cylinder are fully and uniformly heated;
when carbon deposit friction does not exist in the oil gear and dynamic and static friction does not exist in the cylinder due to uneven expansion, the dynamic and static friction is classified as dynamic and static friction caused by undersize adjustment of an installation gap, uneven gap and deformation of dynamic and static parts, at the moment, under the premise of ensuring the safety of equipment, shaft vibration is maintained at 120-165 mu m or tile vibration is maintained at 50-70 mu m, the relative stability of load and shaft seal steam supply parameters is controlled, and the dynamic and static gap is gradually and uniformly ground to eliminate the dynamic and static friction.
The specific operation of step 8) is:
the method comprises the steps that a TSI system is used for obtaining vibration data of a steam turbine generator unit shafting continuously running for more than one month recently, trend analysis is carried out, when the vibration of the steam turbine generator unit shafting gradually climbs, it is indicated that cracks may exist in a rotor, wherein when cracks may exist in a high-medium pressure rotor, the temperature of main steam is raised, the pressure of the main steam is reduced, and the trend of vibration development is slowed down; when the low-pressure rotor or the generator rotor possibly has cracks, the operation load of the steam turbine generator unit is reduced, and the trend of vibration development is relieved.
And 9), maintaining the main steam parameters, the exciting current, the idle work, the temperature of a cooling medium of the generator, the temperature of a lubricating oil and the temperature of a sealing oil relatively stable on site, improving the active load, and when the vibration increases along with the increase of the active load, and the vibration changes along with the change of the active load without time lag, indicating that the shafting vibration of the turbo generator unit and the active load have a linear relation, and also indicating that the pair wheel possibly loosens, simulating the shafting vibration level by reducing the load at the moment, and carrying out inspection processing when the next machine is stopped.
The specific operation of the step 10) is as follows:
101) when the vibration is increased along with the rise of the temperature of the rotor and the vibration fluctuates after a certain time (5 min) lags along with the change of the temperature of the rotor, the thermal bending of the rotor is further verified;
102) for the thermal bending of a steam turbine rotor, the temperature of main steam is reduced to operate, and the vibration is controlled to be at the level of safe operation;
103) for the thermal bending of the generator rotor, determining whether the vibration is related to the temperature of a generator cooling medium, and when the vibration is reduced along with the increase of the temperature of the cooling medium, indicating that the generator cooling system is possibly blocked, and at the moment, operating personnel should increase the temperature of the cooling medium to operate so as to control the vibration to be at a safe operation level as much as possible;
when the thermal bending vibration of the generator rotor is irrelevant to the temperature of the cooling medium, the exciting current or the reactive operation is reduced, so that the temperature of the generator rotor is reduced, the degree of thermal bending of the rotor is relieved, and the vibration intensity of the rotor is reduced.
TABLE 1
Example one
The invention successfully diagnoses various vibration problems in the operation of dozens of steam turbine generator units only in 2019, and the representative performance is shown in Table 2
TABLE 2
Now, taking the blockage fault of the rotor cooling system of the No. 2 generator (300MW) of Shenhua national energy and Rich coal and electricity Limited company as an example, the whole process of the invention for diagnosing the thermal bending fault of the rotor is described in detail to illustrate the effectiveness and the applicability of the invention.
In the No. 2 unit, during the load operation, the generator rotor vibration (No. 5 and No. 6 shaft vibration) has obvious fluctuation, namely: when the active load of the unit is less than 200MW, the vibration is at a good level (<80 μm), and as the load increases, the vibration of the generator slowly climbs until reaching about 130 μm under the rated load condition, and referring to FIG. 1, the vibration alarm value (125 μm) is exceeded.
As can be seen from FIG. 1, the vibration of each point at the No. 6 bearing fluctuates synchronously, which shows that the vibration measurement result is real and reliable.
Shaft vibration No. 6 shows gradual fluctuation (>2min) and increases with the increase of the active load, but the vibration can be recovered after the decrease of the active load, which shows that the vibration has repeatability.
Compared with the moment of active load change, the vibration fluctuation of the No. 6 shaft has obvious time lag (>5min), which indicates that the generator rotor is thermally bent; in fact, as the exciting current increases, the heat generation of the generator rotor increases, and the vibration at bearings No. 5 and No. 6 begins to climb gradually after about 20min, referring to FIG. 2;
in the variable-cold-air-temperature test, the shaft vibrations No. 5 and No. 6 decrease with the increase of the cold air temperature of the generator and vice versa, and referring to FIG. 2, the blockage of the cooling system of the generator is shown.
Therefore, in the running of the unit, the exciting current and the reactive output of the No. 2 generator are reduced as much as possible by the adjustment of the adjacent unit, so that the vibration is basically controlled to be about 100 mu m; in addition, in the later unit maintenance, a water channel of the generator is also found to be blocked by the maintenance cloth, and the early diagnosis conclusion is verified by referring to fig. 3.
Claims (9)
1. A vibration fault diagnosis method of a steam turbine generator unit based on vibration change characteristics is characterized by comprising the following steps:
1) obtaining vibration information of a shafting of the steam turbine generator unit, and when the vibration amplitude of the shafting of the steam turbine generator unit exceeds a preset vibration alarm value or the vibration fluctuation amplitude of the shafting of the steam turbine generator unit exceeds a preset amplitude, indicating that the vibration of the shafting of the steam turbine generator unit is abnormal, and turning to the step 2);
2) when the vibration fluctuation amplitude of the shaft system of the steam turbine generator unit is less than or equal to 20%, the vibration of the shaft system of the steam turbine generator unit is not fluctuated, and then the problem that a rotor in the shaft system of the steam turbine generator unit is unbalanced is solved, otherwise, the step 3 is carried out;
3) detecting the vibration trend of all measuring points at the same bearing in a shaft system of the steam turbine generator unit or the vibration trend of all measuring points on the same rotor, and when only one measuring point has vibration fluctuation or the shaft vibration and bearing vibration trends are inconsistent, indicating that the vibration fluctuation belongs to error signals caused by measurement deviation; otherwise, turning to the step 4);
4) judging whether the vibration of the shafting of the steam turbine generator unit jumps or not, namely when the time spent on the vibration of the shafting of the steam turbine generator unit from one state fluctuation to another state fluctuation is less than 2min, indicating that the vibration of the shafting of the steam turbine generator unit jumps, and turning to the step 5); otherwise, indicating that the vibration of the shafting of the steam turbine generator unit is in slow-change type fluctuation, and turning to the step 7);
5) determining whether the vibration of the shafting of the steam turbine generator unit continuously jumps or not, and turning to the step 6 when the vibration of the shafting of the steam turbine generator unit continuously jumps; when the vibration of the shaft system of the steam turbine generator unit only generates one jump and the steam turbine generator unit still stably operates in a new vibration state after the jump and the working condition is randomly adjusted, indicating that the rotor component in the shaft system of the steam turbine generator unit has displacement, fracture or falling fault, otherwise, turning to the step 6);
6) when the vibration of the shafting of the steam turbine generator unit is continuously jumping, the self-excited vibration of the shafting of the steam turbine generator unit is indicated; when the vibration of the shafting of the steam turbine generator unit only appears once jumping and the working condition is randomly adjusted after jumping, the steam turbine generator unit cannot continuously and stably operate in a new vibration state, and the vibration of the shafting of the steam turbine generator unit can be recovered to the state before jumping through the variable working condition, thus indicating that the shafting of the steam turbine generator unit generates self-excited vibration;
7) determining whether the vibration of the shaft system of the steam turbine generator unit has repeatability, and if the vibration of the shaft system of the steam turbine generator unit does not have repeatability, indicating that the steam turbine generator unit has dynamic and static rubbing faults; when the vibration of the shafting of the steam turbine generator unit has repeatability, turning to the step 8);
8) determining whether the shaft system of the steam turbine generator unit gradually climbs within the range exceeding the preset time, and when the shaft system of the steam turbine generator unit gradually climbs within the range exceeding the preset time, indicating that the rotor of the shaft system of the steam turbine generator unit possibly has cracks; when the shaft system of the turbonator set does not climb gradually within the range exceeding the preset time, the step 9) is carried out;
9) determining whether the vibration of the shafting of the steam turbine generator unit is in a linear relation with the active load, and when the vibration of the shafting of the steam turbine generator unit is in a linear relation with the active load, indicating that the paired wheel in the shafting of the steam turbine generator unit is loosened; when the vibration of the shafting of the steam turbine generator unit is not in a linear relation with the active load, turning to the step 10);
10) the rotor of the turbo-generator set shaft system may have thermal bending.
2. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics as claimed in claim 1, wherein in the step 2), the vibration fluctuation amplitude A of the steam turbine generator unit shafting is less than or equal to 20 percent, namely
(Amax-Amin)/AAverage×100％≤20％
Indicating that the rotor has unbalance, wherein the vibration abnormality excited by the unbalance is derived from unbalance of rotor mass, permanent bending of the rotor, non-moderate rotor, loose connection of rotor parts or structural resonance, and carrying out field balance test, wheel overhaul adjustment or dynamic stiffness optimization when waiting for next shutdown of the turbonator so as to eliminate the unbalance of the rotor.
3. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics as claimed in claim 1, wherein in the step 3), when only one measuring point has vibration fluctuation or the shaft vibration and the bearing vibration have inconsistent trends, it indicates that the vibration fluctuation belongs to a false signal caused by measurement deviation, and the worker needs to remove the protection logic from the measuring point and wait for the worker to repair and replace the measuring point.
4. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics is characterized in that the specific operation of the step 4) is as follows:
41) recording the moment t when the shafting vibration of the steam turbine generator unit starts1；
42) Recording the moment t when the vibration fluctuation amplitude of the shafting of the steam turbine generator unit exceeds 20 percent of the average vibration amplitude2；
43) When t is2-t1<When 2min is reached, the vibration of the shafting of the steam turbine generator unit is shown to jump, and then the step 5) is carried out; otherwise, indicating that the vibration of the shafting of the steam turbine generator unit is in the slowly-varying type fluctuation, and turning to the step 7).
5. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics as claimed in claim 1, wherein in step 6), when the steam turbine generator unit shafting generates self-excited vibration, the self-excited vibration comprises steam flow excitation and oil film whirl, when the vibration of the steam turbine generator unit jumps, a threshold load exists, and the vibration jumps on the high and medium pressure rotor, the self-excited vibration is indicated as steam flow excitation, otherwise, the self-excited vibration is indicated as oil film whirl;
when the self-excited vibration is steam flow excitation, an operator needs to reduce the load of the steam turbine generator unit and adjust the opening of the regulating valve so as to reduce the steam flow excitation force; when the self-excited vibration is oil film whirl, the operator needs to increase the temperature and pressure of the inlet oil of the lubricating oil, adjust the vacuum of the exhaust cylinder and start the top shaft oil pump so as to improve the bearing stability.
6. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics as claimed in claim 1, wherein the specific operation of the step 7) is as follows:
comparing the vibration difference of the shafting of the turbo generator unit at different moments in two last days under the same operation condition, when the vibration difference of the shafting of the turbo generator unit exceeds 50% of the average vibration amplitude and the vibration fluctuation has contingency, indicating that the turbo generator unit has dynamic and static rubbing faults, when the vibration fluctuation occurs at high and medium pressure sides, the vibration fluctuation periods are consistent each time, and the fluctuation period is less than 2h, indicating that the oil gear has carbon deposit friction, and at the moment, increasing an exhaust fan to reduce the temperature of the oil gear or reduce the negative pressure of a bearing box, reduce the dust amount adsorbed on the oil gear and slow down the vibration intensity of the oil gear carbonization friction; when the vibration fluctuation occurs in the heating or cooling process of the cylinder or the intensity of the vibration fluctuation is associated with the temperature of the cylinder, the fact that the cylinder has dynamic and static rubbing caused by uneven expansion is indicated, at the moment, the main steam parameters need to be reduced, the steam flow entering the cylinder is increased, and all parts of the cylinder are fully and uniformly heated;
when carbon deposit friction does not exist in the oil gear and dynamic and static friction caused by uneven expansion does not exist in the cylinder, the vibration fluctuation reason is classified as dynamic and static friction caused by undersize adjustment of an installation gap, uneven gap and deformation of dynamic and static parts, at the moment, under the premise of ensuring the safety of equipment, shaft vibration is maintained at 120-165 mu m or tile vibration is maintained at 50-70 mu m, the relative stability of load and shaft seal steam supply parameters is controlled, and the dynamic and static gaps are gradually and uniformly ground to eliminate the dynamic and static friction.
7. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics as claimed in claim 1, wherein the specific operation of the step 8) is as follows:
acquiring vibration data of the steam turbine generator unit shafting continuous operation for more than one month recently by using a randomly-equipped TSI system, performing trend analysis, and when the vibration of the steam turbine generator unit shafting gradually climbs, indicating that the rotor possibly has cracks, wherein when the high-medium pressure rotor possibly has cracks, the temperature of main steam is increased, the pressure of the main steam is reduced, and the trend of vibration development is slowed down; when the low-pressure rotor or the generator rotor possibly has cracks, the operation load of the steam turbine generator unit is reduced, and the trend of vibration development is relieved.
8. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration variation characteristics as claimed in claim 1, wherein in step 9), the main steam parameters, the excitation current, the reactive power, the temperature of the cooling medium of the generator, the temperature of the lubricating oil and the temperature of the sealing oil are maintained relatively stable on site, the active load is increased, when the vibration increases along with the increase of the active load, and the vibration changes along with the change of the active load without time lag, it is indicated that the linear relation exists between the vibration of the steam turbine generator unit shafting and the active load, and also indicated that the wheel pair may be loosened, at this time, the shafting vibration level is planned by reducing the load, and the shafting vibration level is checked and processed at the next shutdown.
9. The vibration fault diagnosis method for the steam turbine generator unit based on the vibration change characteristics as claimed in claim 1, wherein the specific operation of the step 10) is as follows:
101) when the vibration is increased along with the rise of the temperature of the rotor and the vibration is fluctuated after a certain time lag along with the change of the temperature of the rotor, the thermal bending of the rotor is further verified;
102) for the thermal bending of a steam turbine rotor, the temperature of main steam is reduced to operate, and the vibration is controlled to be at the level of safe operation;
103) for the thermal bending of the generator rotor, determining whether the vibration is related to the temperature of a generator cooling medium, and when the vibration is reduced along with the increase of the temperature of the cooling medium, indicating that the generator cooling system is possibly blocked, and at the moment, operating personnel should increase the temperature of the cooling medium to operate so as to control the vibration to be at a safe operation level as much as possible;
when the thermal bending vibration of the generator rotor is irrelevant to the temperature of the cooling medium, the exciting current or the reactive operation is reduced, so that the temperature of the generator rotor is reduced, the degree of thermal bending of the rotor is relieved, and the vibration intensity of the rotor is reduced.
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| CN112284521B (en) * | 2020-10-27 | 2023-04-07 | 西安西热节能技术有限公司 | Quantification and application method of vibration fault characteristics of steam turbine generator unit |
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