Water turbine thrust bearing oil groove oil level fault detection method

Abstract

The invention discloses a water turbine thrust bearing oil groove oil level fault detection method. The method comprises the following steps that S1, oil level data of a water turbine thrust bearing oil groove are obtained in real time; s2, the change rate of the oil level is obtained; s3, the change acceleration of the oil level is obtained; s4, according to the change rate of the oil level and the change acceleration of the oil level, giving an alarm according to a preset early warning rule; wherein the early warning rule comprises change rate alarm and change acceleration alarm. By introducing the change rate and the change acceleration of the oil level, a more accurate oil level change monitoring mechanism is realized. The change rate reflects the speed of the oil level change, the acceleration reflects the acceleration degree of the oil level change, and changes caused by normal working conditions and external factors and actual fault events can be effectively distinguished through combined monitoring of the change rate and the acceleration.

Description

Technical Field

[0001] The invention relates to the technical field of water turbine thrust bearing oil tank oil level fault detection, in particular to a water turbine thrust bearing oil tank oil level fault detection method. Background Art

[0002] As a large hydroelectric device, the thrust bearings of hydraulic turbines are subject to significant mechanical stress and thermal loads during long-term operation. Therefore, monitoring the oil level in the thrust bearing oil sump is crucial. The oil level in the sump is directly related to the lubrication and heat dissipation performance of the bearings, and ensuring their proper operation is crucial for the safety and efficiency of the turbine. The oil sump houses water-cooled heat exchange pipes, and traditional oil level monitoring methods primarily rely on detecting oil leaks or water ingress by measuring the oil level in the sump.

[0003] However, oil level fluctuations are often affected by multiple factors, such as changes in operating conditions, refueling operations, and ambient temperature fluctuations, which can cause short-term fluctuations in the oil level. Therefore, relying solely on oil level height to determine abnormal conditions can easily lead to false alarms and fail to accurately reflect the actual state of the oil tank. These false alarms not only complicate system maintenance but can also prevent potential faults from being identified and addressed in a timely manner.

[0004] To solve this problem, there is an urgent need to design a more accurate and reasonable oil level monitoring method that can effectively distinguish fluctuations under normal operating conditions from real abnormal conditions, such as oil leakage or water ingress, and reduce the interference of external factors on the monitoring system. Summary of the Invention

[0005] In order to solve the current technical problems, the main purpose of the present invention is to provide a method for detecting oil level faults in the thrust bearing oil tank of a turbine. By introducing the oil level change rate and change acceleration, a more accurate oil level change monitoring mechanism is implemented, which can effectively distinguish between changes caused by normal operating conditions and external factors and actual fault events.

[0006] To overcome the problems existing in the prior art, the present invention adopts a technical solution: a method for detecting an oil level fault in a hydraulic turbine thrust bearing oil tank, comprising the following steps: S1. Obtain oil level data of the turbine thrust bearing oil tank in real time; S2. Obtain the rate of change of the oil level; S3, obtaining the acceleration of the oil level change; S4. Based on the oil level change rate and the oil level change acceleration, an alarm is issued according to a preset early warning rule; wherein the early warning rule includes a change rate alarm and a change acceleration alarm.

[0007] In S2, the rate of change of the oil level is expressed by taking the first derivative of the function of oil level change with time, as shown in the following formula: ; Where: is the function of oil level changing with time; Indicates the rate of change of the oil level, i.e. the speed of the oil level; Indicates the time corresponding to the oil level.

[0008] In S3, the acceleration of the oil level change is expressed by taking the first derivative of the rate of change, as shown in the following formula: ; Where: Indicates the acceleration of oil level change, that is, the speed of change of oil level change rate; is the function of oil level changing with time; Indicates the time corresponding to the oil level.

[0009] In S4, when the absolute value of the oil level change rate continues to exceed the preset threshold, it indicates that the liquid in the oil tank is changing. When the absolute value of the change rate exceeds this threshold and continues for a certain period of time, the system triggers a change rate alarm.

[0010] The trigger time of the rate of change alarm is proportional to the duration of the rate of change exceeding the limit, and the accumulated time is inversely proportional to the degree of threshold exceeding the limit. That is, the longer the exceeding time or the greater the exceeding amplitude, the higher the alarm level.

[0011] When the rate of change exceeds the limit, if the oil level continues to drop or rise without any operation, it is determined that an oil or water leakage fault has occurred.

[0012] In S4, when the absolute value of the acceleration of the oil level change exceeds the threshold, it indicates that the liquid in the oil tank changes more drastically, indicating that the rate of change of the oil level has changed significantly, which means that an unexpected event has occurred.

[0013] When the acceleration exceeds the limit, the cumulative time for triggering the alarm is inversely proportional to the degree of exceeding the threshold, and the greater the exceeding range, the higher the alarm level.

[0014] When the rate of change and acceleration of change exceed the limit at the same time, the alarm level is determined comprehensively based on the degree of each threshold being exceeded. During the alarm process, the accuracy of the alarm is improved through the cumulative error mechanism. When the rate of change or acceleration exceeds the set threshold, the system begins to accumulate the excess error. If the error reaches a certain level and continues for more than the set time, the alarm is triggered.

[0015] The present invention has the following beneficial effects: 1. Monitoring mechanism based on oil level change rate and acceleration: Traditional oil level monitoring methods usually rely on the absolute height change of the oil level to determine whether oil leakage or water ingress has occurred. However, this method cannot effectively distinguish between short-term fluctuations caused by external factors such as refueling and environmental changes and persistent abnormalities caused by oil leakage or water ingress. By introducing the oil level change rate v(t) and changing acceleration a(t) , the present invention realizes a more accurate oil level change monitoring mechanism. Change rate v(t) Reflects the speed of oil level change, while acceleration a(t) It reflects the acceleration of oil level changes. The joint monitoring of the two can effectively distinguish changes caused by normal operating conditions and external factors from actual fault events.

[0016] 2. Multi-threshold joint alarm mechanism based on change rate and acceleration: The present invention innovatively proposes a multi-threshold joint alarm mechanism based on change rate and acceleration. In traditional monitoring methods, only relying on a single oil level change or change rate for alarming is prone to false alarms. By setting reasonable thresholds and combining the change patterns of the change rate and acceleration, the present invention can more sensitively and accurately identify oil leaks and water ingress. Especially in the process of changes caused by oil leakage or water ingress, the change rate and acceleration will show different change patterns. Through multi-threshold processing, the system can achieve more accurate alarm judgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Flowchart of the method of the present invention. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the "present embodiment" or "embodiment" referred to herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention.

[0022] Furthermore, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, when describing the embodiments of the present invention, cross-sectional views illustrating device structures may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0023] Example 1: See also Figure 1 This embodiment provides a method for detecting an oil level fault in a hydraulic turbine thrust bearing tank, comprising the following steps: S1. Obtain oil level data from the turbine thrust bearing oil tank in real time. Install a high-precision level sensor, such as a static pressure level sensor or a capacitive level sensor, at an appropriate location in the turbine thrust bearing oil tank. The sensor should be able to measure the oil level in real time and convert the measurement signal into an electrical or digital signal. S2. Obtain the rate of change of the oil level; S3, obtaining the acceleration of the oil level change; S4. Based on the oil level change rate and the oil level change acceleration, an alarm is issued according to a preset early warning rule; wherein the early warning rule includes a change rate alarm and a change acceleration alarm.

[0024] By introducing both the rate of change and acceleration of the oil level, a more precise oil level monitoring mechanism is achieved. The rate of change reflects the speed of the oil level change, while the acceleration reflects the acceleration of the oil level change. Combined monitoring of the two can effectively distinguish changes caused by normal operating conditions and external factors from actual fault events.

[0025] The rate of change reflects continuous trend changes and is used to determine whether there are chronic problems such as leakage and backflow.

[0026] Acceleration reflects the intensity of sudden changes and is used to determine whether there are sudden events such as rupture and impact.

[0027] In S2, the rate of change of the oil level is expressed by taking the first derivative of the function of oil level change with time, as shown in the following formula: ; Where: is the function of oil level changing with time; Indicates the rate of change of the oil level, i.e. the speed of the oil level; Indicates the time corresponding to the oil level.

[0028] The rate of change is a key indicator for monitoring changes in the oil level in the oil tank. In actual work, changes in oil level are usually affected by external factors such as refueling, changes in operating conditions, temperature fluctuations, etc., and these changes are often short-term and recoverable. If the rate of change of the oil level is only short-term and returns to normal within a certain period of time, there is usually no need to alarm. For example, refueling operations are usually short-term and performed in a shutdown state, which will not cause continuous changes in the oil level. Changes in operating conditions may also cause short-term fluctuations in the oil level. By monitoring the rate of change of the oil level, it can help the system distinguish these normal short-term fluctuations from real fault events such as oil leakage or water ingress. Under normal circumstances, the oil level in the oil tank should remain relatively stable, but under external disturbances, the rate of change v(t) There will be small fluctuations, and no alarm will be triggered if the alarm threshold is not reached.

[0029] In S3, the acceleration of the oil level change is expressed by taking the first derivative of the rate of change, as shown in the following formula: ; Where: Indicates the acceleration of oil level change, that is, the speed of change of oil level change rate; is the function of oil level changing with time; Indicates the time corresponding to the oil level.

[0030] acceleration Used to monitor the severity of oil level changes. If the oil level changes rapidly in a short period of time, such as oil level fluctuations caused by oil leakage or water ingress, the rate of change will increase rapidly, causing a significant change in acceleration. Therefore, oil level acceleration is a key indicator for detecting whether oil leakage or water ingress has occurred. For example, in the case of an oil leak or water ingress, the rate of liquid loss or inflow usually gradually increases, resulting in not only an increase in the rate of oil level change, but also a significant increase in the acceleration of the change. Changes in acceleration can serve as a sensitive response to faults such as an enlarged oil leak or an accelerated water ingress rate. When the acceleration of the oil level change exceeds the set threshold, the system will immediately identify it as an abnormality and trigger an alarm.

[0031] In S4, when the absolute value of the oil level change rate continues to exceed the preset threshold, it indicates that the liquid in the oil tank is changing. When the absolute value of the change rate exceeds this threshold and continues for a certain period of time, the system triggers a change rate alarm.

[0032] The trigger time of the rate of change alarm is proportional to the duration of the rate of change exceeding the limit, and the accumulated time is inversely proportional to the degree of threshold exceeding the limit. That is, the longer the exceeding time or the greater the exceeding amplitude, the higher the alarm level.

[0033] The cumulative time required to trigger a rate-of-change alarm is inversely proportional to the extent of the threshold violation. This means that the greater the violation, the shorter the cumulative time required to trigger the alarm. Different alarm levels are assigned based on the magnitude and duration of the violation. For example, a 2x violation will trigger a higher level than a 1x violation.

[0034] When the rate of change exceeds the limit, if the oil level continues to drop or rise without any operation, it is determined that an oil or water leakage fault has occurred.

[0035] In S4, when the absolute value of the acceleration of the oil level change exceeds the threshold, it indicates that the liquid in the oil tank changes more drastically, indicating that the rate of change of the oil level has changed significantly, which means that an unexpected event has occurred.

[0036] When the acceleration exceeds the limit, the cumulative time for triggering the alarm is inversely proportional to the degree of exceeding the threshold, and the greater the exceeding degree, the higher the alarm level.

[0037] When the rate of change and acceleration of change exceed the limit at the same time, the alarm level is determined comprehensively based on the degree of each threshold being exceeded. During the alarm process, the accuracy of the alarm is improved through the cumulative error mechanism. When the rate of change or acceleration exceeds the set threshold, the system begins to accumulate the excess error. If the error reaches a certain level and continues for more than the set time, the alarm is triggered.

[0038] Specifically, based on the above-defined rate of change and acceleration, design reasonable alarm rules: Change rate alarm: When the oil level changes at a rate v(t) When the absolute value of the rate of change continues to exceed the preset threshold, it indicates that the liquid in the oil tank is changing. Under normal stable operation and no faults, the oil level in the oil tank should remain basically unchanged, and any abnormal fluctuations may indicate potential problems. Since the oil level in the oil tank will be affected by slight fluctuations in actual operation, it is necessary to set a reasonable threshold to filter out these small fluctuations. When the absolute value of the rate of change exceeds this threshold and lasts for a certain period of time, the system triggers an alarm. Specifically, the trigger time of the alarm is proportional to the duration of the excessive rate of change, and the accumulated time is inversely proportional to the degree of the threshold exceeding the limit, that is, the longer the exceeding time or the greater the exceeding amplitude, the higher the alarm level.

[0039] During actual monitoring, the system collects oil level data once per second and calculates the average oil level change rate per minute through numerical differentiation. If the absolute value of the oil level change rate continuously exceeds a set threshold, such as 0.5 mm / min, for more than 5 minutes, a Level 1 alarm is triggered. If the oil level change rate further increases to above 1 mm / min and persists for more than 3 minutes, a Level 2 alarm is triggered. A Level 1 alarm reminds personnel to closely monitor and check for abnormal oil level fluctuations, such as changes in operating conditions or operational reasons. A Level 2 alarm requires immediate action and equipment inspection.

[0040] Change acceleration alarm: Similar to the change rate, the change acceleration of the oil level a(t) A threshold is also required. When the absolute value of the acceleration exceeds this threshold, it indicates that the fluid in the oil tank is changing more dramatically, indicating a significant change in the rate of change of the oil level, particularly in the event of an oil leak or water ingress. Similar to the alarm rules for rate of change, when the acceleration exceeds the limit, the alarm trigger time is inversely proportional to the duration of the limit violation, and the greater the limit violation, the higher the alarm level.

[0041] The system calculates the oil level rate of change once per second and further calculates the change in that rate, known as the oil level acceleration. When the absolute value of the oil level acceleration exceeds a preset threshold, such as 0.2 mm / min², an alarm is immediately triggered. This typically occurs during severe abnormalities such as rapid oil leaks or water ingress, prompting personnel to urgently check the oil tank to prevent equipment damage.

[0042] Multi-threshold Joint Processing: To improve alarm accuracy and avoid false alarms, a multi-threshold joint processing approach is employed. When both the rate of change and acceleration exceed their limits simultaneously, the system weights each threshold according to its severity and comprehensively determines the alarm level. Specifically, if the rate of change and acceleration exceed different thresholds, and the duration of the violations meets preset requirements, an alarm is triggered. The intensity of the alarm is proportional to the magnitude and duration of the rate of change and acceleration violations.

[0043] To improve alarm accuracy, the system simultaneously monitors the oil level rate of change and acceleration. The rate of change threshold is set at 0.5 mm / min and the acceleration threshold at 0.2 mm / min². When both exceed the thresholds, the system immediately triggers a high-level alarm. The alarm level is determined by the weighted degree of the two indicators exceeding the limit. For example, if the rate of change exceeds the threshold by 50% and the acceleration exceeds the threshold by 30%, the alarm level is raised to Level 2. If the limits exceed 80% and 50%, respectively, the alarm level is upgraded to Level 3, requiring immediate shutdown and inspection.

[0044] Error accumulation mechanism: During the alarm process, the system uses an error accumulation mechanism to improve alarm accuracy. When the rate of change or acceleration exceeds a set threshold, the system begins to accumulate the excess error. If the error reaches a certain level and persists for a set time, an alarm is triggered. This mechanism helps prevent false alarms caused by brief, minor fluctuations while accurately identifying continuously changing fault conditions.

[0045] When the oil level rate of change or acceleration exceeds the specified limit repeatedly, but each occurrence is short-lived and insufficient to trigger an alarm individually, the system accumulates the errors from these brief periods. When the accumulated error exceeds a set threshold, such as 2 mm or 0.5 mm / min², an alarm is triggered. This mechanism prevents short-term fluctuations from triggering frequent false alarms while also identifying persistent and intermittent abnormalities, alerting personnel for further investigation.

[0046] To ensure monitoring accuracy, oil level data needs to be preprocessed, such as removing noise and outliers. Smoothing the collected raw oil level data can avoid misjudgments due to transient changes, further improving the robustness of the monitoring system.

Claims

1. A method for detecting oil level fault in a hydraulic turbine thrust bearing tank, characterized in that: The following steps are involved: S1. Obtain oil level data of the turbine thrust bearing oil tank in real time; S2. Obtain the rate of change of the oil level; S3, obtaining the acceleration of the oil level change; S4. Based on the oil level change rate and the oil level change acceleration, an alarm is issued according to a preset early warning rule; wherein the early warning rule includes a change rate alarm and a change acceleration alarm.

2. The method for detecting oil level fault in a hydraulic turbine thrust bearing tank according to claim 1, wherein: In S2, the rate of change of the oil level is expressed by taking the first derivative of the function of oil level change with time, as shown in the following formula: ； Where: is the function of oil level changing with time; Indicates the rate of change of the oil level, i.e. the speed of the oil level; Indicates the time corresponding to the oil level.

3. The method for detecting oil level fault in a hydraulic turbine thrust bearing oil tank according to claim 1, wherein: In S3, the acceleration of the oil level change is expressed by taking the first derivative of the rate of change, as shown in the following formula: ； Where: Indicates the acceleration of oil level change, that is, the speed of change of oil level change rate; is the function of oil level changing with time; Indicates the time corresponding to the oil level.

4. The method for detecting oil level fault in a hydraulic turbine thrust bearing oil tank according to claim 1, wherein: In S4, when the absolute value of the oil level change rate continues to exceed the preset threshold, it indicates that the liquid in the oil tank is changing. When the absolute value of the change rate exceeds this threshold and continues for a certain period of time, the system triggers a change rate alarm.

5. The method for detecting oil level fault in a hydraulic turbine thrust bearing oil tank according to claim 4, wherein: The trigger time of the rate of change alarm is proportional to the duration of the rate of change exceeding the limit, and the accumulated time is inversely proportional to the degree of threshold exceeding the limit. That is, the longer the exceeding time or the greater the exceeding amplitude, the higher the alarm level.

6. The method for detecting oil level fault in a hydraulic turbine thrust bearing tank according to claim 4, wherein: When the rate of change exceeds the limit, if the oil level continues to drop or rise without any operation, it is determined that an oil or water leakage fault has occurred.

7. The method for detecting oil level fault in a hydraulic turbine thrust bearing oil tank according to claim 1, wherein: In S4, when the absolute value of the acceleration of the oil level change exceeds the threshold, it indicates that the liquid in the oil tank changes more drastically, indicating that the rate of change of the oil level has changed significantly, which means that an unexpected event has occurred.

8. The method for detecting oil level fault in a hydraulic turbine thrust bearing tank according to claim 7, wherein: When the acceleration exceeds the limit, the cumulative time for triggering the alarm is inversely proportional to the degree of exceeding the threshold, and the greater the exceeding range, the higher the alarm level.

9. The method for detecting oil level fault in a hydraulic turbine thrust bearing tank according to claim 1, wherein: When the rate of change and acceleration of change exceed the limit at the same time, the alarm level is determined comprehensively based on the degree of each threshold being exceeded.

10. The method for detecting oil level fault in a hydraulic turbine thrust bearing oil tank according to claim 1, wherein: During the alarm process, the accuracy of the alarm is improved through the cumulative error mechanism. When the rate of change or acceleration exceeds the set threshold, the system begins to accumulate the excess error. If the error reaches a certain level and continues for more than the set time, the alarm is triggered.

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