CN1007757B - System and method of diagnostics - Google Patents

Abstract

A diagnostic system in which a central diagnostic center receives probe data regarding the operating status of a plurality of remote devices. Certain detector signals are recorded in each device and transmitted within respective predetermined transmission times. If certain starting limit levels are exceeded, a data link is immediately established with the diagnostic center so that it can transmit the data earlier than its normally determined transmission time for immediate rapid diagnostic analysis of the device. The communication link between the device and the diagnostic center is kept open for a predetermined period of time, so that more data can be sent from the device to the diagnostic center during this period, and analysis results and instructions are returned from the diagnostic center to the device.

Description

This invention relates to a diagnostic system for monitoring a process and, more particularly, to devices often used to diagnose possible malfunctions in a process.

Regardless of whether it is from a safety point of view or an economic point of view, it is necessary to continuously monitor the working status of various processes in order to obtain early indications of possible failures, so that some corrective measures can be taken.

For some processes such as power generation of power generation equipment, in order to obtain online indications of many operating parameters, hundreds of detectors are used in the entire power generation equipment. A diagnostic system can be set on the equipment to respond to the detector output. The system continuously interprets the readings of the detector, and provides an indication of the working status of the equipment to the equipment operator, and at the same time makes recommendations to take safety or economic considerations appropriate action to be taken.

This diagnosis can be accomplished using a digital computer stored with a diagnostic program. In a preferred embodiment, recent developments propose the use of computer programs known as knowledge-rich expert systems. These expert systems are rule-based systems that contain many rules that result from the consultation of one or more diagnostic experts for a particular device. Since more information will be obtained after a period of time, the program can be modified by adding, deleting or modifying some rules if necessary.

Typical commonly used equipment may include hundreds of detectors, and the output signals of these detectors must be scanned periodically and stored. For some detectors, the scan frequency may be expressed in seconds, while for others it may be expressed in minutes. Therefore, using an expert diagnostic system or other diagnostic system that requires a huge amount of storage becomes prohibitively expensive for some devices.

The present invention provides a means by which many such devices can be continuously monitored for abnormal operating conditions at a much lower cost than would normally be required for such an operation.

A diagnostic system for monitoring a process at a first location, the process including a plurality of detectors that generate output signals related to the working state of the process, the diagnostic system includes a first location at the first location data storage means, a first computing device located at said first location, a first transmitter/receiver device located at said first location, said first computing device being capable of periodically scanning the output signal of said detector , and those signals showing a predetermined difference in value and those signals exceeding respective predetermined thresholds compared with the previous scan are stored in the above-mentioned first data storage device, the first transmitter/receiver The computer device is controlled by the above-mentioned first computer device, and also includes a diagnostic center at a second location away from the above-mentioned first location, a second computing device capable of performing diagnostic analysis, a second data storage device, and a second transmitter /receiver means, the second transmitter/receiver means receiving data sent from said first location location under the control of said second computing means, a diagnostic analysis being performed by said second computing means, characterized in that, The first transmitter/receiver unit transmits the contents of said first data storage unit via a data link to said diagnostic center within a prearranged period of time, and whenever a signal exceeds its predetermined threshold , just send the above-mentioned content within a period of time not determined in advance, the above-mentioned second transmitter/receiver device can also be used to send the result information of the above-mentioned analysis back to the first transmitter/receiver device through the above-mentioned data link, The above-mentioned first transmitter/receiver means can also be used to receive the information transmitted therefrom.

Conveniently, the first data storage means is positioned at the first location and there is also a computer means at this position which periodically scans the output signals generated by the detector and compares those with the previous The subscan comparisons, signals exhibiting predetermined differences in value, and those signals exceeding respective predetermined thresholds are stored in the data storage means.

A diagnostic center at a second location remote from the first location includes data storage means and computing means, thereby enabling diagnostic analysis to be performed. The transmitter/receiver unit at the first location is under the control of the computer unit in order to transmit the contents of the first data storage unit to the diagnostic center at a prearranged time, such as every hour. of. The apparatus is practicable so that, between normal transmissions, whenever a signal exceeds its predetermined threshold, it will transmit a signal in the first data storage means for an undetermined period of time. Content.

The diagnostic center includes means for receiving data from the first location so that diagnostic analysis can be performed and the results of the analysis sent back to the first location. In this way, it is possible to simultaneously monitor the many processes.

Now, we illustrate the present invention by way of example with reference to the accompanying drawings. In the attached picture:

Fig. 1 is a block diagram of an embodiment of the present invention;

Figure 2 is a graph depicting the output of a typical process detector;

Figure 3 is a flow chart illustrating the operation of the system at a process location location;

Figure 4 is a flowchart illustrating the operation of the system at the diagnostic center.

Although the diagnosis system in the present invention can be used for multi-process diagnosis, no matter it is the process diagnosis on the static positioning or the process diagnosis on the dynamic positioning, we still only give an example about a set of power generation equipment to illustrate it. Specifically, it will be described based on an example of power generation equipment such as a turbo generator.

FIG. 1 shows a large number of power generating plants designated by numerals 1, 2, . . . n, a typical one of which is illustrated by plant 2. The plant comprises at least one steam turbine 10 which can be used to drive a generator 11 which is fed with field current from an exciter 12 . Typical equipment includes many probes, such as those used to measure temperature at different locations in such devices as steam turbines, generators, and exciters, and to measure pressure, vibration, speed, current, voltage, frequency, humidity, etc. and other detectors.

The equipment at its location includes an input-output circuit 14 and a data acquisition computer that can be used to periodically scan the output signals of all detectors and store certain signals in a data register 18 16. Due to the somewhat limited data storage capacity on the device, only certain signals from these detectors can be stored. According to standard practice, only those detector signals which exceed the predetermined dead zone are stored. That is to say, if a detector signal, the value obtained in one scan, compared with the value stored in the previous scan, its change exceeds a predetermined amount, then the signal of this detector will be stored in the Data storage 18.

According to the invention, the signal of a detector is additionally stored if its signal value exceeds some predetermined positive-going threshold level or negative-going threshold level; The limited signals are stored. Here, detector signal means not only the output signal of a single detector, but also a predetermined combination of some detector output signals, the average value of n detector signals being an example.

A transmitter/receiver unit, represented by communication interface 20, is under the control of computer 16 and periodically transmits the contents of data memory 18 to a remote diagnostic center 30. For example, such a periodic send might be hourly, in which case all data collected since the previous send would be sent. However, if the signal values of one or more detectors exceed their respective threshold levels or rate-of-change limits, then the normal cycle transmission routine will be interrupted so that the data stored in the data store 18 will be transmitted immediately. content so that the diagnostic center can perform immediate rapid analysis when the power generation equipment is in a state of increasing danger.

Transmission of this data may still proceed in the event that no detector's signal value exceeds its predetermined deadband, and no detector's signal value exceeds its predetermined threshold level or rate-of-change limit, to indicate that the system is Works, except that the data is exactly the same as what was sent the previous hour.

Diagnostic center 30 includes a diagnostic center computer 32 and a long term memory 34 of sufficient capacity to store all or most of the data sent from all devices. The computer 32 can be used to perform diagnostic analysis on the received data and, in one embodiment, can be equipped with an expert system type program.

For accessing the computer 32, an operator terminal 36 may be included, and may also include one or more monitors and a keyboard for man-to-machine dialogue controls.

In the diagnostic center, a transmitter/receiver device, represented by a communication interface 33, is provided, under the control of a computer 32, to receive data sent from all devices in their respective cycles, and Data sent from indoubt send. Diagnosis results and instruction information can be sent back to each device through the communication interface, and these results can be displayed on the display of the operation terminal 40 .

In one embodiment, the communication interface may be in the form of a modem, thereby establishing a data link through a conventional telephone line. It is also possible to use other types of data links, such as sending data via satellite from the diagnostic center to the device, or vice versa, which is more specific when the device and the diagnostic center are located on different continents.

The operation of the present invention will be described for a single probe in the form of a temperature probe. Use Figure 2 to illustrate its temperature The relationship between temperature and time, where the axis of ordinate represents temperature and the axis of abscissa represents time.

Assume that this particular detector is a thermocouple with an upper temperature threshold of 60°C and a lower temperature threshold of 30°C, where the temperature is expressed in degrees Celsius. The detector has a temperature change rate limit of 20°C per minute and a dead zone of 1°C.

On the basis of referring to Figure 1, we assume for this particular detector that the temperature stored in the data memory prior to time _t0 is 57.4°C. When the detector is scanned at time _t0 , it shows a temperature of 57.5°C. Since the difference is only 0.1°C, the temperature value 57.5°C at time _t0 will not be stored, because in this example, the difference does not exceed the preset dead zone of 1°C. For example, maybe after 5 seconds, there is another scan, and the output of the detector is read, which shows a temperature value of 58.1°C. This temperature value is compared with the last stored temperature value of 57.4°C, and the resulting difference is 0.7°C, so it will not be stored.

At time _t2 , its temperature is 58.5°C, compared to the last stored temperature value of 57.4°C, there is a difference of 1.1°C, so the temperature value of 58.5°C and time _t2 are stored in Data memory 18 has gone. Now, the temperature value of 58.5°C becomes the previous stored value for subsequent readings, and the reading at time _t3 is 59.2°C, which only produces a difference of 0.7°C, and as a result, no action will take place. At time _t4 , the temperature is 60.5°C, which produces a difference of 2°C compared with the last stored temperature value of 58.5°C. 2°C exceeds the dead zone of 1°C, so this time and temperature value will be stored. In addition, the upper threshold value of 60°C has been exceeded at this time, so the data link between the equipment and the diagnostic center will be started, and all data in the memory 18 will be sent immediately, so that the diagnostic center can complete a diagnosis by means of a computer 32 analyze.

Since the threshold level has been exceeded, data acquisition computer 16 then sets a new threshold level. For example, let this new threshold level be 3°C higher than the original threshold level, or set at 63°C. Furthermore, it should be noted that at time _t5 , the temperature value of 60.5°C is obtained, which exceeds the limit of the rate of change of 20°C per minute, and it will also indicate to send the stored data immediately.

At time _t5 , because the limit level is not exceeded, no action will take place; and at time _t6 , because the dead zone of 1°C is exceeded, the temperature value of 62°C and time _t6 are stored.

At time _t7 , the temperature value is 62.9°C, so no action will take place; and at time _t8 , the temperature reaches 63.5°C, because it exceeds the dead zone and its second threshold level, so the instruction The stored data is sent to the diagnosis center in real time.

In addition, the data acquisition computer 16 designates a new threshold level, 66° C., which is 3° C. higher than the threshold set last time. from t ₈ to t ₉ . The temperature has increased by 0.5°C, so nothing happens; and at time t ₁₀ , the temperature reaches 65.2°C. Since the deadband has been exceeded, the time and temperature values are stored. In addition, since the rate of change limit of 20°C per minute was exceeded, the command data link was immediately activated to transmit the stored information.

The table below gives an overview of the above working process.

(1) Do nothing.

(2) Storage time and temperature values.

(3) Start the data link to the diagnostic center.

(4) Set a new limit level.

Now that the case of a rise in temperature of a single temperature probe has been described, the rationale for applying it to the case of temperature fall is also understood. Among them, if the original lower limit level is exceeded, a new, lower limit level is set. Now that the relationship of one temperature probe with time is described, the same principle can be applied to other probes. These detectors can be scanned with a scan period of 5 seconds as shown in Fig. 2, or with a period shorter or longer than 5 seconds.

In FIG. 3, a flowchart illustrating the operation of the data collection computer 16 on the device 2 is illustrated. Through the operation of block 50, the data acquisition computer 16 will scan the output of each detector and perform necessary preprocessing on these output signals, such preprocessing includes signal trimming, normalization, averaging, digital-to-analog conversion, Certain quantities are converted to engineering units. The signal from each detector is compared with the last stored value to see if the specified deadband has been exceeded for a particular detector. If the decision block 52 indicates that it has been exceeded, then the new value of the detector is stored in the limited data memory 18 as indicated by the block 54 . If the deadband has not been exceeded, then as indicated by decision block 56, a determination is made as to whether any diagnostic activation limit level has been exceeded. This limit can be a threshold limit or a rate-of-change limit, as described above. This process also will be carried out according to the data stored as the result of the operation of frame 54; wherein, as indicated by decision block 58, if an equipment is not in alert-working (ALERT-ACTIVE) state , will be judged by Block 56 checks the stored data to see if the threshold for diagnostic activation has been exceeded.

Decision block 60 determines whether it is now the sending time according to the plan, such as every hour; if not, then return to point A to repeat the process. If it is the time to send, then as indicated by block 62, a communication link is open to the diagnostic center. If the result of frame 56 judgment has exceeded the limit level of diagnostic initiation, this communication link is also opened, in this case, as indicated by frame 64, will exceed this limit level one or more The time and value of each detector are stored.

Once this communication link is opened, as indicated by block 66, all data stored since the last transmission will be sent to the diagnostic center for analysis. If the device is in an ALERT-ACTIVE state, any new data stored as a result of block 54 will be sent immediately as a result of decision block 58.

Once the diagnosis is complete, the diagnostic center can send information back to the device related to the status of the device, such as what actions the operator should take, what changes to make, and so on. Accordingly, block 68 ensures that any results received from the diagnostic center are displayed on the operator terminal 40 of the facility.

FIG. 4 shows a flow chart of the operation of the diagnosis center computer 32 . Depending on the type of equipment and the different equipment being diagnosed, block 80 will ensure that appropriate diagnostic procedures or ground rules are preset for an expert system. Box 82 indicates receiving data transmitted from a device, and box 84 indicates that diagnostic analysis may be performed.

Through the operation of square box 86, the result of diagnostic analysis and the data of this detector are all stored up, and make judgment by decision box 88, whether should preset alert state as analysis result. If the decision indicates that the alert state is to be preset, block 90 will issue an instruction to place the device in an alert-active state. If the result of the determination is not to preset the alert state, block 92 will issue an instruction, for example, to place the device in an OK (normal) state, or in a CONCERN (connected) state.

At first, a timer function is set up in the computer, if it is indicated to be in an alert-work (ALERT-ACTIVE) state, as indicated in block 94, the timer is set on a certain predetermined time interval, such as 15 Minutes, if do not indicate to be in alert-work (ALERT-ACTIVE) state, as indicated in square frame 96, timer is set to zero.

Although diagnostic results are available at the diagnostic center, authorization must be granted for the results to be returned to the device. A transmit location can be entered into the computer program; therefore, if decision block 100 indicates that, for the particular device, a transmit bit or transmit flag is set, then as indicated in block 102 In that way, the diagnostic result is returned to the device. This transmission cannot only include the status of the device, as a result of a diagnosis, some commands can be sent to change some parameters, for example, the width of the dead zone, the threshold or the rate of change limit. The analysis may indicate that more data should be sent, in which case the dead zone can be narrowed, or the start limit level can be lowered. Conversely, if the diagnostic result shows that there is actually no fault and too much data is being sent, then the dead zone can be widened and the start limit can be increased.

If the send flag is not set for a particular device, it should be noted that there are certain things to be checked further by personnel at the diagnostic center before the appropriate command is sent. In either case, decision block 104 checks the timer to see if the timer is zero. If the timer is set to zero, or is decremented to zero from its previously set value, then as indicated by block 106, the communication link with the device is disconnected. If the timer is not zero, it is determined by decision block 108 whether new data has been received from the device, and if so, by setting the timer indicated by block 110, the communication link is at least another 15 The minute period is kept open. If do not receive any new data all the time, just can pass through the operation of box 112, reduce this timer, if in the time period of 15 minutes, do not receive any new data all the time, timer will be reduced to zero , in which case the communication link with the device is broken.

Therefore, we describe a diagnostic system comprising a diagnostic center for complex diagnostic analysis devices, which can analyze one or more process devices located in an entire country or an entire world region. Each facility will have a relatively inexpensive data collection system for scheduled periodic transmissions to the diagnostic center. Depending on the occurrence of certain conditions, this periodic transmission will be interrupted in order to complete the immediate transmission of some data, so that the transmission of data and diagnostic processing can be reduced to a minimum while still providing accurate information for each device. accurate and timely diagnosis. The diagnostic center can remotely change any transmission cycle that has been established, as well as other parameters, such as dead zone and start limit level, in order to The system gives both flexible and centralized routing control.

surface time temperature The last stored temperature value difference New stored temperature value Is it more than action dead zone threshold level rate of change limit t ₀ t ₁ t ₂ t ₃ t ₄ t ₅ t ₆ t ₇ t ₈ t ₉ t ₁₀ 57.558.158.559.260.561.062.062.963.564.065.2 57.457.457.458.558.560.560.562.062.063.563.5 0.10.71.10.72.00.51.50.91.50.51.7 57.457.458.558.560.560.562.062.063.563.565.2 no no yes yes no no no no no no no no no no no No No No No No No No No No No Yes (1)(1)(2)(1)(2)(3)(4)(1)(2)(1)(2)(3)(4)(1)(2)(3)

Claims (15)

1. A diagnostic system for monitoring a process at a first positioning position. The process includes a plurality of detectors that generate output signals related to the working state of the process. The diagnostic system includes, located at the first positioning position First data storage means, first computing means at said first location, first transmitter/receiver means at said first location, said first computing means being able to cycle the output signal of said detector and those signals which show a predetermined difference in value and those signals which exceed respective predetermined thresholds compared with the previous scan are stored in the above-mentioned first data storage means, and the first transmitter / The receiver device is controlled by the above-mentioned first computer device, and also includes a diagnostic center at a second location away from the above-mentioned first location, and a second computing device capable of performing diagnostic analysis and a second data storage device and a second Transmitter/receiver means, the second transmitter/receiver means receiving data sent from said first location location under the control of said second computing means, a diagnostic analysis being performed by said second computing means, characterized in In that, the first transmitter/receiver device sends the contents of the first data storage device to the diagnostic center through the data link within a prearranged time period, and whenever a signal exceeds its The above-mentioned content is sent out within a period of time not determined in advance, and the above-mentioned second transmitter/receiver device can also be used to send the result information of the above-mentioned analysis back to the first transmitter/receiver through the above-mentioned data link means, the above-mentioned first transmitter/receiver means may also be used to receive information transmitted therefrom. 2. The system according to claim 1, characterized in that the system includes a display device for displaying the received transmission information at the first positioning position, and wherein the first computing device and the second The computing devices are composed of a first computer device and a second computer device, respectively. 3. A system as claimed in claim 1 or 2, characterized in that the contents of said first data storage means are transmitted upon occurrence of a detector signal exceeding a predetermined threshold level. 4. The system of claim 3, wherein said first computing means is capable of assigning a new threshold level when an old threshold level is exceeded. 5. A system according to any one of claims 1 or 3, characterized in that the contents of said first data storage means are transmitted upon occurrence of a detector signal exceeding a predetermined rate-of-change limit . 6. The system of claim 5 wherein said rate of change limit is greater than said predetermined difference. 7. A system according to any one of claims 1 or 6, wherein said first computing means is operable to vary said predetermined difference in response to instructions from said second computing means. 8. A system according to any one of claims 1 or 3, wherein the data link is kept open for a predetermined period of time if the result of said diagnostic analysis indicates an abnormal condition. 9. The system of claim 8, wherein said predetermined period of time for keeping the data link open is shorter than the time period between scheduled transmissions of the contents of said first data storage means. 10. The system of claim 8 wherein said data link means automatically terminates if no new data is transmitted during said predetermined period of time during which said data link is kept open. 11. The system of claim 9, wherein said data link means automatically terminates if no new data is transmitted during said predetermined period of time during which said data link is kept open. 12. The system of claim 1, wherein the results of said diagnostic analysis are first displayed at said second location before being returned to said first location. 13. The system according to claim 1, characterized in that the above-mentioned process is a power generation process, and the process includes at least one generator, an exciter for feeding excitation current to the generator, and an exciter for The steam turbine that drives the generator. 14. The system according to claim 12, characterized in that the system comprises a plurality of detectors for measuring the working state of the generator, a plurality of detectors for measuring the working state of the exciter and a plurality of detectors for Probes for measuring the operating state of the above mentioned steam turbines. 15. The system according to claim 1, characterized in that, the system includes one or more other locations away from the diagnostic center, each of the other locations includes: a data storage device; a computer device, the device capable of periodically scanning the output signals of the detector and storing in its data storage means those signals which exhibit a predetermined difference in value compared with the previous scan and those signals which exceed respective predetermined thresholds; and A transmitter/receiver device which, under the control of said computer device, transmits the contents of said data storage device to said diagnostic center via a data link within a pre-installed time period, and whenever , which is sent for an undetermined period of time whenever a signal exceeds its predetermined threshold.

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