Experimental device for on-line monitoring of LVDT redundancy function of steam turbine valve

Abstract

The invention relates to an experimental device for monitoring the redundancy function of an LVDT (Linear Variable Differential Transformer) of a steam turbine valve on line. The experimental device comprises a core control and processing unit, a signal access and conditioning module, an intelligent fault injection and switching simulation module, a communication interface module and a man-machine interaction module, the core control and processing unit is connected with the signal access and conditioning module, the intelligent fault injection and switching simulation module, the communication interface module, the data recording and playback module and the man-machine interaction module through a high-speed parallel bus. The core control and processing unit carries out overall planning and scheduling on all the modules and carries out data processing. The comprehensive and real online test of the LVDT redundant system is realized, the safe operation of a unit is not influenced by the online test, the risk is reduced to the minimum, and a solid basis is provided for fault analysis.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and in particular to an experimental device for online monitoring of the LVDT redundancy function of steam turbine valves. Background Technology

[0002] Steam turbines are core power equipment in industrial sectors such as thermal power generation and nuclear power generation, and their safe and stable operation is of paramount importance. Steam turbine regulating valves are key actuators that control steam flow, thereby regulating unit load and speed; their accuracy and reliability directly affect the safety of the entire unit. Linear variable differential transformers (LVDTs), as the core sensors for measuring valve opening, typically employ redundant configurations (such as dual-channel or two-out-of-three designs). This is designed so that when a single LVDT fails, the system can seamlessly switch to the backup channel to maintain normal valve control. To ensure reliable switching of the redundant LVDT system at critical moments, regular functional testing is an essential maintenance step.

[0003] Existing LVDT redundancy testing methods and devices have significant limitations, mainly in the following aspects: First, the realism and comprehensiveness of the tests are insufficient. Most existing technologies can only simulate "hard faults" of LVDTs, such as complete disconnection or short circuit of signal lines. However, in actual operation, LVDTs are more commonly subject to "soft faults" of gradually deteriorating performance, such as poor signal linearity and zero-point drift due to coil aging and core wear, or signal-to-noise ratio degradation and intermittent signal abnormalities caused by electromagnetic interference. Existing devices cannot simulate these complex soft fault scenarios, resulting in the inability to fully verify the switching performance and signal quality of the backup LVDT under incomplete failure conditions, leaving potential safety hazards. Second, the safety and intelligence level of the testing process are low. Traditional testing methods rely heavily on the experience of operators, and the timing and safety judgment of tests are highly subjective. Although some devices have set fixed safety thresholds, they lack the ability to dynamically perceive and adaptively judge the real-time operating conditions of the unit, and cannot automatically conduct tests within the optimal safety window. At the same time, the fault injection method is often relatively crude, which may cause instantaneous impact on the valve servo control system and cause unit disturbance. Furthermore, the testing process lacks multi-layered, automated safety interlock protection. In the event of an unexpected situation during testing, the system cannot be quickly stopped and restored, posing a high risk. Secondly, it lacks condition monitoring and predictive maintenance capabilities. The existing equipment's function is limited to "periodic testing," rather than "continuous monitoring." It cannot track, record, and deeply analyze long-term LVDT operating data, cannot quantitatively assess the health status of each LVDT channel (such as consistency, linearity, and stability), and cannot predict its remaining service life based on data trends. This keeps equipment maintenance in a passive mode of "retrofit repair" or "periodic replacement," failing to upgrade to "predictive maintenance," increasing the risk of sudden failures and potentially leading to unnecessary waste of spare parts. Finally, data traceability and system reliability need improvement. When anomalies occur during testing, existing equipment typically lacks high-precision, full-process data recording and playback capabilities, hindering root cause analysis. Simultaneously, at the hardware level of signal processing and fault injection, inter-channel interference may exist, affecting test accuracy; the reliability of the power supply system is often overlooked, and fluctuations or momentary interruptions in external power can lead to data loss or even equipment malfunction. Summary of the Invention

[0004] To address the limitations of existing LVDT redundancy test devices, this invention proposes the following technical solution: An experimental device for online monitoring of the LVDT redundancy function of steam turbine valves includes a core control and processing unit, a signal access and conditioning module, an intelligent fault injection and switching simulation module, a communication interface module, and a human-computer interaction module; characterized in that: The core control and processing unit is connected to the signal access and conditioning module, intelligent fault injection and switching simulation module, communication interface module, data recording and playback module, and human-machine interaction module via a high-speed parallel bus. The core control and processing unit coordinates and processes the data of each module. The signal access and conditioning module is connected to the LVDT sensor on the turbine valve to collect and process multiple redundant LVDT signals. The LVDT signal is input to the operating condition sensing module in the core control and processing unit. After signal processing, the turbine operating parameters can be obtained in real time. The intelligent fault injection and switching simulation module receives control from the core control and processing unit to inject fault signals and introduces the fault signals into the valve control system.

[0005] Furthermore, the human-machine interaction module is used for parameter configuration and result display; the communication interface module realizes data exchange with the power plant's DCS and information management system, and can obtain relevant control command data and transmit it to the operating condition sensing module; the data recording and playback module is connected to a memory for storing and playing back experimental data for analysis.

[0006] Furthermore, the core control and processing unit consists of an embedded industrial motherboard or a high-performance FPGA / ARM architecture processor, which is responsible for the scheduling, calculation and decision-making of the entire system.

[0007] Furthermore, the signal access and conditioning module has an independent hardware channel architecture, providing an independent hardware channel for each redundant LVDT signal of the turbine valve.

[0008] Furthermore, the signal access and conditioning module provides multiple identical, isolated, parallel processing circuit boards or channel units; each channel unit includes an isolation amplifier, a low-pass filter, and an analog-to-digital converter.

[0009] Furthermore, the experimental setup is equipped with dynamic safety operation window management and test trigger management; The device first injects a standard reference signal into the signal acquisition link through a self-calibration circuit to automatically calibrate the gain and offset of each acquisition channel to ensure measurement accuracy. At the same time, it dynamically compares the real-time parameters of the unit obtained by the operating condition sensing module with the preset safety threshold, and determines the safe operation window status through logical judgment, thereby deciding whether to allow the test to start, thus achieving safety assurance before the test.

[0010] Furthermore, the experimental setup is equipped with parameterized soft fault simulation and progressive injection procedures; Within the safe operation window, the core control and processing unit controls the fault injection module to gradually increase the fault deviation from zero to the target value according to the configured fault mode parameters, simulating the soft fault process and minimizing the instantaneous impact on the valve control system. At the same time, the process also covers the complete steps of test triggering, signal injection, data acquisition and result generation.

[0011] Furthermore, the experimental setup is equipped with full-process data recording and redundancy switching analysis; During the fault injection test, the core control unit monitors the signal characteristics of each LVDT channel and the switching status of the control system in real time, calculates the switching response time and success rate, and ensures the safety and reliability of the test process through multi-level safety interlocking logic, including the first-level interlocking based on the operating condition parameters to lock the test start, and the second-level interlocking to immediately stop the injection when the valve action is abnormal or the backup channel fails.

[0012] Furthermore, the experimental setup is equipped with long-term health status assessment and predictive maintenance; Based on long-term monitoring data, the core control unit periodically calculates the consistency index, linearity error and signal stability index of each LVDT channel, and uses machine learning algorithms to analyze the performance degradation trend, establishes a predictive model to estimate the remaining service life, and provides proactive warnings when the index exceeds the threshold or the service life is near, thus realizing the transformation from passive maintenance to predictive maintenance.

[0013] Furthermore, the experimental setup is equipped with test report generation and data traceability functions; After the test, the core control and processing unit will automatically organize all relevant data and generate a structured test report. The report includes: test time, the valve under test and the LVDT channel, the injected fault modes and parameters, safety window conditions, measured switching response time, redundancy switching conclusions, and the maximum valve disturbance during the test.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Intelligent Fault Injection and Parametric Soft Fault Simulation: The intelligent fault injection module can simulate various soft faults, including signal drift, noise interference, and intermittent interruptions, and the fault parameters (such as drift rate / amplitude, signal-to-noise ratio / frequency, and interruption duration / interval) can be flexibly configured. This overcomes the limitation of existing technologies that can only simulate hard faults, enabling more comprehensive and realistic online testing of LVDT redundant systems.

[0015] 2. Dynamic safety strategy based on real-time operating condition perception and multi-level safety interlocks: The operating condition perception module acquires unit operating parameters in real time, and the core control unit dynamically determines the "safe operation window" as a prerequisite for the test (first-level interlock); during the test, valve actions and the status of the backup LVDT channel are monitored in real time, and fault injection is immediately stopped if the limits are exceeded (second-level interlock). This collaborative mechanism ensures that online testing does not affect the safe operation of the unit and minimizes risks.

[0016] 3. Online health status assessment and lifespan prediction of LVDT: Based on long-term monitoring data, the system automatically calculates health indicators such as consistency, linearity and stability of LVDT channels, and uses machine learning algorithms to establish a performance degradation model to predict and provide early warning of remaining service life, thereby promoting the transformation of maintenance mode from passive inspection to proactive prediction.

[0017] 4. Independent Hardware Channels and Electrical Isolation Design: The signal input and conditioning module and the fault injection module each employ an independent hardware channel for processing each LVDT signal. Electrical isolation between channels is achieved using isolation amplifiers or digital isolators. This fundamentally avoids mutual interference between channels, ensuring the accuracy and reliability of fault injection and signal monitoring.

[0018] 5. Integrated self-calibration and full-process data recording and playback: The device has a built-in self-calibration circuit that can automatically calibrate the accuracy of the entire signal acquisition link periodically or before the test, ensuring data accuracy. Simultaneously, it integrates a data recording and playback module, which can continuously record data throughout the entire test process and save data before and after the trigger point in case of anomalies, providing a solid basis for fault analysis. Attached Figure Description

[0019] Figure 1 System overall architecture and data flow diagram; Figure 2 Flowchart for self-calibration and safe operation window judgment; Figure 3 Flowchart of progressive fault injection and testing; Figure 4 Redundancy switching verification and safety interlocking logic diagram; Figure 5 : Flowchart of LVDT health status assessment and prediction. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0021] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is described as "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is described as "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," "top," "bottom," and similar expressions used in this document are for illustrative purposes only.

[0022] Please see Figures 1-5 This invention discloses an online monitoring device for the LVDT redundancy function of steam turbine valves. This embodiment aims to provide a specific implementation of a device capable of online, safe, comprehensive, and intelligent monitoring and testing of the LVDT redundancy function of steam turbine valves.

[0023] See Figure 1 An experimental device for online monitoring of the redundancy function of turbine valves using an LVDT (Low Voltage Detector) includes a core control and processing unit, a signal access and conditioning module, an intelligent fault injection and switching simulation module, a communication interface module, and a human-machine interaction module.

[0024] The core control and processing unit, consisting of an embedded industrial motherboard or a high-performance FPGA / ARM architecture processor, is responsible for the scheduling, calculation, and decision-making of the entire system. This unit is connected to the signal access and conditioning module, intelligent fault injection and switching simulation module, communication interface module, data recording and playback module, and human-machine interaction module via a high-speed parallel bus. The core control and processing unit coordinates and processes data from each module.

[0025] The signal access and conditioning module is connected to the LVDT sensor on the turbine valve to collect and process multiple redundant LVDT signals. The LVDT signal is input to the operating condition sensing module in the core control and processing unit. After signal processing, the turbine operating parameters can be obtained in real time. The intelligent fault injection and switching simulation module receives control from the core control and processing unit to inject fault signals and introduce them into the valve control system. The human-machine interface module is used for parameter configuration and result display; the communication interface module enables data exchange with the power plant's DCS and information management system, and can acquire relevant control command data and transmit it to the operating condition sensing module. The data recording and playback module is connected to a memory for storing and replaying experimental data for analysis.

[0026] This experimental setup constructs a complete data closed loop from signal input to intelligent diagnosis and output.

[0027] The signal access and conditioning module has an independent hardware channel architecture, providing an independent hardware channel for each redundant LVDT signal of the turbine valve (e.g., three channels: LVDT1, LVDT2, LVDT3). Specifically: The signal input and conditioning module physically provides three identical, isolated, parallel processing circuit boards or channel units. Within each channel unit, the signal first enters an electrical isolation unit implemented by an isolation amplifier (such as Analog Devices' AD210 series). This isolation amplifier establishes a complete electrical barrier, with key parameters including an isolation voltage of at least 2500Vrms and a common-mode rejection ratio (CMRR) of at least 120dB. Even if a high voltage is introduced into one LVDT channel due to insulation failure in the field, it cannot be transmitted to other LVDT channels or the core control system through this device. This "one channel per channel, channel isolation" design is the physical basis for ensuring the accuracy and reliability of fault injection and signal monitoring, avoiding mutual interference between channels, and protecting subsequent circuits.

[0028] The isolated signal passes through a low-pass filter with a configurable cutoff frequency to remove high-frequency noise. Finally, a high-precision analog-to-digital converter converts the analog signal into a digital signal at a sampling rate of no less than 100kSPS, which is then provided to the core control and processing unit for reading.

[0029] See Figure 2 The experimental setup is equipped with dynamic safety operation window management and test trigger management; The device first injects a standard reference signal into the signal acquisition link through a self-calibration circuit to automatically calibrate the gain and offset of each acquisition channel to ensure measurement accuracy. At the same time, it dynamically compares the real-time unit parameters (such as load and main steam pressure) obtained by the operating condition sensing module with the preset safety threshold, and determines the safe operation window status through logical judgment, thereby deciding whether to allow the test to start, thus achieving safety assurance before the test.

[0030] Specifically, During normal operation, the core control and processing unit continuously acquires unit parameters through the operating condition sensing module. Meanwhile, the operators have pre-set the safety thresholds for allowing LVDT tests through the human-machine interface module, such as the load range. , Main steam pressure upper limit These thresholds are stored in the non-volatile memory of the core control and processing unit.

[0031] The core control and processing unit executes a dynamic judgment algorithm, the logical expression of which is as follows: IF (Other parameter judgment) THEN Safe running window status = TRUE ELSE Safe Run Window Status = FALSE END IF.

[0032] This dynamic judgment logic is the first level of safety interlock in the multi-level safety interlock logic preset within the core control and processing unit. The "Start Test" button on the human-machine interface will only be enabled when the safety operation window status is TRUE, allowing the operator to proceed. Otherwise, the button will be disabled, fundamentally preventing the start of the test under hazardous conditions.

[0033] See Figure 3 The experimental setup is equipped with parameterized soft fault simulation and progressive injection procedures. Within the safe operation window, the core control and processing unit controls the fault injection module to gradually increase the fault deviation from zero to the target value according to the configured fault mode (such as signal drift and noise interference) parameters, simulating the soft fault process and minimizing the instantaneous impact on the valve control system. At the same time, the process also covers the complete steps of test triggering, signal injection, data acquisition and result generation.

[0034] When the operator selects to test the LVDT1 channel on the Human-Machine Interface (HMI) module, and sets various fault modes that can be simulated (such as signal drift fault, drift rate) from the Intelligent Fault Injection and Switching Simulation Module, The target drift is 10 mV / s. After setting the voltage to 100 mV, the core control and processing unit, upon confirming the safety window is open, issues a command to the intelligent fault injection module. Similarly, for noise interference faults, the signal-to-noise ratio (SNR) and noise frequency can be set; for intermittent interruption faults, the duration of the signal interruption and the interval between two interruptions can be set. All fault simulation parameters are configured through the human-machine interface module and, after being parsed by the core control and processing unit, control the intelligent fault injection and switching simulation module to generate the corresponding fault signal waveform.

[0035] During fault injection, the judgment logic of monitoring switching conditions and safety interlocks is executed. If signal injection and switching occur safely, the test continues and a report is generated. If the safety interlock is triggered, the test is stopped and the original real signal is restored.

[0036] See Figure 4 The experimental setup is equipped with full-process data recording and redundancy switching analysis. During the fault injection test, the core control unit monitors the signal characteristics of each LVDT channel and the switching status of the control system in real time, accurately calculates the switching response time and success rate, and ensures the safety and reliability of the test process through multi-level safety interlocking logic (such as the first-level interlocking based on the operating condition parameters to lock the test start, and the second-level interlocking to immediately stop the injection when the valve action is abnormal or the backup channel fails).

[0037] From the moment the test command is issued, the data recording and playback module, integrated within the core control and processing unit and using a high-speed solid-state drive as the storage medium, begins operation. By creating a circular buffer on the high-speed storage medium (e.g., using a first-in, first-out data queue, with a capacity to store the most recent 30 minutes of full-rate data), it continuously records the following data: the raw signals from three LVDTs. and post-injection signal Valve servo control commands and data obtained from DCS and All data is time-stamped, and the sampling rate is synchronized with the signal acquisition module.

[0038] The core control and processing unit synchronously performs redundancy switching verification and monitors the status word of the valve control system in real time (read from the DCS through the communication interface module). This status word indicates which LVDT signal is currently being used for valve control.

[0039] See Figure 5 The experimental setup is equipped with long-term health status assessment and predictive maintenance. Based on long-term monitoring data, the core control unit periodically calculates the consistency index, linearity error and signal stability index of each LVDT channel, and uses machine learning algorithms to analyze the performance degradation trend, establishes a predictive model to estimate the remaining service life, and provides proactive warnings when the index exceeds the threshold or the service life is near, thus realizing the transformation from passive maintenance to predictive maintenance.

[0040] During long-term online operation of the device, the core control and processing unit utilizes idle computing resources to perform LVDT health status assessment and prediction functions. It periodically (e.g., once per hour) extracts synchronized data from the three LVDTs from the historical database for analysis and processing.

[0041] Furthermore, the experimental setup is equipped with test report generation and data traceability functions; After the test, the core control and processing unit will automatically organize all relevant data and generate a structured test report. The report includes: test time, the tested valve and LVDT channel, injected fault modes and parameters, safety window conditions, and measured switching response time. The report includes information such as redundancy switching conclusions and maximum valve disturbance during the test. It is displayed through a human-machine interface module and automatically uploaded to the power plant information management system for archiving via the communication interface module.

[0042] If a safety interlock is triggered or any anomaly occurs during the test, engineers can access the data recording and playback module through the human-machine interface module. This module copies high-resolution data from the circular buffer to storage (a specific directory on the hard drive) for a period of time before and after the marked anomaly point (e.g., 10 seconds before and 5 seconds after), generating a unique filename associated with the test report. Engineers can use the built-in waveform browsing tool to simultaneously replay waveforms of multiple signals, zoom, compare, and measure them, thereby accurately analyzing the cause of the anomaly and completing the root cause investigation.

[0043] Finally, it should be noted that the above description is merely an explanation of the present invention and is not intended to limit the invention. Although the present invention has been described in detail, those skilled in the art can still modify the technical solutions described above or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An experimental device for online monitoring of the LVDT redundancy function of steam turbine valves, comprising a core control and processing unit, a signal access and conditioning module, an intelligent fault injection and switching simulation module, a communication interface module, and a human-machine interaction module; characterized in that: The core control and processing unit is connected to the signal access and conditioning module, intelligent fault injection and switching simulation module, communication interface module, data recording and playback module, and human-machine interaction module via a high-speed parallel bus. The core control and processing unit coordinates and processes the data of each module. The signal access and conditioning module is connected to the LVDT sensor on the turbine valve to collect and process multiple redundant LVDT signals. The LVDT signal is input to the operating condition sensing module in the core control and processing unit. After signal processing, the turbine operating parameters can be obtained in real time. The intelligent fault injection and switching simulation module receives control from the core control and processing unit to inject fault signals and introduces the fault signals into the valve control system.

2. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The human-machine interaction module is used for parameter configuration and result display; the communication interface module realizes data exchange with the power plant's DCS and information management system, and can obtain relevant control command data and transmit it to the operating condition sensing module; the data recording and playback module is connected to a memory for storing and playing back experimental data for analysis.

3. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The core control and processing unit consists of an embedded industrial motherboard or a high-performance FPGA / ARM architecture processor, and is responsible for the scheduling, calculation and decision-making of the entire system.

4. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The signal access and conditioning module has an independent hardware channel architecture, providing an independent hardware channel for each redundant LVDT signal of the turbine valve.

5. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 4, characterized in that, The signal access and conditioning module provides multiple identical, isolated, parallel processing circuit boards or channel units; each channel unit includes an isolation amplifier, a low-pass filter, and an analog-to-digital converter.

6. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The experimental setup is equipped with dynamic safety operation window management and test trigger management; The device first injects a standard reference signal into the signal acquisition link through a self-calibration circuit to automatically calibrate the gain and offset of each acquisition channel to ensure measurement accuracy. At the same time, it dynamically compares the real-time parameters of the unit obtained by the operating condition sensing module with the preset safety threshold, and determines the safe operation window status through logical judgment, thereby deciding whether to allow the test to start, thus achieving safety assurance before the test.

7. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The experimental setup is equipped with parameterized soft fault simulation and progressive injection procedures. Within the safe operation window, the core control and processing unit controls the fault injection module to gradually increase the fault deviation from zero to the target value according to the configured fault mode parameters, simulating the soft fault process and minimizing the instantaneous impact on the valve control system. At the same time, the process also covers the complete steps of test triggering, signal injection, data acquisition and result generation.

8. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The experimental setup is equipped with full-process data recording and redundancy switching analysis; In the fault injection test, the core control unit monitors the signal characteristics of each LVDT channel and the switching status of the control system in real time, and calculates the switching response time and success rate. The test process is ensured by a multi-level safety interlocking logic, including a first-level interlocking based on operating parameters to start the test and a second-level interlocking to immediately stop the injection when the valve operates abnormally or the backup channel fails.

9. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The experimental setup is equipped with long-term health status assessment and predictive maintenance. Based on long-term monitoring data, the core control unit periodically calculates the consistency index, linearity error and signal stability index of each LVDT channel, and uses machine learning algorithms to analyze the performance degradation trend, establishes a predictive model to estimate the remaining service life, and provides proactive warnings when the index exceeds the threshold or the service life is near, thus realizing the transformation from passive maintenance to predictive maintenance.

10. The experimental device for online monitoring of the LVDT redundancy function of turbine valves according to claim 1, characterized in that, The experimental setup is equipped with test report generation and data traceability; After the test, the core control and processing unit will automatically organize all relevant data and generate a structured test report. The report includes: test time, the valve under test and the LVDT channel, the injected fault modes and parameters, safety window conditions, measured switching response time, redundancy switching conclusions, and the maximum valve disturbance during the test.

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