An LVDT measuring device

Abstract

This invention provides an LVDT (Low Volume Demand) measuring device, relating to the field of sensor measurement technology. It includes: at least one pair of LVDT sensors, each installed on a different valve to convert the acquired valve mechanical displacement into an electrical signal; a control module that controls the LVDT sensors by setting different control units, with each LVDT sensor connected to a control unit via a control cable; and a joint control unit that jointly controls each LVDT sensor; the joint control unit is also connected to a monitoring unit. This invention, by setting at least one pair of LVDT sensors and corresponding control units, forms a multi-loop control architecture, avoiding the problem of valve malfunction due to a single point of failure in traditional single-loop structures, and significantly reducing the overall system failure probability.

Description

Technical Field

[0001] This utility model relates to the field of sensor measurement technology, specifically to an LVDT measuring device. Background Technology

[0002] In existing steam turbine valve control systems, the control architecture for the main steam valve, high-pressure regulating valve, and intermediate-pressure regulating valve is typically based on a single-loop structure. Each valve is equipped with a VCC card and a linear variable differential transformer (LVDT), which poses a high risk of single-point failure. In current control systems, both the VCC card and the LVDT are individual devices controlling the position of the corresponding valve. If any component fails, such as a VCC card malfunction or an LVDT wears out, it will directly cause the valve to lose effective closed-loop control, potentially leading to abnormal valve actions, such as sudden full opening or full closing. This not only threatens the stable operation of the steam turbine but may also lead to serious safety accidents. Therefore, this invention proposes an LVDT measuring device to improve the above-mentioned problems. Utility Model Content

[0003] Therefore, the technical problem to be solved by this utility model is to overcome the high risk of single-point failure in the existing LVDT measuring device, thereby providing an LVDT measuring device.

[0004] To address the above problems, this utility model provides an LVDT measuring device, which includes:

[0005] At least one pair of LVDT sensors are installed on different valves to convert the acquired valve mechanical displacement into electrical signals;

[0006] The control module controls and measures the LVDT sensors by setting different control units, and each LVDT sensor is connected to the control unit via a control cable; a joint control unit performs joint control of each LVDT sensor; the joint control unit is also connected to a monitoring unit.

[0007] Preferably, each LVDT sensor is configured with redundancy. The LVDT sensor includes: a main measurement module for daily monitoring of valve position; and a backup measurement module, which the control unit automatically switches to when the main measurement device malfunctions or the deviation exceeds a preset value.

[0008] Preferably, the monitoring unit is configured with monitoring logic by the control unit: based on real-time signal comparison, it is used to continuously compare the output signals of the two LVDT sensors with a preset threshold.

[0009] Preferably, it further includes: an alarm module, which is connected to the monitoring unit and is used to trigger an alarm when the threshold of the alarm module is greater than a preset threshold.

[0010] Preferably, the control cable is a twisted pair cable with a shielded layer, the shielded layer is grounded at one end to suppress electromagnetic interference, the cable outer diameter is 6-8mm and can withstand an ambient temperature of -40℃ to 125℃.

[0011] Preferably, the control module further includes a data storage unit and a communication interface. The data storage unit can store at least 3 months of measurement data, and the communication interface supports Modbus or Profibus protocols to enable data interaction with the host computer.

[0012] Preferably, the monitoring logic further includes a signal trend analysis function, which triggers a pre-alarm state and records the change curve when the rate of change of five consecutive measurements exceeds a preset slope threshold.

[0013] Preferably, the LVDT sensor is fixed to the valve body by an adjustable bracket with an adjustment range of ±15mm to compensate for installation errors. The connection end between the sensor and the valve adopts a ball joint structure to accommodate the slight deflection of the valve.

[0014] Preferably, the system further includes a redundant power supply module, which provides dual independent power supplies for the control module and the LVDT sensor. When the main power supply voltage fluctuates by more than ±10%, it automatically switches to the backup power supply with a switching time of less than 5ms.

[0015] The LVDT measuring device provided by this utility model has the following beneficial effects:

[0016] 1. This utility model forms a multi-loop control architecture by setting at least one pair of LVDT sensors and corresponding control units, which avoids the problem of valve malfunction caused by single-point failure in the traditional single-loop structure and significantly reduces the overall failure probability of the system.

[0017] 2. This utility model also adopts a primary and backup redundant configuration for each LVDT sensor. When the primary measurement module fails or the deviation exceeds the preset value, the control unit automatically switches to the backup module to ensure the continuity of valve position measurement and ensure the stable operation of the steam turbine. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the architecture of this utility model. Detailed Implementation

[0019] like Figure 1 As shown, this utility model provides an LVDT measuring device, which includes:

[0020] At least one pair of LVDT sensors are respectively installed on different valves to convert the acquired valve mechanical displacement into electrical signals; a control module controls and measures the LVDT sensors by setting different control units, and each LVDT sensor is connected to the control unit via a control cable; a joint control unit performs joint control of each LVDT sensor; the joint control unit is also connected to a monitoring unit. Figure 1 As shown, the LVDT measuring device of this invention is mainly applied to the valve control system of a steam turbine, aiming to solve the single-point failure risk problem existing in the existing single-loop control architecture. The LVDT sensor group includes at least one pair of LVDT sensors, which are respectively installed on different valves of the steam turbine, such as the main steam valve, high-pressure regulating valve, and medium-pressure regulating valve. The core function of these LVDT sensors is to accurately convert the mechanical displacement of the valve into corresponding electrical signals, providing basic data for subsequent control and monitoring. The control module is the core control and management part of the entire device, which integrates multiple independent control units, a joint control unit, a monitoring unit, as well as a data storage unit, a communication interface, and a redundant power supply module. Each LVDT sensor is connected to the corresponding control unit in the control module through a dedicated control cable. The control unit is responsible for performing targeted control and measurement operations on the connected LVDT sensors. The joint control unit coordinates and manages all control units and connected LVDT sensors in a unified manner to ensure that all parts can work together. The monitoring unit is connected to the joint control unit and receives and monitors the output signals and related operating parameters of each LVDT sensor in real time.

[0021] In some implementations, each LVDT sensor is configured redundantly, and the LVDT sensor includes: a primary measurement module for routine monitoring of valve position; and a backup measurement module, which the control unit automatically switches to when the primary measurement device malfunctions or the deviation exceeds a preset value. Figure 1 As shown, each LVDT sensor employs a redundant configuration, consisting of a main measurement module and a backup measurement module. The main measurement module, as the primary component for daily valve position monitoring, continuously acquires the valve's mechanical displacement and converts it into an electrical signal, transmitting it to the corresponding control unit. The backup measurement module remains in standby mode. When the control unit detects a malfunction in the main measurement module—such as output signal interruption or distortion—or if the measurement deviation between the main and backup modules exceeds a preset value (this preset value can be set according to the actual application scenario, but is generally recommended to be 3%-5% of the measurement range), the control unit will automatically and quickly switch to the backup measurement module to ensure the continuity and accuracy of valve position measurement.

[0022] In some embodiments, the monitoring unit is configured by the control unit with monitoring logic: based on real-time signal comparison, it continuously compares the output signals of the two LVDT sensors with a preset threshold. For example... Figure 1 As shown, the monitoring unit also has a signal trend analysis function. When the rate of change of five consecutive measurements exceeds a preset slope threshold, the monitoring unit will immediately trigger a pre-alarm state and automatically record the change curve. The change curve is recorded in a common binary format and stored in the data storage unit for easy subsequent querying and analysis. The setting of the preset slope threshold needs to take into account the normal operating speed of the valve and possible abnormal operating conditions to ensure that potential faults can be detected in a timely manner.

[0023] In some embodiments, it further includes: an alarm module, which is connected to the monitoring unit and is used to issue an alarm when the alarm module threshold is greater than a preset threshold. For example... Figure 1 As shown, the warning module is connected to the monitoring unit. When the monitoring unit detects that the measured value exceeds the preset threshold, the warning module will immediately sound an alarm. The alarm method combines audible and visual alarms. The audible alarm uses a high-decibel buzzer, and the visual alarm uses a red LED indicator. Based on the severity of exceeding the threshold, the alarm levels are divided into general alarms and emergency alarms. During a general alarm, the buzzer sounds intermittently, and the LED indicator flashes; during an emergency alarm, the buzzer sounds continuously, and the LED indicator remains constantly lit, allowing staff to quickly distinguish the urgency of the alarm and take appropriate action.

[0024] In some embodiments, the control cable is a shielded twisted-pair cable with the shield grounded at one end to suppress electromagnetic interference. The cable has an outer diameter of 6-8 mm and can withstand ambient temperatures from -40°C to 125°C. Figure 1 As shown, the control cable is a shielded twisted-pair cable with the shield grounded at one end. This design effectively suppresses electromagnetic interference because the turbine operating environment contains numerous electromagnetic devices that generate strong electromagnetic interference. Grounding the shield at one end directs the interference signals to the ground, preventing them from affecting the electrical signals transmitted within the cable. The cable's outer diameter is 6-8mm, ensuring sufficient mechanical strength while facilitating laying and installation in the complex environment of the turbine. Furthermore, the cable can withstand ambient temperatures from -40℃ to 125℃, fully adapting to the temperature variations during turbine operation and ensuring normal operation under various extreme temperature conditions.

[0025] In some implementations, the control module further includes a data storage unit and a communication interface. The data storage unit can store at least three months of measurement data, and the communication interface supports Modbus or Profibus protocols to enable data interaction with a host computer. Figure 1As shown, the data storage unit uses a high-performance storage chip, capable of storing at least three months of measurement data. This data includes the measured values ​​of each LVDT sensor, the sensor's operating status, alarm records, etc., providing detailed data support for subsequent system maintenance, fault analysis, and performance evaluation. The communication interface supports Modbus or Profibus protocols, enabling data interaction with a host computer. Data transmission uses full-duplex mode, and the transmission rate can be adjusted according to actual needs, up to a maximum of 1Mbps. Through the communication interface, the host computer can obtain the operating data of the measuring device in real time, and can also remotely set and modify the parameters of the measuring device.

[0026] In some implementations, the monitoring logic further includes a signal trend analysis function, which triggers a pre-alarm state and records the change curve when the rate of change of five consecutive measurements exceeds a preset slope threshold. For example... Figure 1 As shown, the monitoring unit also has a signal trend analysis function. When the rate of change of five consecutive measurements exceeds a preset slope threshold, the monitoring unit will immediately trigger a pre-alarm state and automatically record the change curve. The change curve is recorded in a common binary format and stored in the data storage unit for easy subsequent querying and analysis. The setting of the preset slope threshold needs to take into account the normal operating speed of the valve and possible abnormal operating conditions to ensure that potential faults can be detected in a timely manner.

[0027] In some embodiments, the LVDT sensor is fixed to the valve body by an adjustable bracket with an adjustment range of ±15mm to compensate for installation errors. The connection between the sensor and the valve employs a ball joint structure to accommodate slight valve sway. Figure 1 As shown, the LVDT sensor is fixed to the valve body via an adjustable bracket, which is commercially available. The bracket's adjustment range is ±15mm. This design effectively compensates for potential installation errors during installation, ensuring that the relative position between the LVDT sensor and the valve meets the measurement requirements. The connection between the LVDT sensor and the valve uses a ball joint structure. This structure can flexibly adapt to the slight wobble generated by the valve during operation, avoiding any impact on measurement accuracy due to wobble.

[0028] In some embodiments, the system further includes a redundant power supply module that provides dual independent power to the control module and the LVDT sensor. This module automatically switches to the backup power supply when the main power supply voltage fluctuates by more than ±10%, with a switching time of less than 5ms. Figure 1As shown, the redundant power supply module provides dual independent power supplies for the control module and LVDT sensor: one is the main power supply, and the other is a backup power supply. The main and backup power supplies use different power supply lines to ensure that the backup power supply can be put into use promptly in the event of a main power supply failure. When the main power supply voltage fluctuates by more than ±10%, the monitoring circuit inside the redundant power supply module will quickly detect this anomaly and automatically switch to the backup power supply within less than 5ms. The switching process employs seamless switching technology, which will not affect the normal operation of the measuring device and ensures the power supply stability and reliability of the entire system.

[0029] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above description is only a preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. An LVDT measuring device, characterized in that, include: At least one pair of LVDT sensors are installed on different valves to convert the acquired valve mechanical displacement into electrical signals; The control module controls and measures the LVDT sensors by setting different control units, and each LVDT sensor is connected to the control unit via a control cable; a joint control unit performs joint control of each LVDT sensor; the joint control unit is also connected to a monitoring unit.

2. The LVDT measuring device according to claim 1, characterized in that: Each LVDT sensor is configured redundantly, and the LVDT sensor includes: a main measurement module for daily monitoring of valve position; and a backup measurement module, which the control unit automatically switches to when the main measurement module malfunctions or the deviation exceeds a preset value.

3. The LVDT measuring device according to claim 1, characterized in that: The monitoring unit is configured with monitoring logic by the control unit: based on real-time signal comparison, it is used to continuously compare the output signals of the two LVDT sensors with a preset threshold.

4. The LVDT measuring device according to claim 1, characterized in that: It also includes an alarm module, which is connected to the monitoring unit and is used to trigger an alarm when the threshold of the alarm module is greater than a preset threshold.

5. The LVDT measuring device according to claim 1, characterized in that: The control cable is a shielded twisted-pair cable with a single-end grounded shield to suppress electromagnetic interference. The cable has an outer diameter of 6-8 mm and can withstand ambient temperatures from -40℃ to 125℃.

6. The LVDT measuring device according to claim 1, characterized in that: The control module also includes a data storage unit and a communication interface. The data storage unit can store at least 3 months of measurement data, and the communication interface supports Modbus or Profibus protocols to enable data interaction with the host computer.

7. The LVDT measuring device according to claim 3, characterized in that: The monitoring logic also includes a signal trend analysis function. When the rate of change of five consecutive measurements exceeds a preset slope threshold, a pre-alarm state is triggered and the change curve is recorded.

8. The LVDT measuring device according to claim 1, characterized in that: The LVDT sensor is fixed to the valve body by an adjustable bracket with an adjustment range of ±15mm to compensate for installation errors. The connection between the sensor and the valve adopts a ball joint structure to accommodate the slight deflection of the valve.

9. The LVDT measuring device according to claim 1, characterized in that: It also includes a redundant power supply module, which provides dual independent power supply for the control module and the LVDT sensor. When the main power supply voltage fluctuates by more than ±10%, it automatically switches to the backup power supply with a switching time of less than 5ms.

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