Thermal power generating unit steam turbine control valve double-LVDT feedback device

Abstract

The utility model provides a thermal power generating unit steam turbine control valve double-LVDT (linear variable differential transformer) feedback device, which comprises a fixedly arranged mounting frame and two LVDT displacement sensors, and the LVDT displacement sensors are provided with sensing rods (1.1); the front fixing sleeve plate is provided with two magnetic rings, the induction rod of each LVDT displacement sensor is inserted into the corresponding magnetic ring, and when the piston rod moves, the induction rods and the magnetic rings can move relatively. The system further comprises a DEH control system which can control and collect signals of the double LVDT feedback devices. According to the steam turbine control valve, the double LVDT feedback devices are adopted for displacement of the control valve, the two LVDT feedback detection devices are independently arranged, when any VP card, an LVDT displacement sensor and an external connecting wire are short-circuited or open-circuited, a redundant backup feedback line can be directly switched without interference, operation of a unit cannot be affected, and detection feedback reliability and equipment operation safety are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine detection, in particular to a double LVDT feedback device for a steam turbine governing valve of a thermal power unit. Background Art

[0002] At present, single LVDT feedback devices are adopted for steam turbine governing valves of domestic thermal power units. The reliability of the equipment is relatively low. When the feedback signal of a single steam turbine governing valve is abnormal, it directly affects the safe and stable operation of the unit, causes equipment damage, and even leads to accidents. Therefore, it is necessary to regularly check the position feedback sensor (LVDT) of the oil motor of the high (medium) pressure regulating valve of the steam turbine to timely detect problems such as loosening, deformation, wear, and misalignment of its connecting rod. Among them, Figure 1 is the existing single LVDT feedback device. In view of this, a double LVDT feedback device for a steam turbine governing valve of a thermal power unit is proposed. Summary of the Invention

[0003] The technical solution adopted by the utility model to solve its technical problems is as follows:

[0004] A double LVDT feedback device for a steam turbine governing valve of a thermal power unit is provided, which includes a fixedly arranged mounting frame, and further includes two LVDT displacement sensors and a rear fixing sleeve plate. The rear fixing sleeve plate extends towards the outer peripheral side of the mounting frame and is installed on the mounting frame. The two LVDT displacement sensors are respectively installed on the fixing sleeve plate. Among them, the LVDT displacement sensor is provided with an induction rod.

[0005] It further includes a front fixing sleeve plate which is fixed at the end of the piston rod. The front fixing sleeve plate extends towards the circumferential side of the piston rod. Two magnetic rings are arranged on the front fixing sleeve plate. The induction rod of each LVDT displacement sensor is respectively inserted into the corresponding magnetic ring, and when the piston rod moves, the induction rod can move relative to the magnetic ring.

[0006] It further includes a DEH control system, which sets two feedback I / O points and is respectively connected to each LVDT displacement sensor. A signal isolator is set for each LVDT displacement sensor, and each signal isolator is powered by an independent 24V power supply. It also includes a governing valve control card and an analog input card set for each LVDT displacement sensor, and both can enter the distributed control at the back end.

[0007] Preferably, the two LVDT displacement sensors are symmetrically arranged at both ends of the rear fixing sleeve plate.

[0008] Preferably, there are 8 signal isolators and 20 24V power supplies in the DEH control system, and it further includes 10 safety isolators.

[0009] The beneficial effects of the present utility model are as follows. The steam turbine governing valve of the present utility model adopts a dual LVDT feedback device for valve displacement. The two LVDT feedback detections are independently set. When any VP card, LVDT displacement sensor, or external wiring is short-circuited or open-circuited, it will directly and non-intrusively switch to the redundant backup feedback line, which will not affect the operation of the unit, improving the reliability of detection feedback and the safety of equipment operation. In addition, all LVDT measuring points, power supplies, isolators, signal wiring, and card channels are independent throughout the process, which also complies with the requirements of Article 9.2.2 of the "Twenty-five Key Requirements for Preventing Power Production Accidents" (2023 Edition) issued by the National Energy Administration. Description of the Drawings

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0011] Figure 1 It is a schematic structural diagram of a single LVDT feedback device for an existing steam turbine governing valve;

[0012] Figure 2 It is a front view structural diagram of a dual LVDT feedback device for a steam turbine governing valve in an embodiment of the present utility model;

[0013] Figure 3 It is a side view structural diagram of a dual LVDT feedback device for a steam turbine governing valve in an embodiment of the present utility model

[0014] Figure 4 It is a schematic diagram of an existing DEH control system;

[0015] Figure 5 It is a schematic diagram of a DEH control system in an embodiment of the present utility model;

[0016] In the figure: 1 - LVDT displacement sensor, 1.1 - induction rod, 2 - mounting bracket, 3 - rear fixed sleeve plate, 4 - front fixed sleeve plate, 5 - magnetic ring, a - piston rod. Specific Embodiments

[0017] The following further illustrates the above solutions with specific embodiments. It should be understood that these embodiments are used to illustrate the present utility model rather than limit the scope of the present utility model. The implementation conditions adopted in the embodiments can be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0018] In a specific embodiment, a double LVDT feedback device for a steam turbine governing valve of a thermal power unit is provided, which includes a fixedly arranged mounting frame 2. The mounting frame 2 is usually mounted on the outer shell of the steam turbine governing valve. In this example, the mounting frame 2 is of a cylindrical structure and is mounted around the piston rod a of the steam turbine governing valve.

[0019] To realize the application of the double LVDT feedback device for the steam turbine governing valve, this example includes two LVDT displacement sensors 1. Since the existing single-valve double LVDT feedback device can be directly mounted between the piston rod a and the mounting frame 2, but after the improvement in this example, to realize the installation of the double LVDT and the synchronous detection of the double LVDT, it further includes a rear fixing sleeve plate 3. The rear fixing sleeve plate 3 extends towards the outer peripheral side of the mounting frame 2. The rear fixing sleeve plate 3 is mounted on the mounting frame 2. The two LVDT displacement sensors are respectively mounted on the fixing sleeve plate 3. Preferably, the two LVDT displacement sensors 1 are symmetrically arranged at both ends of the rear fixing sleeve plate 3, which is convenient for installation and maintenance. In addition, an induction rod 1.1 is provided on the LVDT displacement sensor.

[0020] In addition, it further includes a front fixing sleeve plate 4. The front fixing sleeve plate 4 is fixed at the end of the piston rod a. Similarly, to be able to correspond to the rear fixing sleeve plate 3, the front fixing sleeve plate 4 extends towards the circumferential side of the piston rod a. It should be noted that if the front fixing sleeve plate 4 is to extend towards the outside of the piston rod a, in this example, a notch is provided at the side end of the mounting frame 2, and the front fixing sleeve plate 4 extends outwards through the notch, thus avoiding the problem of structural interference. In addition, two magnetic rings 5 are provided on the front fixing sleeve plate 4. The induction rod 1.1 of each LVDT displacement sensor 1 is respectively inserted into the corresponding magnetic ring 5, and when the piston rod a moves, the induction rod 1.1 can move relative to the magnetic ring 5 to generate an induced displacement signal.

[0021] In addition, to implement the above displacement signal detection, feedback, and acquisition, a DEH control system is also included. During the operation of the DEH control system, the boiler supplies high-temperature and high-pressure steam to the steam turbine generator through the high-pressure control valve, and supplies reheated steam to the steam turbine through the reheater and the intermediate-pressure control valve. The steam turbine controller outputs a flow command through logical calculation to adjust the steam flow, and then accurately and quickly adjusts the opening degrees of the high-pressure and intermediate-pressure control valves to control the steam turbine generator to output the set electrical load (i.e., the power generation). Each regulating valve is operated by a servo valve electro-hydraulic actuator. Depending on the selected mode, the steam turbine can operate through speed, load, or pressure control. The function of the high-pressure control valve position controller is to set the valve position value according to the operation mode of the steam turbine to ensure that the main steam flow can always meet the set requirements. The required valve position can be determined by the set value forming module in the main controller or directly by the valve position limit sub-module. The main applications are as follows: The larger the valve position setting, the more steam is allowed to enter the high-pressure cylinder, and the greater the output of the steam turbine. The actual displacement value of the electro-hydraulic actuator (EHA) can be obtained through the LVDT displacement sensor. The valve position controller of the control valve is implemented through an electro-hydraulic converter, and the valve position controller is a proportional adjustment. It controls the working coil of the servo valve through a voltage / current converter. To increase reliability, the two working coils are respectively controlled by separate voltage / current converters.

[0022] Specifically, in this example, the measurement and feedback of the signals of each LVDT displacement sensor 1 can be realized. Two feedback I / O points are set, which are respectively connected corresponding to each LVDT displacement sensor 1, and a signal isolator is set for each LVDT displacement sensor 1 to isolate the signal unidirectionally, strengthen the signal, and prevent signal attenuation. Each signal isolator is powered by an independent 24V power supply; a control card for the control valve corresponding to each LVDT displacement sensor 1 is also included, which is mainly used to receive commands and feedback, process signals, and quickly adjust and control. In addition, an analog input card is also included. The analog input card converts the electrical signal into an analog signal that can be recognized by the DCS, and the backend can all enter the distributed control to further process the feedback signal, enabling the feedback of the two LVDTs to be displayed on the DCS screen clearly, facilitating monitoring and abnormal handling. In addition, the feedback signals of the steam turbine control valves are all provided with historical records, which is convenient for cause analysis and processing.

[0023] Therefore, in this example, the detection, feedback, and acquisition of the steam turbine governing valve dual LVDT feedback device are independently set. When any VP card, LVDT displacement sensor, or external wiring experiences a short circuit or open circuit, it will directly and smoothly switch to the redundant backup feedback line without affecting the operation of the unit, thereby improving the reliability of detection and feedback. Additionally, all LVDT measurement points, power supplies, isolators, signal wiring, and card channels are fully independent throughout the process, which also complies with the requirements of Article 9.2.2 of the "Twenty-five Key Requirements for Preventing Power Production Accidents" (2023 Edition) issued by the National Energy Administration.

[0024] On this basis, before the transformation, a total of 4 signal isolators, 4 signal distributors, and 16 channels of 24V power supply were required for 1 unit; after the transformation, the number of signal isolators was preferably set to 8, 4 signal distributors were retained as original spares, the 24V power supply was set to 20 channels, and 10 safety isolators were also included. The power supply can supply power to the signal isolation device for the valve position feedback signal of the governing valve respectively, and the power distribution should ensure that the power supply for the dual LVDT displacement sensors installed complies with the principle of independent and decentralized power supply. Each feedback signal is sent to the corresponding redundant valve servo card in the DEH control cabinet through the signal isolation device respectively. The feedback signal of the dual-output displacement sensor realizes a one-card-one-signal redundant configuration. When any one of the VP cards, displacement sensors, or external wiring experiences a short circuit or open circuit, the control system will directly and smoothly switch to the redundant backup system.

[0025] Inspired by the ideal embodiments of the present invention described above, through the above description, relevant staff can completely make various changes and modifications within the scope without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A dual LVDT feedback device for a steam turbine valve regulating valve of a thermal power unit, comprising a fixed mounting frame (2), characterized in that: It also comprises two LVDT displacement sensors (1) and a rear fixed sleeve (3), wherein the rear fixed sleeve (3) extends toward the outer peripheral side of the mounting frame (2), the rear fixed sleeve (3) is mounted on the mounting frame (2), and the two LVDT displacement sensors are respectively mounted on the fixed sleeve (3), wherein the LVDT displacement sensor is provided with a sensing rod (1.1); It also comprises a front fixed sleeve (4), the front fixed sleeve (4) being fixed to the end of the piston rod (a), the front fixed sleeve (4) extending toward the circumference of the piston rod (a), two magnetic rings (5) being arranged on the front fixed sleeve (4), the sensing rod (1.1) of each LVDT displacement sensor (1) being respectively inserted into the corresponding magnetic ring (5), and when the piston rod (a) moves, the sensing rod (1.1) and the magnetic ring (5) can move relative to each other; It also includes a DEH control system, which is provided with two feedback I / O points, which are respectively connected to each of the LVDT displacement sensors (1), and a signal isolator is provided for each of the LVDT displacement sensors (1), and each signal isolator is powered by an independent 24V power supply; it also includes a valve control card and an analog input card component provided for each of the LVDT displacement sensors (1), and the back end can all enter decentralized control.

2. A dual LVDT feedback device for regulating valve of a steam turbine of a thermal power unit as claimed in claim 1, characterized in that: The two LVDT displacement sensors (1) are symmetrically arranged at two ends of the rear fixed sleeve plate (3).

3. A dual LVDT feedback device for regulating valve of a steam turbine of a thermal power unit as claimed in claim 1, characterized in that: The DEH control system has 8 signal isolators, 20 24V power supplies, and 10 safety isolation barriers.

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