A contact force compensation system and method for a transformer on-load tap changer

Abstract

A contact pressure compensation system and method of on-load tap changer of transformer, comprising: an integrated sensing contact unit arranged at a high-voltage side of the transformer, configured to collect original pressure data P and real-time temperature data T in a closed state of the contact 原始 ; and an adaptive actuator arranged at a low-voltage side of the transformer, comprising a driving mechanism and a spring pre-tightening force adjusting device mechanically coupled to the fast-acting mechanism. The application monitors the contact pressure as a monitorable parameter on-line through the integrated sensing contact unit, and actively compensates the pressure decay through the adaptive actuator, so as to ensure that the contact of the on-load tap changer maintains the designed contact pressure in the whole life cycle, suppresses the overheating, bouncing and arc problems caused by insufficient pressure, prolongs the actual service life of the contact and the switch body, and reduces the risk of sudden failure.

Description

Technical Field

[0001] This invention relates to the field of voltage regulating transformer equipment technology, and more specifically to a contact pressure compensation system and method for an on-load tap changer of a transformer. Background Technology

[0002] On-load tap changers are the core components of power transformers for load voltage regulation, mainly composed of switching switches, tap selectors, quick-action mechanisms, and drive mechanisms. The contact pressure between the moving and stationary contacts of the switch is a key parameter determining its electrothermal performance and mechanical lifespan. The parameters of existing switch drive mechanisms are set based on the mechanical characteristics of the contacts in their brand-new state at the factory. During long-term operation, various components of the drive mechanism undergo irreversible physical degradation. The contact surface thins due to mechanical wear and arc erosion. The preload springs, constantly immersed in high-temperature transformer oil, experience stress relaxation. This leads to a continuous decrease in the actual contact pressure between the contacts as the on-load tap changer's service life extends. Existing drive mechanisms cannot detect this pressure decay and continue switching with a fixed initial torque and spring force. This causes localized overheating in the later stages of operation due to contact pressure decay, and even during transient switching, insufficient preload can exacerbate contact bounce, inducing severe arc erosion and mechanical jamming. Summary of the Invention

[0003] To address the technical problems existing in existing on-load tap changers, the first aspect of this invention proposes a contact pressure compensation system for an on-load tap changer of a transformer, comprising: An integrated sensing contact unit is installed on the high-voltage side of the transformer to collect raw pressure data P when the contacts are closed. 原始 and real-time temperature data T; An adaptive actuator, located on the low-voltage side of the transformer, includes a drive mechanism and a spring preload adjustment device mechanically coupled to a rapid-action mechanism. The signal transmission subsystem, bridging the high-pressure and low-pressure sides, is used to transmit the raw pressure data P collected by the integrated sensing contact unit. 原始 Real-time temperature data T is transmitted to the low-pressure side; The controller is located on the low-voltage side of the transformer. Its signal input terminal is communicatively connected to the output terminal of the signal transmission subsystem, and its control output terminal is electrically connected to the spring preload adjustment device and the drive mechanism, respectively. The integrated sensing contact unit includes a contact body, an elastic support base that supports the contact body and provides initial contact pressure, and a thin-film pressure sensor and a temperature sensor disposed inside the elastic support base. The thin-film pressure sensor is used to collect raw pressure data P reflecting the magnitude of the contact pressure in real time when the contact is closed. 原始The temperature sensor is used to synchronously collect real-time temperature data T, which characterizes the working environment temperature of the contact body. The controller is configured to correct the original pressure data based on temperature data and compare the corrected pressure with a preset reference value to generate control commands to drive the spring preload adjustment device to actively adjust the pre-compression length L of the spring in the rapid action mechanism.

[0004] Preferably, the pressure sensor is a thin-film pressure sensor, and its exterior is covered with an electromagnetic shielding layer made of permalloy material to suppress high-frequency electromagnetic interference during switching transients.

[0005] Preferably, the temperature sensor is a PT1000 platinum resistance temperature sensor, which is placed near the pressure sensor so that the collected real-time temperature data T can accurately reflect the actual temperature state of the pressure sensor.

[0006] Preferably, the signal transmission subsystem uses optical fiber communication to achieve signal transmission and electrical isolation; The signal transmission subsystem includes: A signal conditioning and electro-optical conversion unit is installed on the high-voltage side; A photoelectric conversion unit located on the low-voltage side; Insulated optical fiber connecting the signal conditioning and electro-optical conversion unit and the photoelectric conversion unit.

[0007] Preferably, the spring preload adjustment device includes a micro stepper motor and a precision lead screw and nut pair. The control end of the micro stepper motor is electrically connected to the controller. The micro stepper motor drives the precision lead screw and nut pair to rotate, causing the pressure plate to be linearly displaced along the axial direction of the rapid action mechanism, thereby precisely adjusting the spring preload length L of the rapid action mechanism.

[0008] As a second aspect of the present invention, a method for compensating the contact pressure of an on-load tap changer for a transformer is provided, based on the above-mentioned on-load tap changer contact pressure compensation system, comprising the following steps: S1: Initial self-calibration steps: Before the system is put into operation for the first time or at a preset maintenance node, the controller controls the on-load tap changer to perform a full tap range cycle operation under no-load conditions. During this process, the initial static pressure value corresponding to each tap position when it is in steady-state closure is collected and recorded, and this value is calibrated as the static pressure reference value P0 for each tap position. The mapping relationship between tap position and static pressure reference is constructed and stored. S2: Static Perception and Pre-Decision Steps: When the controller receives an external gear shifting command, before performing any substantial mechanical switching action, the following sub-steps are forcibly inserted: S21: Obtain and read the raw pressure data P at the current tap position. 原始The system uses real-time temperature data T and calls a preset temperature compensation function to adjust the original pressure data P. 原始 The calculation process is performed to eliminate the effects of temperature drift, resulting in the corrected static pressure value P. 校正 ; S22: Retrieve the static pressure reference value P0 corresponding to the current tap position, and set the corrected static pressure value P 校正 The value is compared with the static pressure reference value P0, and the following zoning decision logic is executed based on the comparison result: If P 校正 If ≥85% P0, it is determined to be a normal state, and the preset standard action parameters of the main drive motor (31) and the rapid action mechanism (34) are maintained, allowing the switching action to continue to be executed; If 60%P0≤P 校正 If the value is less than 85%P0, it is determined to be in a compensation state. The compensation amount ΔL of the spring pre-compression length required to restore the contact pressure to the target level is calculated, and a first control command is generated to drive the spring preload adjustment device to perform the compensation operation. At the same time, a second control command is generated to modify the action characteristic curve of the main drive motor and increase its initial output torque. If P 校正 If the value is less than 60% of P0, it is considered a dangerous situation. The execution of this file transfer instruction will be immediately blocked, and a high-priority alarm signal will be generated. If P 校正 If the value is greater than 110%P0, it is considered an abnormal state, and a warning signal is generated to prompt for inspection or oil flushing operation. S3: Dynamic Waveform Acquisition Step: During the transient process when the adaptive actuator is allowed to perform tap-switching, the controller continuously records the dynamic pressure fluctuation data output by the thin-film pressure sensor at a sampling frequency of not less than 10kHz, forming a time-domain dynamic pressure characteristic waveform that characterizes the mechanical characteristics of this switching action. By analyzing this waveform, at least the peak value of the switching impact pressure P is extracted. 峰值 Dynamic characteristic parameters including contact bounce count N and bounce amplitude, and the settling time T required for the contact to go from bounce to stable closure; S4: Health assessment and life prediction steps: The controller at least comprehensively utilizes the dynamic characteristic parameters extracted from step S3, the working current monitoring value during this switching process, and the contact pressure attenuation change rate obtained from historical data. It uses the Kalman filter algorithm to make the optimal state estimate of the remaining effective thickness of the contact, which reflects the degree of contact wear, and generates and outputs a quantitative assessment index characterizing the current health level of the contact based on the estimation results.

[0009] Preferably, in step S22, the spring pre-compression length compensation amount ΔL is calculated and determined according to the following formula: ΔL=k·(P0-P校正 ); Where k is the system equivalent elastic coefficient associated with the stiffness coefficient of the rapid action mechanism and the elastic modulus of the elastic support, which is a constant obtained through prior experimental calibration.

[0010] Preferably, in step S22, the operation of generating a second control command to modify the operating characteristic curve of the main drive motor and increase its initial output torque specifically includes: The controller outputs a modulated pulse width modulation signal to the servo driver of the main drive motor. By adjusting the duty cycle of the pulse width modulation signal, the operating current of the main drive motor at the beginning of the switching action is temporarily increased, thereby increasing its output torque to overcome the increase in mechanical resistance torque caused by the increase in preload of the rapid action mechanism after the spring preload adjustment device performs compensation operation.

[0011] Preferably, the quantitative assessment indicators representing the current health level of the contact generated in step S4 include at least one or more of the following: the percentage of remaining contact health and the estimated number of safe remaining operations.

[0012] Preferably, the method further includes step S5: The quantitative evaluation indicators generated in step S4 are modeled and encapsulated according to the IEC 61850 communication protocol standard, and the encapsulated data is uploaded to a remote operation and maintenance monitoring platform through a network communication interface to realize the visualization of status display and early warning management on the platform.

[0013] Compared with the prior art, the advantages of the present invention are as follows: This application integrates a sensing contact unit to monitor contact pressure online as a measurable parameter, and actively compensates for pressure attenuation through an adaptive actuator. This ensures that the contact maintains the design-required contact pressure throughout its entire life cycle, suppressing overheating, bouncing, and arcing problems caused by insufficient pressure. This extends the actual service life of the contact and switch body, thereby reducing the risk of sudden failures.

[0014] Furthermore, by acquiring and analyzing dynamic pressure waveforms, the wear status of contacts can be quantitatively assessed and remaining lifespan predicted, laying the foundation for intelligent operation and maintenance of transformers and power grids, thereby reducing operation and maintenance costs and improving the management level of power grid assets. In addition, the waveform can identify abnormally high pressure and issue corresponding warnings, improving the system's early identification and response capabilities to potential faults such as foreign object obstruction. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall architecture and signal flow of the on-load tap changer contact pressure compensation system of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of a moving contact assembly in the prior art.

[0017] Figure 3 This is a schematic diagram of the integrated sensing contact unit of the present invention.

[0018] Figure 4 This is a schematic diagram showing the relationship between the low-pressure operating mechanism and the high-pressure side mechanical transmission in existing technology.

[0019] Figure 5 This is a schematic diagram illustrating the structural principle of the spring preload adjustment device in the adaptive actuator of this invention.

[0020] Figure 6 This is a block diagram illustrating the principle of high- and low-voltage electrical isolation transmission in the signal transmission subsystem of this invention.

[0021] Figure 7 This is a logic flowchart of the contact pressure compensation method for the on-load tap changer of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 100, Transformer; 100a, High-voltage side; 100b, Low-voltage side; 200, Low-voltage operating mechanism box; 10, On-load tap changer; 11, Changeover switch; 11a, Moving contact assembly; 111, Contact body; 112, Flexible support; 113, Conductive connector; 114, Moving contact bracket; 11b, Stationary contact assembly; 11c, Transition resistor; 12, Tap selector; 20, Integrated sensing contact unit; 21, Contact body; 22, Flexible support; 221, Load surface; 222, Wall material; 23. 24. Thin-film pressure sensor; 25. Temperature sensor; 26. Electromagnetic shielding layer; 251. Permalloy structural layer; 30. Adaptive actuator; 31. Main drive motor; 32. Reduction gear set; 33. Drive shaft; 34. Quick action mechanism; 341. Spring; 35. Spring preload adjustment device; 351. Miniature stepper motor; 352. Precision lead screw and nut pair; 353. Pressure plate; 40. Controller; 50. Signal transmission subsystem; 51. First converter; 52. Second converter; 53. Insulated optical fiber; 54. Third converter. Detailed Implementation

[0023] To better illustrate the technical content of the present invention, specific embodiments are provided below in conjunction with the accompanying drawings. Example

[0024] This embodiment provides a contact pressure compensation and health status sensing system for an on-load tap changer of a transformer, which mainly includes an on-load tap changer 10, an integrated sensing contact unit 20, an adaptive actuator 30, a signal transmission subsystem 50, and a controller 40.

[0025] Combination Figure 1 As shown, the on-load tap changer 10 is typically installed inside the oil tank of the transformer 100. The core functional components of the on-load tap changer 10 are divided into two main parts: the tap selector 12 and the switching switch 11. The switching switch 11 is located on the high-voltage side 100a of the transformer 100, and its potential is connected to the transformer windings. It operates in a harsh environment of high voltage and strong oil flow. The main function of the switching switch 11 is to quickly switch the taps under load conditions. The switching switch 11 mainly includes a moving contact assembly 11a, a stationary contact assembly 11b, and a transition resistor 11c.

[0026] Among them, the moving contact assembly 11a is the direct actuator in the switching switch 11 that performs the current conduction and interruption.

[0027] Combination Figure 2 As shown, in a typical structure, the moving contact assembly 11a consists of multiple contact units connected in parallel. Each contact unit includes a contact body 111, an elastic support base 112, and a corresponding conductive connector 113.

[0028] One end of the conductive connector 113 is fixedly connected to the contact body 111, and the other end is electrically connected to the lead-out conductive rod or transition resistance circuit of the switching switch 11 through a flexible connection structure, thereby drawing out the load current on the contact body 111.

[0029] The elastic support seat 112 typically uses a disc spring assembly or a helical spring. One end of the spring is fixed to the moving contact bracket 114, and the other end supports the contact body 111, providing a preload force to the contact body 111 in the direction of the stationary contact.

[0030] When the moving and stationary contacts are closed, the compression deformation of the elastic support 112 generates contact pressure, ensuring low contact resistance and good electrical contact stability.

[0031] Furthermore, during the switching action, the kinetic energy released by the spring of the quick action mechanism 35 is transmitted to the moving contact support 114 through the transmission shaft system, driving the entire moving contact assembly to rotate or move linearly around the main shaft, thereby completing the separation and engagement with different stationary contacts.

[0032] However, as mentioned above, this traditional moving contact assembly only has a single mechanical support function and cannot sense and respond to real-time changes in contact pressure.

[0033] Combination Figure 3 As shown, the present invention proposes an integrated sensing contact unit 20, which is installed on the moving contact bracket 114 of the switching switch, directly replacing the original contact assembly, and while retaining the original conductivity and contact pressure, it also integrates state sensing capability.

[0034] Specifically, the contact body 21 is the core component for conducting current. The material can be copper-tungsten alloy or copper-chromium alloy, which has excellent resistance to arc erosion. The contact body 21 is in close contact with the load surface 221 of the elastic support 22.

[0035] Optionally, the elastic support 22 can be a disc spring assembly, a helical spring, or a rubber elastomer, etc., which provides an upward preload to the contact body 21 to ensure reliable pressing with the upper stationary contact.

[0036] Furthermore, a pressure sensor 23, specifically a thin-film pressure sensor, is embedded within the internal cavity or force path of the elastic support 22. Since the thin-film pressure sensor 23 is in close contact with the force-bearing surface of the elastic support 22, it can directly sense and output an electrical signal P proportional to the contact pressure. 原始 .

[0037] Furthermore, to protect the thin-film pressure sensor 23 from high-frequency electromagnetic field interference generated by the switching arc, a permalloy structural layer 251 is wrapped around its exterior. Thus, an electromagnetic shielding layer 25 is formed on the outside of the thin-film pressure sensor 23.

[0038] Furthermore, a temperature sensor 24 is installed adjacent to the diaphragm pressure sensor 23 to synchronously collect ambient oil temperature, providing a basis for temperature compensation of subsequent pressure data. Specifically, a PT1000 platinum resistance temperature sensor can be selected.

[0039] The elastic support 22 has a self-sealing wire hole on its wall material 222 for leading out the signal lines of the pressure sensor 23 and the temperature sensor 24. The wire hole is vacuum sealed with a sealant that is resistant to high temperature transformer oil corrosion, which ensures signal output without affecting the mechanical properties and sealing performance of the elastic support 22.

[0040] Thus, through the above structural improvements, the integrated sensing contact unit 20 embeds contact pressure and temperature sensing functions without changing the original contact shape and interface, enabling the contact of the switching switch to have the ability to directly sense pressure and temperature online.

[0041] Furthermore, the operating energy of the on-load tap changer 10 originates from the low-voltage operating mechanism box 200 located outside the oil tank of the transformer 100.

[0042] In existing technologies, combined Figure 4 As shown, the low-voltage operating mechanism housing 200 houses the main drive motor 31, the reduction gear set 32, and the drive shaft 33. The quick-action mechanism 34 is located inside the transformer 100.

[0043] Specifically, the main drive motor 31 is typically a three-phase asynchronous motor or a servo motor, and its output shaft is connected to the input shaft of the reduction gear set via a coupling. The function of the reduction gear set 32 ​​is to convert the high-speed rotational motion of the motor into a low-speed, high-torque output to meet the timing requirements of the tap selector 12 and the switching switch 11. The output shaft of the reduction gear set 33 is connected to the quick-action mechanism 34 located inside the oil tank via a vertical or horizontal drive shaft 33.

[0044] The quick-action mechanism 34 is the key device for the quick switching of the switch 11.

[0045] Specifically, upon receiving the gear shift command, the main drive motor 31 starts, driving the energy storage cam or crank arm of the quick-action mechanism 34 to rotate via the reduction gear set 32 ​​and drive shaft 33, thereby compressing and storing energy in the quick-action element. When the stored energy reaches the designed dead point position, the spring is released instantaneously, and its stored elastic potential energy is converted into enormous kinetic energy, driving the moving contact assembly 11a of the switch 11 to complete the switching from one tap position to another at an extremely high speed (typically within tens of milliseconds). After the switching is completed, the contact closes in the new position, and the contact pressure is maintained by the elastic support 22 and the residual preload of the quick-action mechanism 34.

[0046] However, the driving parameters of this traditional operating mechanism are fixed, especially the pre-compression of the spring, which is set at the factory and cannot be adjusted according to the wear of the contacts.

[0047] Therefore, the adaptive actuator 30 includes a drive mechanism and a spring preload adjustment device 35 mechanically coupled to the rapid action mechanism 34; the drive mechanism includes a conventional main drive motor 31, a reduction gear set 32, and a drive shaft 33. The spring preload adjustment device 35 is located at the rear end of the rapid action mechanism 34 (i.e., the end away from the energy storage cam).

[0048] Combination Figure 6 As shown, the spring preload adjustment device 35 includes a micro stepper motor 351 and a precision lead screw and nut mechanism 352. The micro stepper motor 351 is fixedly mounted on the bracket of the operating mechanism box, and its control end is connected to the controller 40 via a signal line. The output shaft of the stepper motor 351 is coaxially connected to the screw of the precision lead screw via a coupling. A nut is screwed onto the lead screw, and the nut is fixedly connected to a pressure plate 353 that abuts against the rear end of the rapid action mechanism 34.

[0049] Specifically, when the controller 40 determines that contact pressure compensation is needed based on the sensing data, it sends a pulse command to the micro stepper motor 351. The stepper motor 351 rotates at a precise angle according to the command, driving the lead screw to rotate via the coupling. Since the nut is restricted from rotating, the rotational motion of the lead screw is converted into a precise linear displacement of the nut and the pressure plate 353 fixed to it along the axial direction of the lead screw.

[0050] Thus, the movement of the pressure plate 353 directly changes the pre-compression length L of the spring 341 of the rapid action mechanism 34, thereby achieving quantitative and reversible adjustment of the spring preload. This adjustment process is completed in the stationary state of the switch and will not cause any interference to the ongoing switching action.

[0051] As mentioned above, the spring preload adjustment device 35 and the controller 40 form a closed-loop control system to achieve adaptive compensation of contact pressure based on real-time sensing data. When pressure decay is sensed, the system can actively adjust the preload of the spring 341 of the fast action mechanism 34 in the stationary state of the switch, thereby maintaining the stability of the contact pressure.

[0052] Furthermore, the signal transmission subsystem 50 is connected between the high-voltage side 100a and the low-voltage side 100b, and can optionally employ an optical fiber transmission scheme. The signal transmission subsystem 50 includes: a signal conditioning and electro-optical conversion unit disposed on the high-voltage side 100a; a photoelectric conversion unit disposed on the low-voltage side 100b; and an insulated optical fiber 53 connecting the two.

[0053] The signal conditioning and electro-optical conversion unit includes a first converter 51 and a second converter 52, and the photoelectric conversion unit includes a third converter 53.

[0054] Specifically, in combination Figure 6 As shown, on the high-pressure side 100a, the weak analog signals from the thin-film pressure sensor 23 and the temperature sensor 24 are first converted into digital signals by the first converter 51 (e.g., a low-power signal conditioning and A / D converter), and then drive the second converter 52 (e.g., an electro-optical converter, optionally a laser diode) to convert the electrical pulses into optical pulses.

[0055] Furthermore, the optical pulses are transmitted through a high-insulation-strength insulated optical fiber 53 to the low-voltage side 100b, which is at ground potential. On the low-voltage side 100b, a third converter 54 (e.g., a photoelectric converter, optionally such as a photodiode) recovers the received optical pulses into electrical signals and transmits them to the controller 40.

[0056] Thus, by adopting a fiber optic transmission scheme and setting up an electromagnetic shielding layer, the problem of reliable transmission of high-voltage side sensing signals in a strong electromagnetic interference environment is solved, ensuring the accuracy of sensing data and the long-term operational stability of the system, as well as ensuring the safety of personnel and equipment.

[0057] Furthermore, the controller 40 is the core control and processing unit of the entire system, and can be selected as an embedded industrial control device based on a high-performance microprocessor or digital signal processor.

[0058] Specifically, the controller 40 receives digital signals from the signal transmission subsystem 50 through a data interface and has internally embedded temperature compensation algorithm, pressure zoning judgment logic, motor control algorithm, and life prediction model based on Kalman filtering.

[0059] The output of the controller 40 is electrically connected to the stepper motor 351 of the spring preload adjustment device 35 and the servo driver of the main drive motor 31, respectively, to send corresponding control commands.

[0060] Specifically, controller 40 is configured as follows: Obtain the pre-calibrated static pressure reference value P0 corresponding to the current tap position; Call the preset temperature compensation function to apply the original pressure data P 原始 The calculation process is performed to eliminate the effects of temperature drift, resulting in the corrected static pressure value P. 校正 ; The corrected static pressure value P 校正 The value is compared with the static pressure reference value P0, and a control command is generated based on the comparison result to drive the spring preload adjustment device 35 to actively adjust the pre-compression length L of the spring 341 in the quick action mechanism 34. Example

[0061] Combination Figure 7 As shown, the second aspect of the present invention proposes a method for contact pressure compensation and health status sensing of an on-load tap changer, which utilizes the above-mentioned on-load tap changer contact pressure compensation and health status sensing system, and includes the following steps: Step S1: Initialization and self-calibration.

[0062] After the system is powered on for the first time or after maintenance is completed, the operator can trigger the self-calibration command through the human-machine interface.

[0063] The controller 40 controls the main drive motor 31 to run in low speed mode, driving the transmission mechanism of the on-load tap changer. The transmission mechanism drives the tap selector 12 to perform a full-stroke operation cycle that traverses all voltage regulation levels (e.g., from level 1 to level N, and then back to level 1) under no-load conditions.

[0064] During this cycle, whenever the tap selector 12 completes the selection action of moving from one voltage regulation position to an adjacent voltage regulation position, the continued movement of the transmission mechanism will trigger the energy storage mechanism of the switching switch to release energy, thereby forcing the switching switch 11 to perform a rapid switching action in accordance with it. Since this full-stroke operation cycle is carried out under no-load conditions, the contacts of the switching switch 11 are in a state of following the non-switching load current during the rapid switching action, and return to the closed stationary state after the action is completed.

[0065] At the moment when the switching contact of each voltage level is stationary and closed, the controller 40 collects the static pressure data P reported by the integrated sensing contact unit 20 after a settling time through the signal transmission subsystem 50. 原始 And real-time temperature data T.

[0066] For each tap position, record its corresponding P. 原始 This value is then defined as the static pressure reference value P0 for that location. Finally, the reference values ​​for all locations form a mapping matrix of tap position - static pressure reference, which is stored in non-volatile memory.

[0067] Step S2: Static perception and decision-making.

[0068] When the controller 40 receives a gear shifting command (e.g., shifting from gear 3 to gear 4) from the transformer control system, the core intelligent decision-making process of this method is activated.

[0069] Sub-step S21: Data fusion and correction.

[0070] The controller 40 first reads the real-time static pressure P uploaded by the integrated sensing contact unit 20 at the current transformer operating voltage level (e.g., level 3). 原始 And the real-time temperature data T. Then, the built-in temperature compensation model is called, which uses a linear compensation function, the specific form of which is: P 校正 =P 原始 ×[1+α×(TT ref )] Among them, P 校正 To correct the static pressure value, P 原始 The raw pressure data is given, α is the temperature coefficient of the thin-film pressure sensor 23, and T is the real-time temperature data. ref The reference temperature is 25°C. The value of α is determined in advance through offline calibration experiments and stored in the controller 40.

[0071] Sub-step S22: Pressure zone judgment and decision.

[0072] The controller 40 first reads the reference pressure P0 corresponding to the current transformer operating voltage level (e.g., level 3), uploaded by the integrated sensing contact unit 20, and then sets P... 校正 In comparison.

[0073] Scenario 1: Normal state.

[0074] If P 校正 = 92% P0, which satisfies the condition ≥85% P0 (condition 1).

[0075] The system determines that the contact condition is good and no intervention is required. The controller 40 drives the main drive motor 31 to select the tap position and drives the rapid action mechanism 34 to store and release energy according to the preset standard program, thus successfully completing the switching.

[0076] Scenario 2: Compensation state.

[0077] If P 校正 =72% P0, falling within the interval [60%P0, 85%P0) (Condition 2).

[0078] The system determines that the contacts are worn or the spring is loose, requiring compensation. Controller 40 first calculates the spring pre-compression length compensation ΔL = k·(P0-P 校正 ).

[0079] The system's equivalent elastic coefficient k is predetermined using the following offline calibration method: Before the system is assembled but not yet put into operation, the pre-compression length of the spring 341 is quantitatively changed by the spring preload adjustment device 35, and the resulting change in static pressure value is recorded. Linear regression is performed on the acquired data, and the slope of the regression line is the k value. This k value is also stored in the non-volatile memory of the controller 40.

[0080] Then, a command containing a displacement of ΔL is immediately sent to the stepper motor 351 of the spring preload adjustment device 35, driving the spring pressure plate 353 forward to increase the preload. Simultaneously, a modified PWM control signal is sent to the driver of the main drive motor 31, causing it to provide, for example, 15% higher torque than the standard value during the initial switching phase to overcome the increased mechanical resistance. After compensation is completed, the switching action is then performed.

[0081] Scenario 3: Dangerous situation.

[0082] If P 校正 =45%P0, less than 60%P0 (Condition 3).

[0083] The system determines that the contacts are severely worn to the point of endangering safe operation. Controller 40 immediately locks out this gear adjustment operation, refusing to execute any subsequent mechanical actions, and sends a critical alarm message to the control room via the communication interface, awaiting manual intervention.

[0084] Scenario 4: Foreign object / early warning state.

[0085] If P 校正 = 125% P0, greater than 110% P0 (condition 4). The system determines that there may be foreign objects entering the contact gap or the mechanism is stuck.

[0086] Controller 40 will not lock out operations, but it will generate a warning message to alert maintenance personnel.

[0087] Step S3: Dynamic motion and waveform acquisition.

[0088] At the instant the switching action actually occurs (within approximately tens of milliseconds), the controller 40 continuously samples the output of the thin-film pressure sensor 23 at a high sampling rate, for example, 20 kHz, and records a pressure-time curve containing violent fluctuations. This curve is the dynamic pressure characteristic waveform of this switching action.

[0089] The waveform clearly reflects the impact force when the moving contact strikes the stationary contact, the possible multiple bounces, and the final stable crimping process. The controller performs online analysis on this waveform and extracts the peak impact pressure P. 峰值 Contact bounce count N and closing settling time T 稳定 The characteristic values ​​are compared with the data in the historical waveform library.

[0090] Specifically, the determination rule for the contact bounce count value N is as follows: the controller 40 continuously monitors and corrects the static pressure value P. 校正 When P 校正 If the value drops from a value greater than zero to zero and remains there for a preset timeout period (e.g., 2 milliseconds), and then rises back to a value greater than zero, it is considered that a bounce has occurred. The bounce count value N is obtained by counting the number of times this rule is satisfied during the entire action.

[0091] The controller 40 compares the extracted feature values ​​with the data in the historical waveform library.

[0092] Step S4: Life Prediction and Assessment.

[0093] The controller 40 comprehensively utilizes multi-source information for life assessment. First, it obtains the interruption current amplitude during this switching process from the current transformer. Then, combining the dynamic features extracted in step S3 and the pressure attenuation trend determined in step S2, it runs a state estimation algorithm based on Kalman filtering.

[0094] The algorithm's state variable is the remaining effective thickness of the contact, while the observed variables include contact pressure and bouncing characteristics during switching. The algorithm can recursively estimate the optimal remaining thickness value from noisy observation data.

[0095] Finally, the controller 40 converts the remaining thickness into user-friendly metrics, such as contact health percentage and estimated remaining number of operations. This information, along with other status data, is used to generate corresponding logical nodes and data objects according to the IEC 61850 standard, and uploaded to the station control layer network via the manufacturing message specification service. Maintenance personnel can then visually view the health status of each tap changer on the monitoring backend.

[0096] As mentioned above, this application sets up an initialization self-calibration step and a static perception pre-decision step, and forces the execution of partition judgment logic based on real-time perception data before each switching action. This enables the identification of various operating conditions such as normal state, compensation state, dangerous state and warning state before the switching action occurs, and adopts differentiated response strategies such as maintenance, compensation, blocking or warning according to different operating conditions, thereby improving the active safety protection capability of switch operation.

[0097] Furthermore, in addition to monitoring static contact pressure, the system also captures dynamic pressure characteristic waveforms of the switching transient process at a high sampling rate. By extracting and analyzing dynamic characteristic parameters such as impact peak value, number of bounces, and stabilization time from these waveforms, the system can gain a more comprehensive understanding of the degradation process of the contact's dynamic behavior, thereby achieving dynamic process diagnosis.

Claims

1. A contact pressure compensation system for an on-load tap changer of a transformer, characterized in that, include: An integrated sensing contact unit (20) is installed on the high-voltage side (100a) of the transformer (100) to collect raw pressure data P when the contacts are closed. 原始 and real-time temperature data T; An adaptive actuator (30) is located on the low-voltage side (100b) of the transformer (100) and includes a drive mechanism and a spring preload adjustment device (35) mechanically coupled to the quick-action mechanism (34). The signal transmission subsystem (50), connected between the high-pressure side (100a) and the low-pressure side (100b), is used to transmit the raw pressure data P collected by the integrated sensing contact unit (20). 原始 Real-time temperature data T is transmitted to the low-pressure side; The controller (40) is located on the low-voltage side (100b) of the transformer (100). Its signal input terminal is communicatively connected to the output terminal of the signal transmission subsystem (50), and its control output terminal is electrically connected to the spring preload adjustment device (35) and the drive mechanism, respectively. The integrated sensing contact unit (20) includes a contact body (21), an elastic support base (22) that supports the contact body (21) and provides initial contact pressure, and a thin-film pressure sensor (23) and a temperature sensor (24) disposed inside the elastic support base (22). The thin-film pressure sensor (23) is used to collect raw pressure data P reflecting the magnitude of the contact pressure in real time when the contact is closed. 原始 Temperature sensor (24) is used to synchronously collect real-time temperature data T that characterizes the working environment temperature of the contact body (21); The controller (40) is configured to correct the original pressure data based on the temperature data and compare the corrected pressure with a preset reference value to generate a control command to drive the spring preload adjustment device (35) to actively adjust the pre-compression length L of the spring (341) in the quick action mechanism (34).

2. The contact pressure compensation system for an on-load tap changer of a transformer according to claim 1, characterized in that, The pressure sensor (23) is a thin-film pressure sensor, and its exterior is covered with an electromagnetic shielding layer (25) made of permalloy material to suppress high-frequency electromagnetic interference during switching transients.

3. The contact pressure compensation system for an on-load tap changer of a transformer according to claim 1, characterized in that, The temperature sensor (24) is a PT1000 platinum resistance temperature sensor, which is placed adjacent to the pressure sensor (23).

4. The contact pressure compensation system for an on-load tap changer of a transformer according to claim 1, characterized in that, The signal transmission subsystem (50) uses optical fiber communication to achieve signal transmission and electrical isolation; The signal transmission subsystem (50) includes: A signal conditioning and electro-optical conversion unit is installed on the high-voltage side; A photoelectric conversion unit located on the low-voltage side; Insulated optical fiber (53) connecting the signal conditioning and electro-optical conversion unit and the photoelectric conversion unit.

5. The contact pressure compensation system for an on-load tap changer of a transformer according to claim 1, characterized in that, The spring preload adjustment device (35) includes a micro stepper motor (351) and a precision lead screw and nut pair (352). The control end of the micro stepper motor (351) is electrically connected to the controller (40). The micro stepper motor (351) drives the precision lead screw and nut pair (352) to rotate, causing the pressure plate (353) to move linearly along the axis of the rapid action mechanism (34), thereby precisely adjusting the preload length L of the spring (341) of the rapid action mechanism (34).

6. A method for compensating the contact pressure of an on-load tap changer for a transformer, applied to the contact pressure compensation system of the on-load tap changer as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Initial self-calibration steps: Before the system is put into operation for the first time or at the preset maintenance node, the controller (40) controls the on-load tap changer to perform a full tap range cycle operation in the no-load state. During this process, the initial static pressure value corresponding to each tap position when it is in steady-state closure is collected and recorded, and this value is calibrated as the static pressure reference value P0 of each tap position. The mapping relationship between tap position and static pressure reference is constructed and stored. S2: Static perception and pre-decision step: When the controller (40) receives an external gear shifting command, before performing any substantial mechanical switching action, the following sub-steps are inserted: S21: Obtain and read the raw pressure data P at the current tap position. 原始 The system uses real-time temperature data T and calls a preset temperature compensation function to adjust the original pressure data P. 原始 The calculation process is performed to eliminate the effects of temperature drift, resulting in the corrected static pressure value P. 校正 ; S22: Retrieve the static pressure reference value P0 corresponding to the current tap position, and set the corrected static pressure value P 校正 The value is compared with the static pressure reference value P0, and the following zoning decision logic is executed based on the comparison result: If P 校正 If ≥85% P0, it is determined to be a normal state, and the preset standard action parameters of the main drive motor (31) and the rapid action mechanism (34) are maintained, allowing the switching action to continue to be executed; If 60%P0≤P 校正 If <85%P0, it is determined to be in a compensation state. The spring pre-compression length compensation amount ΔL required to restore the contact pressure to the target level is calculated, and a first control command is generated to drive the spring pre-tension force adjustment device (35) to perform the compensation operation. At the same time, a second control command is generated to modify the action characteristic curve of the main drive motor (31) and increase its initial output torque. If P 校正 If the value is less than 60% of P0, it is considered a dangerous situation. The execution of this file transfer instruction will be immediately blocked, and a high-priority alarm signal will be generated. If P 校正 If the value is greater than 110%P0, it is considered an abnormal state, and a warning signal is generated to prompt for inspection or oil flushing operation. S3: Dynamic waveform acquisition step: During the transient process when the adaptive actuator (30) is allowed to perform tap switching action, the controller (40) continuously records the dynamic pressure fluctuation data output by the thin-film pressure sensor (23) at a sampling frequency of not less than 10kHz, forming a time-domain dynamic pressure characteristic waveform that characterizes the mechanical characteristics of this switching action, and extracts at least the peak value of the switching impact pressure P by analyzing the waveform. 峰值 Dynamic characteristic parameters including contact bounce count N and bounce amplitude, and the settling time T required for the contact to go from bounce to stable closure; S4: Health assessment and life prediction steps: The controller (40) at least comprehensively utilizes the dynamic characteristic parameters extracted from step S3, the working current monitoring value during this switching process, and the contact pressure attenuation change rate obtained from historical data, and uses the Kalman filter algorithm to make the optimal state estimate of the remaining effective thickness of the contact reflecting the degree of contact wear, and generates and outputs a quantitative assessment index characterizing the current health level of the contact based on the estimation results.

7. The method according to claim 6, characterized in that, In step S22, the spring pre-compression length compensation amount ΔL is calculated and determined according to the following formula: ΔL=k·(P0-P 校正 ); Where k is the system equivalent elastic coefficient associated with the stiffness coefficient of the rapid action mechanism (34) and the elastic modulus of the elastic support (22).

8. The method according to claim 6, characterized in that, In step S22, the operation of generating a second control command to modify the operating characteristic curve of the main drive motor (31) and increase its initial output torque specifically includes: The controller (40) outputs a modulated pulse width modulation signal to the servo driver of the main drive motor (31). By adjusting the duty cycle of the pulse width modulation signal, the working current of the main drive motor (31) at the beginning of the switching action is temporarily increased, thereby increasing its output torque to overcome the increase in mechanical resistance torque caused by the increase in the preload of the rapid action mechanism (34) after the spring preload adjustment device (35) performs the compensation operation.

9. The method according to claim 6, characterized in that, The quantitative assessment indicators generated in step S4 that characterize the current health level of the contact include at least one or more of the following: the percentage of remaining contact health and the estimated number of safe remaining operations.

10. The method according to claim 9, characterized in that, It also includes step S5: The quantitative evaluation indicators generated in step S4 are modeled and encapsulated according to the IEC 61850 communication protocol standard, and the encapsulated data is uploaded to a remote operation and maintenance monitoring platform through a network communication interface to realize the visualization of status display and early warning management on the platform.

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