Wide-width on-load voltage regulation dry-type transformer and voltage regulation method thereof

Abstract

The application discloses a wide-load regulation dry-type transformer and a voltage regulation method thereof, and relates to the technical field of transformers. The dry-type transformer comprises a three-phase three-column iron core, a high-voltage winding and a low-voltage winding. The high-voltage winding and the low-voltage winding are sequentially sleeved outside the iron core column. A plurality of multi-gear voltage regulation taps are arranged on the side wall of the high-voltage winding in a vertical direction. The multi-gear voltage regulation taps are laterally concentrated and led out from the upper part of the high-voltage winding and are connected to a load switch control box through an insulating closed bus transverse wiring. A load tap changer is arranged in the load switch control box. A plurality of static terminal groups are arranged in the load tap changer. The multi-gear voltage regulation taps are in one-to-one correspondence with the static terminal groups of the load tap changer and are connected to the static terminal groups. The multi-gear taps are electrically connected to the load switch control box, the dry-type transformer is accurately regulated, the wide-load regulation of the dry-type transformer is realized, and the stability and safety of the voltage regulation are improved.

Description

Technical Field

[0001] This invention relates to the field of power transformer technology, specifically to a wide-range on-load tap-changing dry-type transformer and its tap-changing method. Background Technology

[0002] Currently, dry-type transformers are widely used in industrial power distribution, data centers, and high-rise buildings—places with high power supply safety requirements—due to their advantages such as flame retardancy, explosion-proof properties, and ease of maintenance. However, most existing dry-type transformers adopt a fixed turns ratio design, which cannot meet the on-load voltage regulation requirements. When the grid voltage fluctuates significantly, it is difficult to regulate the voltage under load, usually requiring shutdown and tap switching, which seriously affects the continuity of power supply.

[0003] Current dry-type transformer designs attempt to incorporate on-load tap changing structures, but these often suffer from narrow tap ranges and poor insulation coordination between the tap changer and the transformer body. In particular, during tap changing, arcing interference is easily generated, and unreasonable connection designs for multi-tap positions frequently lead to faults such as poor contact and unbalanced three-phase regulation. This makes it impossible to meet the requirements for wide-range voltage regulation and to ensure the adaptability and operational safety of the equipment under complex operating conditions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a wide-range on-load tap-changing dry-type transformer and its tap-changing method. By setting up multiple taps and electrically connecting them to the on-load switch control box, and cooperating with an intelligent control system, the dry-type transformer is accurately tapped, thereby improving the tap-changing range of the dry-type transformer, realizing wide-range on-load tap-changing, and improving the stability and safety of tap-changing.

[0005] This invention provides a wide-range on-load tap-changing dry-type transformer, which includes a three-phase three-limb iron core, a high-voltage winding, and a low-voltage winding, wherein the high-voltage winding and the low-voltage winding are sequentially mounted on the outside of the iron core column; The high voltage winding sidewall is provided with multi-position voltage regulating taps arranged vertically. The multi-position voltage regulating taps are led out laterally from the upper part of the high voltage winding and connected to the on-load switch control box through insulated and enclosed busbars. The on-load tap changer is installed inside the on-load switch control box. The on-load tap changer has multiple sets of stationary terminals inside. The multi-position voltage regulating taps are plugged into and connected to the stationary terminals of the on-load tap changer one by one.

[0006] Furthermore, the high-voltage winding is a delta connection, the low-voltage winding is a star connection with a neutral line, and the on-load tap changer is based on a three-phase synchronous linkage structure and is connected to one of the several turns of the high-voltage winding with a rotary moving contact.

[0007] Furthermore, the on-load switch control box is rigidly fixed to the overall transformer frame by a metal bracket; The on-load tap changer is a three-phase integrated structure, and the on-load tap changer is internally equipped with a coaxial transmission assembly and a three-phase linkage contact assembly.

[0008] Furthermore, the on-load tap changer integrates a vacuum arc-extinguishing cavity and a current transition component. The vacuum arc-extinguishing cavity and the current transition component work together to perform multi-position switching actions to achieve a smooth transition transmission of load current in the dry-type transformer under load.

[0009] Furthermore, the on-load tap changer is equipped with an electric actuator, which is mechanically connected to the coaxial transmission assembly inside the on-load tap changer.

[0010] Furthermore, voltage and current acquisition transformers are installed at the output terminals of the low-voltage winding. The voltage acquisition transformer is used to acquire the output voltage of the low-voltage side of the transformer in real time, and the current acquisition transformer is used to acquire the load current of the low-voltage side of the transformer in real time.

[0011] Furthermore, the on-load switch control box is equipped with a temperature detection element and a gear position feedback detection element. The voltage acquisition transformer, current acquisition transformer, temperature detection element, and gear position feedback detection element are all connected to the voltage regulator controller signal to form a fully automatic voltage regulation signal acquisition and closed-loop control circuit.

[0012] The present invention also provides a voltage regulation method for a wide-range on-load tap-changing dry-type transformer, the voltage regulation method being applied to the wide-range on-load tap-changing dry-type transformer, the voltage regulation method comprising: The low-voltage side voltage and load current of the transformer are continuously and in real time collected using data acquisition elements, while the temperature of the on-load switch control box and the real-time tap position signal of the tap changer are collected simultaneously. The voltage regulator performs a summary calculation on the received operating parameters, and determines the range of voltage fluctuation deviation on the low-voltage side by combining the preset rated voltage, voltage regulation dead zone and delay judgment conditions. Based on the judgment value of the voltage fluctuation deviation range on the low-voltage side, the controller generates the corresponding voltage regulation command; The on-load tap changer controls the dry-type transformer by executing the voltage regulation command.

[0013] Furthermore, the step of generating a corresponding voltage regulation command through the controller based on the judgment value of the low-voltage side voltage fluctuation deviation range includes: The controller accurately matches the target adjustment level based on the voltage deviation value and the turns ratio parameters corresponding to the multi-stage taps of the high-voltage winding. The load current parameter is introduced for compensation and correction, and a voltage regulation command is generated in combination with the target adjustment level.

[0014] Furthermore, the voltage regulation method also includes: During gear switching, the target gear circuit is activated first to form a dual-circuit transitional conduction state, ensuring uninterrupted power supply to the load. The transient electric arc generated during gear switching is isolated and extinguished by a vacuum-sealed cavity, making it suitable for the insulation operation environment of dry-type transformers. The system monitors the temperature of the on-load switch control box and the transformer load rate in real time, and automatically locks out the voltage regulation action under heavy load or over-temperature abnormal conditions.

[0015] This invention optimizes the lead-out and connection method of multi-stage voltage regulating taps, using an insulated and enclosed busbar connected to an independent enclosed on-load tap changer control box, and in conjunction with a three-phase linkage dry-type vacuum on-load tap changer, achieving a wide range of on-load voltage regulation. This solves the problems of narrow voltage regulation range and the need for shutdown switching in existing technologies. The independently set on-load tap changer control box and insulating isolation baffle effectively isolate electric arc and heat, improving insulation performance and safety. The application of vacuum arc-extinguishing chamber and current transition component enables arc-free switching under load, ensuring power supply continuity. The fully automatic closed-loop control system, combined with multi-dimensional signal acquisition and interlocking control strategies, ensures the accuracy and operational stability of voltage regulation, effectively coping with complex operating conditions of large fluctuations in grid voltage. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a wide-range on-load tap-changing dry-type transformer in an embodiment of the present invention; Figure 2 This is a structural side view of a wide-width on-load tap-changing dry-type transformer in an embodiment of the present invention; Figure 3 This is a top view of the structure of the wide-width on-load tap-changing dry-type transformer in an embodiment of the present invention; Figure 4 This is a schematic diagram of the on-load tap changer control box of a wide-range on-load tap-changing dry-type transformer in an embodiment of the present invention; Figure 5 This is a flowchart of the voltage regulation method for a wide-range on-load tap-changing dry-type transformer in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Please refer to Figures 1 to 4 This invention provides a wide-range on-load tap-changing dry-type transformer. The dry-type transformer includes a three-phase, three-limb core 1, a high-voltage winding 2, and a low-voltage winding. The high-voltage winding 2 and the low-voltage winding are sequentially mounted on the outside of the core 1 limbs. The high-voltage winding 2 and the low-voltage winding can be formed by epoxy resin casting. Specifically, the core 1 is made of high-quality cold-rolled silicon steel sheets stacked together. The high and low voltage windings are formed into an integrated solid insulation structure through an epoxy resin vacuum casting and curing process. This structure not only has high mechanical strength but also excellent insulation performance and moisture resistance, enabling it to adapt to the harsh environment of oil-free operation of the dry-type transformer. During the winding manufacturing process, multiple taps 21 with adjustable voltage positions are arranged vertically on the sidewall of the high-voltage winding 2, and all taps 21 are led out laterally from the upper part of the winding. This "vertical arrangement" ensures a uniform difference in the number of turns between each tap, which is conducive to achieving linear and smooth voltage regulation. The "upper side centralized lead-out" design, compared with the traditional decentralized lead-out method, greatly optimizes the spatial layout of the transformer top, making the wiring more neat and orderly, and effectively avoiding the problem of insufficient insulation distance that may be caused by messy leads.

[0020] Furthermore, in this embodiment, the voltage regulating tap 21 is connected to the on-load tap changer control box 4 via a horizontally routed insulated busbar. The internal conductors of the insulated busbar are fully enclosed by insulating material, providing excellent insulation reliability and effectively preventing the influence of environmental factors such as dust and condensation on the conductive circuit. The horizontal routing design is simple and clear, reducing the structural space occupied between the dry-type transformer and the on-load tap changer control box 4, achieving a simple and orderly layout. A dry-type vacuum on-load tap changer 42 is fixedly installed inside the on-load tap changer control box 4. The tap changer 42 has multiple sets of stationary terminals 43 inside, and each voltage regulating tap 21 is plugged into and connected to the stationary terminals 43 of the tap changer 42. This plug-in connection method ensures the firmness and contact stability of the connection between the tap and the switch terminal, eliminating the potential for loosening or poor contact that may occur with traditional bolt connections from a physical structure perspective, laying the foundation for long-term reliable on-load voltage regulation.

[0021] In terms of circuit topology, the high-voltage winding 2 in this embodiment adopts a delta connection, while the low-voltage winding adopts a star connection with a neutral line. This classic connection combination can effectively suppress the third harmonic and ensure the purity of the output voltage waveform. The tap changer 42 adopts a three-phase synchronous linkage structure, which switches the connection state of different stationary terminals 43 by rotating the moving contact, selectively connecting different turns of the high-voltage winding 2 to form a multi-stage continuous adjustment structure, realizing wide-range on-load voltage regulation of the transformer. It should be understood that the so-called "wide range" means that the voltage regulation range can cover a large voltage fluctuation range, such as being able to adapt to the grid voltage fluctuation range of ±15% and above. Its working principle is as follows: when the grid voltage fluctuates, the moving contact of the tap changer 42 rotates under the drive of the electric mechanism, disconnecting the stationary terminal 43 of the current stage and connecting the stationary terminal 43 of the target stage, thereby changing the effective number of turns of the high-voltage winding 2 connected to the circuit. According to the law of electromagnetic induction, changing the number of turns on the primary winding changes the transformer's turns ratio, thus achieving a stable output voltage on the low-voltage side while keeping the number of turns in the low-voltage winding constant. The three-phase synchronous linkage structure ensures that the turns adjustment of the three-phase high-voltage winding 2 is completed at the same time, avoiding voltage imbalance or internal circulating current problems caused by asynchronous three-phase adjustment, and guaranteeing power supply quality.

[0022] Specifically, the on-load tap changer control box 4 is rigidly fixed to the overall transformer frame via a metal bracket. The metal bracket is typically welded from channel steel or angle steel, possessing sufficient mechanical strength to support the weight of the on-load tap changer control box 4 and its internal components. This rigid fixing method not only ensures the stability of the on-load tap changer control box 4 under transformer operating vibration conditions but also effectively prevents loose connections or poor contact caused by vibration. In this embodiment, an insulating isolation baffle is specifically provided between the on-load tap changer control box 4 and the winding body, forming an isolated, independent protective space between the voltage regulating switch area and the main transformer body. The insulating barrier is preferably made of high-insulation-strength materials such as SMC (Sheet Molding Compound) or epoxy resin board. It physically isolates the high-voltage energized winding main body from the operating area of ​​the tap changer 42, increasing the electrical clearance and creepage distance, and preventing transient overvoltages that may be generated during the operation of the tap changer 42 from damaging the insulation of the main body. At the same time, it can also serve as a barrier against dust and condensation, preventing dust or condensation on the winding surface from affecting the contact reliability of the tap changer 42, thereby significantly improving the safety of equipment operation.

[0023] Furthermore, the dry-type vacuum on-load tap changer 42, fixedly installed inside the on-load switch control box 4, is a three-phase integrated structure. Compared with the traditional mechanical connection scheme of three single-phase switches, this integrated structure integrates the core components of the three-phase switch into the same housing, greatly reducing the volume and improving the insulation coordination consistency between the three phases. The switch is equipped with a coaxial drive assembly and a three-phase linkage contact assembly, ensuring that the three-phase moving contacts rotate synchronously to ensure consistent adjustment of the number of turns in the three-phase high-voltage winding 2. Specifically, the coaxial drive assembly typically consists of a main drive shaft running through the three-phase switch body, driving the three-phase moving contacts to operate simultaneously via gears or linkage mechanisms. This mechanically forced synchronization fundamentally eliminates the problem of asynchronous three-phase switching caused by electrical control errors or mechanical action dispersion. It should be understood that if there is a time difference in the three-phase switching, even a difference on the order of milliseconds, it may generate a huge circulating current inside the transformer, leading to overheating or even damage to the windings. This embodiment, through the coaxial drive design, ensures absolute synchronization of three-phase voltage regulation, effectively avoiding three-phase voltage imbalance and internal circulating current problems.

[0024] In the on-load tap changer of this dry-type transformer, the electric actuator 41 is installed on the upper part of the control box and is the power source and control center of the entire switching process. It can receive external control commands or output power torque according to the preset voltage feedback signal. The on-load tap changer 42 is arranged in the control box below the electric actuator and is directly connected to the electric actuator 41 through a mechanical transmission mechanism. It integrates the main on / off contacts, transition contacts and current limiting resistors and is a key component for realizing on-load switching. The stationary terminals 43 are connected to the voltage regulating taps 21 of the transformer windings respectively. During operation, after receiving a voltage regulation command, the electric actuator drives the moving contact inside the tap changer to operate according to a preset program. First, it connects the current-limiting resistor and the transition contact to achieve a transition connection between adjacent taps without interrupting the load current. Then, it switches to the main on / off contact of the target tap position to complete one voltage regulation process. Throughout the process, a reliable electrical connection with the transformer winding is maintained through the stationary terminal block. Finally, the transformer ratio is adjusted by changing the effective number of turns of the transformer winding to stabilize the output voltage. At the same time, the current-limiting resistor can effectively suppress the circulating current during the switching process, prevent electric arc erosion of the contacts, and ensure the safe and stable operation of the equipment.

[0025] To achieve safe switching under load, the dry-type vacuum on-load tap changer 42 integrates a vacuum arc-extinguishing chamber and a current transition component. During the switching process, the transition component, in conjunction with the multi-position switching action, ensures a smooth transition of load current under load. Its working mechanism is as follows: when the tap changer 42 switches from one position to another, the moving contact does not jump directly, but rather forms a double-circuit conduction state within a short time through a branch formed by a transition resistor or transition reactance. At this time, the load current maintains continuous flow through the transition branch, avoiding power interruption. Simultaneously, the arc generated by the switching action is confined within the vacuum arc-extinguishing chamber. Due to the extremely high insulation strength and arc-extinguishing capability of the vacuum medium, the arc can be quickly extinguished when the current crosses zero without producing exposed sparks. This characteristic is particularly important for dry-type transformers, as they typically operate in air or enclosed, dry environments, lacking the oil arc-extinguishing and cooling medium of oil-immersed transformers. By applying a vacuum arc-extinguishing cavity, this embodiment successfully achieved "arc-free" switching, which not only protected the contacts from burning and extended the switch life, but also eliminated the impact of electric arc on the surrounding air insulation environment, truly realizing safe and continuous power supply during wide-range on-load voltage regulation.

[0026] Specifically, such as Figure 1 As shown, an electric actuator 41 is mounted on the top of the dry vacuum on-load tap changer 42. The electric actuator 41 is mechanically connected to the coaxial transmission assembly inside the switch. A fixed intelligent voltage regulator is mounted on the outside of the on-load switch control box 4. Specifically, the electric actuator 41, as the power source for voltage regulation, is typically composed of a servo motor and a reduction transmission unit. Its output shaft is directly coupled to the coaxial transmission assembly of the tap changer 42. When the intelligent voltage regulator issues a voltage increase or decrease command, the electric actuator 41 precisely drives the transmission shaft to rotate by a predetermined angle, thereby driving the internal moving contact assembly to complete the gear switching. The intelligent voltage regulator is fixedly installed on the outer wall of the on-load switch control box 4. This layout design utilizes the natural heat dissipation characteristics of the metal wall of the box to avoid the controller's electronic components being affected by the transformer's operating temperature. Furthermore, its location on the outside allows maintenance personnel to perform parameter tuning and status monitoring without opening the box, improving the system's maintainability.

[0027] To achieve precise automatic control, voltage and current acquisition transformers are installed at the low-voltage winding output terminals to collect real-time output voltage and load current parameters on the low-voltage side of the transformer. These voltage and current transformers typically employ a precision-cast structure, directly mounted on the low-voltage copper busbar leads, enabling real-time sensing of the power quality status on the load side. It should be understood that low-voltage side parameters are the direct basis for judging grid voltage fluctuations and load changes; their acquisition accuracy and real-time performance directly determine the accuracy of subsequent voltage regulation control. Furthermore, the on-load tap changer control box 4 is equipped with temperature detection elements and tap position feedback detection elements. The temperature detection element is preferably a Pt100 platinum resistance thermometer, attached to the insulating wall near the core contacts of the tap changer 42, used to monitor the micro-environmental temperature during switch operation, preventing overheating faults caused by increased contact resistance or poor heat dissipation. The tap position feedback detection element typically uses a photoelectric encoder or a cam-assisted switch, linked to the drive shaft of the tap changer 42, capable of converting the actual mechanical position of the moving contact into a digital signal and feeding it back to the controller.

[0028] The key to this embodiment lies in constructing a complete fully automatic voltage regulation signal acquisition and closed-loop control circuit. Voltage acquisition transformers, current acquisition transformers, temperature detection elements, and range feedback detection elements are all connected to the voltage regulator controller. Specifically, these acquisition elements transmit analog or digital signals to the signal processing module of the intelligent voltage regulator controller via shielded cables. The microprocessor inside the controller performs comprehensive calculations on voltage deviation, load current, temperature status, and the current range based on a preset logic algorithm. For example, when the voltage transformer detects that the output voltage is lower than the set lower limit for a certain delay, while the temperature and load current are within the allowable range, the controller sends a voltage boosting command to the electric actuator 41. After the action is completed, the range feedback detection element sends back the new range signal. The controller confirms whether the voltage regulation action was successfully executed by comparing the commanded range with the feedback range. This closed-loop architecture of "acquisition-calculation-execution-feedback" completely eliminates the traditional manual voltage regulation mode at the hardware level, providing a solid physical foundation for wide-range automatic voltage stabilization of transformers in unattended environments.

[0029] Example 2: Please refer to Figure 5 The present invention also provides a voltage regulation method for a wide-range on-load tap-changing dry-type transformer, the voltage regulation method comprising: Step S1: Continuously collect the low-voltage side voltage and load current of the transformer in real time using the acquisition element, and simultaneously collect the temperature of the on-load switch control box 4 and the real-time tap position signal of the tap changer 42.

[0030] Specifically, voltage and current acquisition transformers monitor the effective value of the output voltage and the magnitude of the load current on the low-voltage side of the transformer, respectively. These electrical parameters are the direct basis for determining whether voltage regulation is needed. Simultaneously, a temperature detection element located in the on-load tap changer control box 4 monitors the operating environment temperature of the tap changer 42 in real time, preventing overheating risks caused by increased contact resistance or poor heat dissipation. The tap position feedback detection element captures the current mechanical position of the moving contact in real time, providing status feedback to the controller. All acquired signals are transmitted in real time to the signal processing module of the intelligent voltage regulator controller via shielded cables, ensuring the real-time performance and accuracy of the data.

[0031] Step S2: The voltage regulator performs a summary calculation on the received operating parameters, and determines the voltage fluctuation deviation range on the low-voltage side by combining the preset rated voltage, voltage regulation dead zone and delay judgment conditions.

[0032] A permissible voltage fluctuation range is set (e.g., ±1% or ±2.5% of the rated voltage). When the voltage fluctuation falls within this dead zone, the controller considers it acceptable and does not trigger an adjustment command. Simultaneously, a "delay judgment" logic is introduced: when the voltage exceeds the dead zone, the controller does not act immediately but starts a timer. Only when the voltage continues to exceed the range for a preset time (e.g., 10 to 30 seconds), confirming it as a continuous fluctuation rather than a transient disturbance, does it proceed to the next adjustment step. This dual judgment mechanism effectively shields against voltage flicker caused by short-term load surges, greatly improving system stability.

[0033] Step S3: When the voltage exceeds the qualified range and meets the delay judgment requirements, the controller generates the corresponding boost or buck adjustment command.

[0034] Specifically, if the real-time voltage is lower than the lower limit of the rated voltage and remains so for a certain period, the controller generates a "boost" command to reduce the effective number of turns in the high-voltage winding 2 to increase the output voltage on the low-voltage side; conversely, if the voltage is higher than the upper limit, a "buck" command is generated. During the command generation process, the controller also comprehensively judges the current load current and temperature status. If the device is under heavy load or over-temperature abnormal conditions, the controller prioritizes blocking command generation to ensure equipment safety.

[0035] Step S4: Execute the voltage regulation command based on the on-load switch control box 4 to perform on-load voltage regulation on the dry-type transformer.

[0036] The servo motor within the electric actuator 41 receives pulse control signals and drives the drive shaft to rotate via a reduction gearbox. Since the tap changer 42 adopts a three-phase integrated structure, the rotation of the drive shaft directly drives the three-phase moving contact assembly to rotate synchronously. During rotation, the moving contact disengages from the stationary terminal 43 of the current tap position and establishes a connection with the stationary terminal 43 of the target tap position, thereby physically changing the number of turns in the high-voltage winding 2 connected to the circuit. Based on the principle of electromagnetic induction, the change in the number of turns on the high-voltage side changes the transformer's turns ratio, thus regulating the output voltage on the low-voltage side.

[0037] At the instant the moving contact switches from one position to another, a transition component (such as a transition resistor) intervenes, creating a brief "bridging" state. This means that both the old and new position circuits are simultaneously conducting, and the load current flows continuously through the transition branch, preventing power interruption. Simultaneously, the electric arc generated during the switching process is confined within the vacuum arc-extinguishing chamber. Due to the extremely high dielectric recovery strength of the vacuum medium, the arc extinguishes rapidly and does not leak when the current crosses zero, thus achieving arc-free switching under load and ensuring power supply continuity and equipment insulation safety.

[0038] Specifically, in this embodiment, the acquisition element is set to acquire four core parameters synchronously at a frequency of 1 second / time to ensure data synchronization and avoid timing deviations affecting algorithm judgment. The four core parameters include: low-voltage side voltage, load current, temperature of on-load switch control box 4, and real-time tap position of tap changer 42.

[0039] Preprocess the collected data: The low-voltage side voltage collected each time is filtered. Combined with the voltage values ​​of the most recent 5 sampling periods, the median average is used to obtain the filtered voltage. In this embodiment, it is assumed that the original voltages of the current 5 sampling periods are 388V, 390V, 389V, 392V, and 387V. The maximum value of 392V and the minimum value of 387V are removed. The remaining voltage data of 388V, 390V, and 389V are averaged to obtain the filtered voltage value of 389V. Furthermore, after each sampling and filtering is completed, the five historical voltage values ​​in the cache are updated, and the current filtered voltage value is used as the fifth voltage value. The data of the five historical voltage values ​​are updated sequentially. If the temperature (T>85℃) of the on-load switch control box 4 or the real-time tap position of the tap changer 42 exceeds the range of -2 to +2, it will be directly marked as "constraint abnormal" and will not proceed to subsequent calculations. Only data will be continuously collected to reduce the impact of errors.

[0040] Specifically, the instantaneous voltage deviation and deviation score are calculated using a 400V rated voltage as a benchmark. The rated voltage is subtracted from the latest filtered voltage, the difference is divided by the rated voltage, and finally multiplied by 100% to obtain the instantaneous voltage deviation rate, which quantifies the degree of voltage deviation from the rated value. The deviation is quantified by a scoring system to avoid fuzzy judgment. When the instantaneous voltage deviation rate is not higher than -2.5% (i.e., the voltage is not higher than 390V), it is considered a serious undervoltage, and the deviation score is 90 to 100 points. When the instantaneous voltage deviation rate is between -2.5% and -1% (i.e., the voltage is between 390V and 396V), it is considered a slight undervoltage, with a deviation score of 60 to 89. When the instantaneous voltage deviation rate is between -1% and 1% (i.e., the voltage is between 396V and 404V), it is within the normal range, and the deviation score is between 0 and 59. When the instantaneous voltage deviation rate is between 1% and 2.5% (i.e., the voltage is between 404V and 410V), it is considered a slight overvoltage, with a deviation score of 60 to 89. When the instantaneous voltage deviation rate is not less than 2.5% (i.e., the voltage is not less than 410V), it is considered a serious overvoltage, with a deviation score of 90 to 100 points. Furthermore, the persistence and score of the voltage trend are determined based on the five most recent filtered voltage values ​​in the cache. The determination is made as to whether the voltage exhibits a "continuous deviation in the same direction" from the rated value, rather than random fluctuations. The specific rules are as follows: All five voltage values ​​are not higher than 396V (corresponding to a deviation rate not higher than -1%), and the voltage values ​​show a "non-decreasing" trend (allowing for minor fluctuations of ±0.5V), indicating a stable trend, with a trend score of 80 to 100 points; All five voltage values ​​are not lower than 404V (corresponding to a deviation rate of not less than 1%), and the voltage values ​​show a "non-increasing" trend (allowing for minor fluctuations of ±0.5V), indicating a stable trend, with a trend score of 80 to 100 points; If the five voltage values ​​fluctuate within the normal range of 396V to 404V, or if they are within the same deviation range but do not show a clear trend in the same direction (such as fluctuating between high and low), it indicates that the trend is unstable, and the trend score is 0 to 30 points. If 3 to 4 out of 5 voltage values ​​are in the deviation range and 1 to 2 are in the normal range, it indicates that the trend is unclear, and the trend score is 30 to 79 points.

[0041] Furthermore, the constraint conditions are determined and the constraint scores are calculated; the temperature of the on-load tap changer control box 4 and the current tap position of the tap changer 42 are linked to prevent frequent voltage adjustments and over-range voltage adjustments from damaging the equipment. The specific rules are as follows: When the temperature of the on-load switch control box does not exceed 65℃ and the tap changer position is between -2 and +2 (not the limit position), there are no constraints and the voltage can be adjusted normally. The constraint score is 80 to 100 points. When the temperature of the on-load switch control box is between 65℃ and 85℃, and the tap changer position is between -2 and +2, it is considered a weak constraint, and the voltage regulation judgment is weakened. The constraint score is 40 to 79 points. When the temperature of the on-load switch control box exceeds 85℃, or when the tap changer is in -2 (lowest setting) or +2 (highest setting), it is considered a strong constraint, which blocks the voltage regulation action, and the constraint score is 0 to 39 points. Calculation of overall weighted score: The overall score is obtained by weighted summation of three parts. In this embodiment, the weight of the instantaneous deviation score is set to 0.5, the weight of the voltage trend duration score is 0.3, and the weight of the constraint condition score is 0.2. That is, the instantaneous deviation score multiplied by 0.5, plus the voltage trend duration score multiplied by 0.3, plus the constraint condition score multiplied by 0.2, combined with a preset 70-point trigger threshold, determines whether the voltage fluctuation is a "true long-term offset," replacing the traditional deviation range judgment. If the overall score reaches 70 points or above: it is judged as "true long-term voltage deviation" and voltage regulation is required; If the overall score is below 70 points, it is judged as "instantaneous interference and slight oscillation". No voltage adjustment is required, and the current gear remains unchanged.

[0042] Specifically, by combining real-time tap position feedback, temperature, and load condition signals for closed-loop verification and interlocking control, the transformer ratio is dynamically stabilized, achieving wide-range automatic stable output of the low-voltage side voltage. After the tap position switching action is completed, the tap position feedback detection element sends the new actual tap position signal back to the controller. The controller compares it with the commanded target tap position. If they match, the action is considered successful; otherwise, a fault alarm is triggered. In addition, the system continuously monitors the temperature of the on-load tap changer control box 4 and the transformer load rate. Once abnormal conditions such as heavy load or over-temperature are detected, subsequent voltage regulation actions are immediately and automatically blocked to prevent equipment damage caused by forced operation under harsh conditions. Through this closed-loop feedback and interlocking protection mechanism, the long-term, safe, and automatic stable operation of the transformer is ensured in a wide-range voltage fluctuation environment.

[0043] Specifically, the voltage regulation method further includes: the controller precisely matching the target adjustment level based on the voltage deviation value and the turns ratio parameters corresponding to the multiple taps of the high-voltage winding 2. The intelligent voltage regulator controller internally stores a table of turns ratios or turns ratio parameters corresponding to each tap of the high-voltage winding 2. When a voltage deviation is detected, the controller does not simply issue a voltage increase or decrease command, but calculates the specific turns adjustment required to eliminate the deviation, and then queries the parameter table to lock in the unique target level. For example, if the current voltage deviation is -3%, and the controller calculates that the number of turns in the high-voltage winding 2 needs to be reduced by 2% to accurately offset the deviation, it will directly match to the level corresponding to the 2% reduction in turns, rather than trying each level one by one. This precise matching mechanism avoids repeated adjustments and improves voltage regulation efficiency.

[0044] Secondly, load current parameters are introduced for compensation and correction to suppress voltage misjudgment and frequent adjustments caused by instantaneous load surges. It should be understood that the start-up and shutdown of large load equipment can cause instantaneous drops or surges in grid voltage, which usually return to normal within seconds. If the controller does not distinguish these fluctuations, it is highly likely to trigger malfunctions. In this embodiment, the controller monitors the rate of change of load current in real time. When a sudden change in current is detected exceeding a preset threshold (e.g., 20% of the rated current), it is determined to be an instantaneous surge. At this time, the controller automatically increases the tolerance for voltage deviation or temporarily freezes the adjustment logic until the current returns to stability. This load current-based compensation and correction logic effectively shields false voltage signals, prevents frequent and unnecessary actions of the tap changer 42, and significantly extends the service life of mechanical components.

[0045] Finally, the output synchronous drive signal controls the synchronous switching of the three-phase moving contacts to maintain consistent parameters in the three-phase voltage regulation circuit, avoiding three-phase voltage imbalance and internal circulating current. The tap changer 42 adopts a three-phase integrated structure, and this embodiment further enhances synchronization at the control level. The controller sends a synchronous drive command containing phase information to the electric actuator 41 to ensure that the three-phase moving contacts achieve microsecond-level synchronization accuracy in mechanical action when the drive motor drives the coaxial transmission component. If there is a time difference in the three-phase switching, even a very short time difference, it will generate a huge circulating current inside the transformer, causing the winding to overheat. This embodiment ensures the consistency of the adjustment of the number of turns of the three-phase high-voltage winding 2 through synchronous control combining hardware and software, fundamentally eliminating the hidden danger of three-phase voltage imbalance and ensuring a high standard of power supply quality output.

[0046] First, during gear switching, the target gear circuit is activated first to form a dual-circuit transition state, ensuring uninterrupted power supply to the load.

[0047] When the moving contact of tap changer 42 switches from the current tap (e.g., tap N) to the target tap (e.g., tap N+1), it does not directly disconnect the current tap. Instead, it first contacts the stationary terminal 43 of the target tap through the transition resistor branch in the transition component. At this time, within a very short time window (usually on the order of milliseconds), the moving contact simultaneously connects the current tap and the target tap, forming a dual-circuit parallel conduction state. The core of this mechanism lies in the current-limiting effect of the transition resistor, which can effectively limit the circulating current generated between the two taps due to the potential difference of the number of turns, preventing short circuits. The load current then smoothly transitions through this parallel path, thereby ensuring that the power supply to the low-voltage side of the transformer is never interrupted during the entire mechanical operation, achieving a truly "seamless" switching.

[0048] Secondly, the transient electric arc generated during gear switching is isolated and extinguished by a vacuum-sealed cavity, making it suitable for the insulation operation environment of dry-type transformers.

[0049] It should be understood that after the dual-circuit transition, the moving contact needs to disconnect from the original position, and this "opening" is inevitably accompanied by the generation of an electric arc. In this embodiment, all contact opening actions occur inside the vacuum arc-extinguishing chamber. The vacuum medium has extremely high insulation strength and extremely fast dielectric recovery speed. When the contacts separate in the vacuum, the electric arc is extinguished instantaneously at the current zero-crossing point, and no sparks or high-temperature ionized gases are ejected outward. This is particularly critical for dry-type transformers, because dry-type transformers typically operate in an air-insulated environment and lack the arc-extinguishing and cooling functions of transformer oil. Through the sealed isolation of the vacuum arc-extinguishing chamber, the potential damage of the electric arc to the surrounding air-insulated medium and epoxy resin windings is completely eliminated, fire hazards are eliminated, and the insulation safety of the equipment during frequent load voltage regulation is ensured.

[0050] Finally, the temperature of the on-load switch control box 4 and the transformer load rate are monitored in real time. Under heavy load and over-temperature abnormal conditions, the voltage regulation action is automatically locked to ensure the safe operation of wide-range long-term automatic voltage regulation.

[0051] The intelligent voltage regulator controller reads data from the temperature detection element and current transformer in real time and performs logical judgments. For example, when the internal temperature of the on-load tap changer box 4 exceeds a preset high-temperature threshold (e.g., 120°C), or the transformer load rate exceeds a heavy-load threshold (e.g., 110% or 120% of the rated capacity), the controller determines that the current operating conditions are not suitable for mechanical switching operations. At this time, the system automatically triggers the interlocking logic, prohibiting the execution of any voltage increase or decrease commands and issuing a warning signal. This design avoids equipment damage caused by mechanical jamming, contact overheating and welding risks under extreme operating conditions, demonstrating the system's self-protection capability in extreme environments and significantly extending the service life of the on-load tap changer 42.

[0052] Specifically, data centers, as locations with concentrated high-computing loads, have extremely high requirements for the stability and continuity of power supply voltage. Voltage fluctuations are typically required to be controlled within ±5% of the rated voltage, and power outages are strictly prohibited. The high-voltage winding 2 of the transformer has multiple taps 21 arranged vertically along its sidewall. All taps 21 are led out laterally from the upper part of the winding and connected to the independent, enclosed on-load tap changer control box 4 on the side of the transformer body via insulated busbars. This structural layout is particularly suitable for the compact space and high cleanliness requirements of data center computer rooms. The insulated busbars effectively prevent the risk of creepage and flashover caused by dust accumulation, while the independent, enclosed on-load tap changer control box 4 completely isolates the debris and arc generated by switching operations outside the main unit, ensuring a clean and safe computer room environment.

[0053] In actual operation, when the input voltage fluctuates drastically due to excessive peak-valley differences in the external power grid—for example, when the voltage drops to 85% of the rated value (i.e., a -15% deviation) during peak electricity consumption periods, or rises to 115% of the rated value (i.e., a +15% deviation) during off-peak periods at night—the automatic voltage regulation system of this invention immediately activates its response mechanism. Voltage and current sensing transformers installed at the low-voltage winding output terminals capture the voltage deviation signal in real time and transmit it to the intelligent voltage regulator controller.

[0054] The intelligent voltage regulator controller executes actions according to a preset automatic voltage regulation method. First, it determines that the voltage deviation has exceeded the preset dead zone range (e.g., ±2.5%), then initiates a delay-based judgment logic to confirm that the deviation is a continuous fluctuation rather than a momentary disturbance. Subsequently, the controller generates corresponding boost or buck regulation commands to drive the electric actuator 41. Thanks to the vacuum arc-extinguishing chamber and current transition components integrated within the dry-type vacuum on-load tap changer 42, the transformer completes tap switching under load, with no arc leakage and no power interruption throughout the process.

[0055] Actual measurements showed that when the grid input voltage fluctuated drastically by ±15%, the transformer in this embodiment could stabilize the low-voltage side output voltage within ±2% of the rated voltage within a time range of milliseconds to seconds (the specific response time depends on the speed and range of the electric actuator 41, typically less than 3 seconds for a single switch). This was achieved by changing the effective number of turns in the high-voltage winding 2. This excellent voltage regulation performance ensures that sensitive loads such as servers and storage devices in the data center always operate within the optimal voltage window, avoiding server downtime due to excessively low voltage or accelerated equipment aging caused by excessively high voltage. Simultaneously, the three-phase synchronous linkage structure ensures the balance of the three-phase output voltage, effectively suppressing the impact of three-phase voltage imbalance on the power modules of precision IT equipment.

[0056] Furthermore, under the high-temperature and high-load operating conditions of data centers in summer, the temperature detection element installed in the on-load switch control box 4 monitors the switch operating temperature in real time. Once the temperature of the on-load switch control box 4 exceeds the preset safety threshold, the system automatically triggers the interlocking logic, suspending the voltage regulation operation to prevent equipment overheating and damage. The voltage regulation function is automatically resumed after the cooling system reduces the temperature to a safe range. This intelligent operating condition management mechanism greatly improves the reliability and safety of the power supply system in extreme environments, perfectly meeting the stringent requirements of data centers for "zero interruption" power supply continuity.

[0057] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc.

[0058] Furthermore, the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A wide-range on-load tap-changing dry-type transformer, characterized in that, The dry-type transformer includes a three-phase three-limb iron core, a high-voltage winding, and a low-voltage winding, with the high-voltage winding and the low-voltage winding sequentially mounted on the outside of the iron core column; The high voltage winding sidewall is provided with multi-position voltage regulating taps arranged vertically. The multi-position voltage regulating taps are led out laterally from the upper part of the high voltage winding and connected to the on-load switch control box through insulated and enclosed busbars. The on-load tap changer is installed inside the on-load switch control box. The on-load tap changer has multiple sets of stationary terminals inside. The multi-position voltage regulating taps are plugged into and connected to the stationary terminals of the on-load tap changer one by one.

2. The wide-range on-load tap-changing dry-type transformer as described in claim 1, characterized in that, The high-voltage winding is a delta connection, the low-voltage winding is a star connection with a neutral line, and the on-load tap changer is based on a three-phase synchronous linkage structure and is connected to one of several turns of the high-voltage winding with a rotary moving contact.

3. The wide-range on-load tap-changing dry-type transformer as described in claim 1, characterized in that, The on-load switch control box is rigidly fixed to the overall frame of the transformer by a metal bracket. The on-load tap changer is a three-phase integrated structure, and the on-load tap changer is internally equipped with a coaxial transmission assembly and a three-phase linkage contact assembly.

4. The wide-range on-load tap-changing dry-type transformer as described in claim 1, characterized in that, The on-load tap changer integrates a vacuum arc-extinguishing chamber and a current transition component. The vacuum arc-extinguishing chamber and the current transition component work together to perform multi-position switching actions to achieve a smooth transition transmission of load current in the dry-type transformer under load.

5. The wide-range on-load tap-changing dry-type transformer as described in claim 1, characterized in that, The on-load tap changer is equipped with an electric actuator, which is mechanically connected to the coaxial transmission assembly inside the on-load tap changer.

6. The wide-range on-load tap-changing dry-type transformer as described in claim 1, characterized in that, Voltage and current acquisition transformers are installed at the output terminals of the low-voltage winding. The voltage acquisition transformer is used to acquire the output voltage of the low-voltage side of the transformer in real time, and the current acquisition transformer is used to acquire the load current of the low-voltage side of the transformer in real time.

7. The wide-range on-load tap-changing dry-type transformer as described in claim 6, characterized in that, The on-load switch control box is equipped with a temperature detection element and a gear position feedback detection element. The voltage acquisition transformer, current acquisition transformer, temperature detection element, and gear position feedback detection element are all connected to the voltage regulator controller signal to form a fully automatic voltage regulation signal acquisition and closed-loop control circuit.

8. A voltage regulation method for a wide-range on-load tap-changing dry-type transformer, characterized in that, The voltage regulation method is applied to the wide-range on-load tap-changing dry-type transformer as described in any one of claims 1 to 7, and the voltage regulation method comprises: The low-voltage side voltage and load current of the transformer are continuously and in real time collected using data acquisition elements, while the temperature of the on-load switch control box and the real-time tap position signal of the tap changer are collected simultaneously. The voltage regulator performs a summary calculation on the received operating parameters, and determines the range of voltage fluctuation deviation on the low-voltage side by combining the preset rated voltage, voltage regulation dead zone and delay judgment conditions. Based on the judgment value of the voltage fluctuation deviation range on the low-voltage side, the controller generates the corresponding voltage regulation command; The on-load tap changer controls the dry-type transformer by executing the voltage regulation command.

9. The voltage regulation method for a wide-range on-load tap-changing dry-type transformer as described in claim 8, characterized in that, The step of generating a corresponding voltage regulation command through the controller based on the judgment value of the low-voltage side voltage fluctuation deviation range includes: The controller accurately matches the target adjustment level based on the voltage deviation value and the turns ratio parameters corresponding to the multi-stage taps of the high-voltage winding. The load current parameter is introduced for compensation and correction, and a voltage regulation command is generated in combination with the target adjustment level.

10. The voltage regulation method for a wide-range on-load tap-changing dry-type transformer as described in claim 8, characterized in that, The voltage regulation method further includes: During gear switching, the target gear circuit is activated first to form a dual-circuit transitional conduction state, ensuring uninterrupted power supply to the load. The transient electric arc generated during gear switching is isolated and extinguished by a vacuum-sealed cavity, making it suitable for the insulation operation environment of dry-type transformers. The system monitors the temperature of the on-load switch control box and the transformer load rate in real time, and automatically locks out the voltage regulation action under heavy load or over-temperature abnormal conditions.

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