A kind of intelligent adjustment transition resistance on-load tap changer device and control method

Abstract

This invention discloses an on-load tap changer device and control method for intelligently adjusting transition resistance. The device includes a main circuit and a transition circuit. The main circuit includes a tap selection switch and a vacuum circuit breaker, while the transition circuit includes an intelligent transition resistor, a vacuum circuit breaker, and an intelligent resistor controller. The intelligent transition resistor is a controllable sliding rheostat or a controllable series-parallel resistor. The intelligent resistor controller calculates the optimal transition resistance value based on a multi-objective genetic algorithm and achieves intelligent adjustment. The control method detects voltage fluctuations on the load side using a voltage sensor. After triggering tap selection, the intelligent resistor controller optimizes the transition resistance value. This, combined with the on / off switching of the vacuum circuit breaker in the main and transition circuits and the action of the tap selection switch, enables arc-free voltage regulation across tap positions in the on-load tap changer. This invention can dynamically adjust the transition resistance according to real-time operating conditions, reducing voltage and current fluctuations and improving grid voltage stability and power quality.

Description

Technical Field

[0001] This invention relates to an on-load tap changer device and control method, and more particularly to an on-load tap changer device and control method with intelligent adjustment of transition resistance. Background Technology

[0002] The most important technical indicator for measuring power quality is voltage stability, as voltage fluctuations directly affect the safe and economical operation of the power grid. On-load tap-changing transformers utilize on-load tap-changers (OLTCs) to achieve on-load voltage regulation, which not only stabilizes the load center voltage but also further ensures power quality, offering advantages such as strong regulation capability, high flexibility, and convenient operation. Therefore, since the 1990s, on-load tap-changing technology has gradually replaced off-load tap-changing, becoming the most mainstream voltage regulation mode in this field.

[0003] Currently, the commonly used tap changer switching method in OLTCs is fixed tap changer switching, meaning the tap position during the transition process is fixed, typically selecting the middle tap position from all on-load tap changers. This method offers convenient electrical wiring, a simple operating principle, and eliminates the need for separate design for each tap position in the transition sequence. However, it also necessitates that the transition resistor capacity must be designed based on the voltage difference between the middle and highest or lowest tap positions, and that voltage fluctuations and losses are significant when switching between taps adjacent to the transition position. Furthermore, current on-load tap changers are mostly used for sequential tap adjustment, which cannot quickly adjust to the required tap position under conditions of large voltage load changes, resulting in slow voltage regulation response and difficulty in adapting to scenarios with significant voltage load fluctuations caused by the grid connection of new energy sources such as wind power and photovoltaics. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to propose an intelligent on-load tap changer device and control method for adjusting the transition resistance. It can intelligently adjust the transition resistance of the on-load tap changer of the transformer according to the real-time operating conditions, reduce voltage and current fluctuations, and realize cross-taper voltage regulation, enabling the OLTC to respond to voltage fluctuations more quickly, thereby improving the voltage stability and power quality of the power grid.

[0005] Technical solution: The present invention includes a main circuit, a transition circuit and an intelligent resistor controller. The main circuit is connected to the transformer winding and the neutral point of the high-voltage end of the transformer. One end of the transition circuit is connected to the intermediate tap of the transformer winding and the other end is connected to the neutral point of the high-voltage end of the transformer. The intelligent resistor controller is electrically connected to the transition circuit.

[0006] The main circuit includes a gear selection switch group and a first vacuum circuit breaker connected in sequence. The gear selection switch group includes several gear selection switches connected in parallel. One end of each gear selection switch is connected to a different tap of the transformer winding, and the other end is connected to one end of the first vacuum circuit breaker. The other end of the first vacuum circuit breaker is connected to the neutral point of the high-voltage side of the transformer.

[0007] The transition circuit includes an intelligent transition resistor and a second vacuum circuit breaker connected in sequence. One end of the intelligent transition resistor is connected to the intermediate tap of the transformer winding, and the other end of the second vacuum circuit breaker is connected to the neutral point of the high-voltage end of the transformer. The intelligent resistor controller is electrically connected to the intelligent transition resistor and is used to control the resistance adjustment of the intelligent transition resistor.

[0008] The intelligent resistor controller has a built-in multi-objective genetic algorithm module for calculating the optimal resistance value of the intelligent transition resistor under different gear switching conditions.

[0009] Furthermore, the number of gear selection switching switch groups is matched with the number of transformer winding taps, with five or more transformer winding taps. Each gear selection switching switch is a high-voltage arc-free switching switch, which can achieve smooth switching in the event of a power outage.

[0010] Furthermore, both the first and second vacuum circuit breakers are high-voltage vacuum switches used to switch the operating current and transition current of the on-load tap changer, thereby preventing the generation of electric arcs in the transformer oil, reducing the generation of decomposition gases in the transformer oil, and reducing the rise in oil temperature.

[0011] Furthermore, when the intelligent transition resistor is a controllable sliding rheostat, the intelligent resistor controller is electrically connected to the slider drive mechanism of the controllable sliding rheostat, and the resistance value is adjusted by controlling the movement of the slider; when the intelligent transition resistor is a controllable series-parallel resistor, the intelligent resistor controller is electrically connected to each branch switch of the controllable series-parallel resistor, and the resistance value is adjusted by controlling the on / off state of the branch switches, so that the intelligent transition resistor matches the optimal resistance value of the current gear switching condition.

[0012] Furthermore, the device also includes a voltage sensor, which is installed on the load side of the transformer and connected to the intelligent resistor controller. The voltage sensor is used to detect the voltage waveform on the load side of the transformer and transmit the voltage signal to the intelligent resistor controller, providing voltage data for gear switching triggering and optimal resistance value calculation.

[0013] Furthermore, the device also includes a temperature sensor, which is installed inside the oil chamber of the on-load tap changer and is signal-connected to the intelligent resistor controller. The temperature sensor is used to detect the oil chamber temperature and transmit the temperature signal to the intelligent resistor controller, providing temperature data for the multi-objective genetic algorithm to calculate the optimal resistance value.

[0014] A method for controlling an on-load tap changer with intelligent adjustment of transition resistance based on the above-mentioned device includes the following steps:

[0015] S1: The voltage waveform on the load side of the transformer is detected by a voltage sensor. When the load voltage fluctuation exceeds the threshold of the gear switching voltage limit, the intelligent resistor controller calculates the target gear switching according to the set voltage and triggers the gear switching working signal.

[0016] S2: After receiving the working signal, the intelligent resistor controller calculates the optimal resistance value of the intelligent transition resistor under the current working condition based on the multi-objective genetic algorithm, combined with the current initial gear, target switching gear, oil chamber temperature and gear switching transition time, and controls the intelligent transition resistor to adjust to the optimal resistance value.

[0017] S3: Close the second vacuum circuit breaker and connect the transition circuit so that the initial position of the on-load tap changer works in coordination with the transition circuit;

[0018] S4: Disconnect the first vacuum circuit breaker, cut off the main circuit, and make the on-load tap changer only operate in the transition circuit;

[0019] S5: Disconnect the gear selection switch corresponding to the initial gear position and close the gear selection switch corresponding to the target gear position to realize gear switching in the power-off state. This gear switching can realize direct switching across gears without the need for sequential switching.

[0020] S6: Close the first vacuum circuit breaker and connect to the main circuit, so that the target tap position of the on-load tap changer and the transition circuit work together;

[0021] S7: Disconnect the second vacuum circuit breaker, cut off the transition circuit, and complete the tap changer switching.

[0022] Furthermore, the optimization variables of the multi-objective genetic algorithm in step S2 are X=(x1, x2, x3)=(R,T, t), where R is the resistance value of the intelligent transition resistor (Ω), T is the room temperature rise of the on-load tap changer oil (°C), and t is the on-load tap changer switch transition time (s); the optimization objectives are min(R), min(T), and min(t), which respectively achieve the goals of reducing resistance loss, ensuring equipment safety and extending insulation life, and reducing power grid fluctuations.

[0023] Furthermore, the specific process of calculating the optimal resistance value based on the multi-objective genetic algorithm in step S2 is as follows:

[0024] S21: Within the inequality constraints of the optimization variables, determine the possible value range of the variables based on practical engineering experience, and use the Latin hypercube sampling method to generate an initial parent population with a total number of N=50.

[0025] S22: Perform selection, crossover, and mutation operations on the initial parent population to generate a new offspring population;

[0026] S23: Merge the new offspring population with the previous generation population, solve for the fitness value of the merged population, and perform non-dominated sorting.

[0027] S24: Calculate the crowding degree of the non-dominated ordination layer and select individuals that meet the conditions to form a new parent population;

[0028] S25: Determine whether the stopping criterion is met. If it is met, output the Pareto optimal solution; otherwise, return to step S22.

[0029] The stopping criterion in step S25 is: all individuals are in the same level set after non-dominated sorting; the optimal intelligent transition resistor value in the Pareto optimal solution set is the resistance value that satisfies the actual working conditions of the project in the first non-dominated level.

[0030] Beneficial effects: The present invention has the following advantages:

[0031] (1) The present invention uses a controllable intelligent transition resistor, and realizes real-time dynamic adjustment of the resistance value through an intelligent resistor controller, so that the capacity of the transition resistor matches the actual voltage difference of the gear switching, avoiding the problem of large voltage fluctuation and high loss caused by fixed resistor switching, and effectively reducing voltage and current fluctuations.

[0032] (2) This invention applies a multi-objective genetic algorithm to optimize the resistance value of the transition resistor of the on-load tap changer. The transition resistor value, oil temperature rise and switching time are multi-objective optimization variables, which realizes the accurate calculation of the optimal resistance value. It takes into account multiple objectives such as reducing losses, ensuring equipment safety and reducing power grid fluctuations, and extends the insulation life of the on-load tap changer and transformer.

[0033] (3) This invention achieves direct voltage regulation across gears under power outage conditions by using the switching of vacuum circuit breakers through the coordinated control of the main circuit and the transition circuit, which solves the problem of slow response of traditional sequential gear regulation, can quickly adapt to large fluctuations in voltage load, and improves the response speed of grid voltage fluctuations.

[0034] (4) The device of the present invention has a simple structure. The number of tap selection switching groups can be flexibly expanded according to the number of transformer winding taps. It is suitable for 5-pitch, 9-pitch and other on-load tap changers. Furthermore, it uses a vacuum circuit breaker to achieve arc-free switching, which reduces transformer oil consumption and reduces equipment maintenance costs.

[0035] (5) The control method of the present invention has a high degree of intelligence. It can automatically trigger the switching of the gear and optimize the resistance value of the transition resistor according to the real-time operating conditions such as the voltage fluctuation of the transformer load side and the oil chamber temperature. No manual intervention is required. It is suitable for the complex grid operating conditions of wind power, photovoltaic and other new energy grid connection, meets the power system's needs for flexible adjustment and stable control, effectively improves the grid voltage stability and power quality, and reduces economic losses. Attached Figure Description

[0036] Figure 1 is a schematic diagram of the on-load tap changer device with intelligent adjustment of transition resistance according to the present invention.

[0037] Figure 2 shows the types of intelligent transition resistors in the on-load tap changer device for intelligent adjustment of transition resistors according to the present invention, wherein (a) is a sliding rheostat type and (b) is a multi-resistor series-parallel type.

[0038] Figure 3 is a schematic diagram of the operation of the on-load tap changer with intelligent adjustment of transition resistance according to the present invention;

[0039] Figure 4 is a flowchart of the on-load tap changer operation of the present invention, which features intelligent adjustment of transition resistance. Detailed Implementation

[0040] The invention will now be further described with reference to the accompanying drawings.

[0041] For example Figure 1 Taking the 5-position on-load tap changer shown as an example, the transformer winding taps are 1-5, the intermediate position is 3, the intelligent transition resistor R is connected to the 3-position tap, the initial position is 1, and the target switching position is 3. The device and control method of the present invention are described in detail. The present invention can also be extended to 9-position and other positions of transformer on-load tap changers based on this embodiment.

[0042] Example 1

[0043] like Figure 1 As shown, the on-load tap changer device for intelligent adjustment of transition resistance in this embodiment includes a main circuit, a transition circuit, an intelligent resistance controller K, a voltage sensor, and a temperature sensor; the main circuit is connected to the transformer winding and the neutral point O of the high-voltage end of the transformer; one end of the transition circuit is connected to the intermediate tap of the transformer winding, and the other end is connected to the neutral point O of the high-voltage end of the transformer; the intelligent resistance controller K is electrically connected to the transition circuit.

[0044] The main circuit consists of tap position selector switches K1-K5 connected in sequence and the first vacuum circuit breaker VCB1. The tap position selector switches include tap position selector switches K1-K5 connected in parallel. One end of each tap position selector switch is connected to one of the transformer winding taps 1-5, and the other end converges and is connected to the first vacuum circuit breaker VCB1. The other end of the first vacuum circuit breaker VCB1 is connected to the transformer neutral point O. The main circuit is responsible for switching the transformer on-load tap changer on and off. The number of tap position selector switch groups matches the number of transformer winding taps. Each tap position selector switch is a high-voltage arc-free switch, which can realize smooth switching under power failure conditions.

[0045] The transition circuit consists of a smart transition resistor R and a second vacuum circuit breaker VCB2 connected sequentially. One end of the smart transition resistor R is fixedly connected to the third tap of the transformer winding, and the other end of the second vacuum circuit breaker VCB2 is connected to the neutral point O of the high-voltage end of the transformer. The transition circuit is responsible for switching the transition current during the on-load tap changer switching process. The first vacuum circuit breaker VCB1 and the second vacuum circuit breaker VCB2 are both high-voltage vacuum switches used to switch the working current and transition current of the on-load tap changer, avoiding the generation of electric arcs in the transformer oil, reducing the generation of decomposition gases in the transformer oil, and reducing the rise in oil temperature.

[0046] The intelligent resistor controller K is electrically connected to the intelligent transition resistor R, such as... Figure 2 As shown, the intelligent transition resistor R is a controllable sliding rheostat, such as... Figure 2 (a) or controllable series and parallel resistors, such as Figure 2 (b) When the intelligent transition resistor R is a controllable sliding rheostat, the intelligent resistor controller K is electrically connected to the slider drive mechanism of the controllable sliding rheostat, and adjusts the resistance value by controlling the movement of the slider; when the intelligent transition resistor R is a controllable series-parallel resistor, the intelligent resistor controller K is electrically connected to the branch switches of the controllable series-parallel resistor, and adjusts the resistance value by controlling the on / off state of the branch switches, so that the intelligent transition resistor R matches the optimal resistance value of the current gear switching condition. The intelligent resistor controller K has a built-in multi-objective genetic algorithm module, which is used to calculate the optimal resistance value of the intelligent transition resistor R under different gear switching conditions.

[0047] In this embodiment, the intelligent transition resistor R is a controllable sliding rheostat, and the intelligent resistor controller K is electrically connected to the slider drive mechanism of the controllable sliding rheostat. The resistance value is adjusted by controlling the slider to slide.

[0048] A voltage sensor is installed on the load side of the transformer and is connected to the intelligent resistor controller K via a signal. It is used to detect the voltage waveform on the load side and transmit the voltage signal to the intelligent resistor controller K, providing voltage data for gear switching triggering and optimal resistance value calculation.

[0049] The temperature sensor is installed inside the oil chamber of the on-load tap changer and is connected to the intelligent resistor controller K. It is used to detect the oil chamber temperature and transmit the temperature signal to the intelligent resistor controller K, providing temperature data for the multi-objective genetic algorithm to calculate the optimal resistance value.

[0050] This embodiment only describes the device structure of phase A of the transformer. The device structures of phases B and C are exactly the same as those of phase A, which can realize synchronous voltage regulation control of the three-phase transformer.

[0051] Example 2

[0052] like Figure 3 and Figure 4 As shown, the on-load tap changer control method for intelligently adjusting the transition resistance in this embodiment includes the following steps:

[0053] S1: The voltage waveform on the load side of the transformer is detected by a voltage sensor. When the load voltage fluctuation exceeds the threshold of the gear switching voltage limit, the intelligent resistor controller K calculates the target gear switching position based on the set voltage and triggers the gear switching working signal.

[0054] S2: After receiving the working signal, the intelligent resistor controller K calculates the optimal resistance value of the intelligent transition resistor R under the current working condition based on the multi-objective genetic algorithm, combined with the current initial gear, target gear switching, oil chamber temperature and gear switching transition time, and controls the intelligent transition resistor R to adjust to the optimal resistance value.

[0055] S3: Close the second vacuum circuit breaker VCB2 and connect the transition circuit so that the initial position of the on-load tap changer works in coordination with the transition circuit;

[0056] S4: Disconnect the first vacuum circuit breaker VCB1 to cut off the main circuit, so that the on-load tap changer only operates in the transition circuit;

[0057] S5: Disconnect the gear selection switch corresponding to the initial gear position and close the gear selection switch corresponding to the target gear position to realize gear switching in the power-off state. This gear switching can realize direct switching across gears without the need for sequential switching.

[0058] S6: Close the first vacuum circuit breaker VCB1 and connect it to the main circuit so that the target tap position of the on-load tap changer and the transition circuit work together.

[0059] S7: Disconnect the second vacuum circuit breaker VCB2, cut off the transition circuit, and complete the tap changer switching.

[0060] In step S2, the optimization variables of the multi-objective genetic algorithm are X=(x1, x2, x3)=(R, T, t), where R is the resistance value of the intelligent transition resistor (Ω), T is the room temperature rise of the on-load tap changer oil (°C), and t is the on-load tap changer switch transition time (s). The optimization objectives are min(R), min(T), and min(t), which respectively achieve the goals of reducing resistance loss, ensuring equipment safety and extending insulation life, and reducing power grid fluctuations.

[0061] The specific process of calculating the optimal resistance value based on the multi-objective genetic algorithm in step S2 is as follows:

[0062] S21: Within the inequality constraints of the optimization variables, determine the possible value range of the variables based on practical engineering experience, and use the Latin hypercube sampling method to generate an initial parent population with a total number of N=50.

[0063] S22: Perform selection, crossover, and mutation operations on the initial parent population to generate a new offspring population;

[0064] S23: Merge the new offspring population with the previous generation population, solve for the fitness value of the merged population, and perform non-dominated sorting.

[0065] S24: Calculate the crowding degree of the non-dominated ordination layer and select individuals that meet the conditions to form a new parent population;

[0066] S25: Determine whether the stopping criterion is met. The stopping criterion is that all individuals are in the same level set after non-dominated sorting. If it is met, output the optimal intelligent transition resistor value in the Pareto optimal solution set. The optimal intelligent transition resistor value in the Pareto optimal solution set is the resistance value that meets the actual working conditions of the project in the first non-dominated level. If it is not met, return to step S22.

[0067] The control method of the present invention can realize cross-gear voltage regulation from any initial gear to any target gear, such as switching from gear 1 to gear 2, switching from gear 1 to gear 3, etc., without the need for step-by-step switching, which greatly improves the voltage regulation response speed.

[0068] The following example illustrates the shift from 1st to 3rd gear, including the following steps:

[0069] Step 1: Detect the voltage waveform on the transformer load side using a voltage sensor. When the load voltage fluctuation exceeds the on-load tap changer's switching voltage limit threshold, automatically calculate the target switching tap based on the set voltage. Assume the initial tap is 1 and the target switching tap is 3. Simultaneously, send a working signal to the on-load tap changer's intelligent resistor controller K.

[0070] Step 2: After receiving the working signal, the on-load tap changer intelligent resistor controller K automatically calculates the optimal resistance value of the intelligent transition resistor R under the current operating condition using a multi-objective genetic algorithm, based on the input signal and target range information. Then, it automatically adjusts the intelligent transition resistor R to the optimal resistance value according to the calculation result. The calculation method is as follows:

[0071] 2.1 Selecting Multi-Objective Optimization Variables:

[0072] X=(x1, x2, x3)=(R, T, t)

[0073] Where R (Ω) is the resistance value of the intelligent transition resistor of the on-load tap changer, T (°C) is the room temperature rise of the oil in the on-load tap changer, and t (s) is the transition time for the on-load tap changer to switch positions.

[0074] 2.2 Determine the optimization objective

[0075]

[0076] 2.3 Constraints

[0077] The possible range of values ​​for variables is determined based on practical engineering experience.

[0078] 2.4 Determine the optimization mechanism:

[0079] 2.4.1: Within the constraints of the inequality of the optimization variables, the Latin hypercube sampling method is used to randomly generate an initial parent population of N=50.

[0080] 2.4.2: Selection, crossover, and mutation generate new offspring populations;

[0081] 2.4.3: Merge the offspring population with the previous generation population, solve for the population fitness value, and perform non-dominated sorting;

[0082] 2.4.4: Calculate the crowding degree of the non-dominated ordination layer and select suitable individuals to form a new parent population;

[0083] 2.4.5: Determine the stopping criterion; if satisfied, output the optimal intelligent transition resistance value R; otherwise, return to 4.2.

[0084] 2.5 Determine the stopping criteria:

[0085] To ensure optimal parameter traversal, the stopping criterion is that all individuals, after being sorted by non-dominated order, belong to the same level set. After the algorithm stops, all individuals in the first non-dominated level of the final population are output as the Pareto optimal solution set.

[0086] Step 3: Vacuum circuit breaker VCB2 closes, and the transition circuit is connected. At this time, the on-load tap changer operates in position 1 and the transition circuit works together.

[0087] Step 4: The vacuum circuit breaker VCB1 is disconnected, the main circuit is cut off, and the on-load tap changer of the transformer is in the transition circuit.

[0088] Step 5: Switch K1 is open, and switch K3 is closed. At this time, the working position of the switch in the power-off state changes from position 1 to position 3.

[0089] Step 6: Vacuum circuit breaker VCB1 closes, connecting to the main circuit. At this time, the on-load tap changer operates in position 3 and the transition circuit works together.

[0090] Step 7: Vacuum circuit breaker VCB2 is disconnected, and the transition circuit is cut off. At this time, the on-load tap changer of the transformer is operating in position 3, and the tap change is completed.

[0091] This invention proposes an intelligent on-load tap changer device and control method for adjusting the transition resistance. It can automatically adjust the resistance value R of the intelligent transition resistance of the transformer on-load tap changer according to the real-time operating conditions such as load-side voltage fluctuations and on-load tap changer oil chamber temperature. It can realize cross-taper voltage regulation, reduce voltage fluctuations and losses during tap switching, accelerate the transformer load voltage fluctuation response speed, further improve the grid voltage stability, improve power quality, and reduce economic losses.

Claims

1. An on-load tap changer device with intelligent adjustable transition resistance, characterized in that, It includes a main circuit, a transition circuit, and an intelligent resistor controller. The main circuit is connected to the transformer winding and the neutral point of the transformer high-voltage end. One end of the transition circuit is connected to the intermediate tap of the transformer winding, and the other end is connected to the neutral point of the transformer high-voltage end. The intelligent resistor controller is electrically connected to the transition circuit. The main circuit includes a gear selection switch group and a first vacuum circuit breaker connected in sequence. The gear selection switch group includes several gear selection switches connected in parallel. One end of each gear selection switch is connected to a different tap of the transformer winding, and the other end is connected to one end of the first vacuum circuit breaker. The other end of the first vacuum circuit breaker is connected to the neutral point of the high-voltage side of the transformer. The transition circuit includes an intelligent transition resistor and a second vacuum circuit breaker connected in sequence. One end of the intelligent transition resistor is connected to the intermediate tap of the transformer winding, and the other end of the second vacuum circuit breaker is connected to the neutral point of the high-voltage end of the transformer. The intelligent resistor controller is electrically connected to the intelligent transition resistor and is used to control the resistance adjustment of the intelligent transition resistor. The intelligent resistor controller has a built-in multi-objective genetic algorithm module for calculating the optimal resistance value of the intelligent transition resistor under different gear switching conditions.

2. The on-load tap changer with intelligent adjustable transition resistance according to claim 1, characterized in that, The number of gear selection switching groups matches the number of transformer winding taps. There are at least five transformer winding taps, and each gear selection switching group is a high-voltage arc-free switching switch.

3. The on-load tap changer with intelligent adjustable transition resistance according to claim 1, characterized in that, Both the first and second vacuum circuit breakers are high-voltage vacuum switches used to switch on and off the operating current and transition current of the on-load tap changer.

4. The on-load tap changer with intelligent adjustable transition resistance according to claim 1, characterized in that, The intelligent transition resistor is a controllable sliding rheostat or a controllable series-parallel resistor. When the intelligent transition resistor is a controllable sliding rheostat, the intelligent resistor controller is electrically connected to the slider drive mechanism of the controllable sliding rheostat, and the resistance value is adjusted by controlling the movement of the slider. When the intelligent transition resistor is a controllable series-parallel resistor, the intelligent resistor controller is electrically connected to the branch switches of the controllable series-parallel resistor, and the resistance value is adjusted by controlling the opening and closing of the branch switches.

5. The on-load tap changer with intelligent adjustable transition resistance according to claim 1, characterized in that, It also includes a voltage sensor, which is installed on the load side of the transformer and connected to the intelligent resistor controller for detecting the voltage waveform on the load side of the transformer and transmitting the voltage signal to the intelligent resistor controller.

6. The on-load tap changer with intelligent adjustable transition resistance according to claim 5, characterized in that, It also includes a temperature sensor, which is installed inside the oil chamber of the on-load tap changer and is connected to the intelligent resistor controller for detecting the oil chamber temperature and transmitting the temperature signal to the intelligent resistor controller.

7. A method for controlling an on-load tap changer with intelligent adjustment of transition resistance based on the device described in any one of claims 1-6, characterized in that, Includes the following steps: S1: The voltage waveform on the load side of the transformer is detected by a voltage sensor. When the load voltage fluctuation exceeds the threshold of the gear switching voltage limit, the intelligent resistor controller calculates the target gear switching according to the set voltage and triggers the gear switching working signal. S2: After receiving the working signal, the intelligent resistor controller calculates the optimal resistance value of the intelligent transition resistor under the current working condition based on the multi-objective genetic algorithm, combined with the current initial gear, target switching gear, oil chamber temperature and gear switching transition time, and controls the intelligent transition resistor to adjust to the optimal resistance value. S3: Close the second vacuum circuit breaker and connect the transition circuit so that the initial position of the on-load tap changer works in coordination with the transition circuit; S4: Disconnect the first vacuum circuit breaker, cut off the main circuit, and make the on-load tap changer only operate in the transition circuit; S5: Disconnect the gear selection switch corresponding to the initial gear position and close the gear selection switch corresponding to the target gear position to achieve gear switching in the power-off state; S6: Close the first vacuum circuit breaker and connect to the main circuit, so that the target tap position of the on-load tap changer and the transition circuit work together; S7: Disconnect the second vacuum circuit breaker, cut off the transition circuit, and complete the tap changer switching.

8. The on-load tap changer control method for intelligently adjusting transition resistance according to claim 7, characterized in that, The optimization variables of the multi-objective genetic algorithm in step S2 are X=(x1, x2, x3)=(R, T, t), where R is the resistance value of the intelligent transition resistor, T is the room temperature rise of the on-load tap changer oil, and t is the on-load tap changer gear switching transition time; the optimization objectives are: min(R), min(T), min(t).

9. The on-load tap changer control method for intelligently adjusting transition resistance according to claim 8, characterized in that, The specific process of calculating the optimal resistance value based on the multi-objective genetic algorithm in step S2 is as follows: S21: Within the inequality constraints of the optimization variables, the initial parent population is generated using the Latin hypercube sampling method. S22: Perform selection, crossover, and mutation operations on the initial parent population to generate a new offspring population; S23: Merge the new offspring population with the previous generation population, solve for the fitness value of the merged population, and perform non-dominated sorting. S24: Calculate the crowding degree of the non-dominated ordination layer and select individuals that meet the conditions to form a new parent population; S25: Determine whether the stopping criterion is met. If it is met, output the optimal smart transition resistor value in the Pareto optimal solution set; otherwise, return to step S22.

10. The on-load tap changer control method for intelligently adjusting transition resistance according to claim 9, characterized in that, The stopping criterion in step S25 is: all individuals are in the same level set after non-dominated sorting; the optimal intelligent transition resistor value in the Pareto optimal solution set is the resistance value that satisfies the actual working conditions of the project in the first non-dominated level.

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