SF6 circuit breaker phase selection closing stability improving method considering multi-factor coupling

Abstract

The invention discloses an SF6 circuit breaker phase selection closing stability improvement method considering multi-factor coupling, and the method comprises the steps: obtaining a closing time prediction amount under the influence of an oil pressure operation voltage of a hydraulic mechanism in an environment temperature circuit breaker through a sample circuit breaker closing displacement curve in a multi-factor coupling database which is built through a circuit breaker closing displacement curve; compared with the prior art that prediction on the closing time by only considering a single factor variable after decoupling is closer to the actual closing action time of the circuit breaker, compensation on the closing time of the operating mechanism can be effectively completed, and the overall phase selection closing time can be obtained by considering the action closing time influenced by pre-breakdown and compensating the closing time of the circuit breaker. In the field of ultra-high voltage larger than 550kV, the phase selection closing stability of the circuit breaker is improved, and the operation reliability of a power supply system is further improved.

Description

Technical Field

[0001] The present invention relates to the field of intelligent control of high-voltage electrical equipment, and in particular to a method for improving the phase selection and closing stability of an SF6 circuit breaker taking into account multi-factor coupling. Background Art

[0002] As an indispensable key equipment in the power system, the circuit breaker undertakes the important task of controlling and protecting the safe operation of the power grid. As the modern power system develops towards higher voltage levels and larger capacities, circuit breakers that use SF6 gas as insulation and arc extinguishing medium have been widely used in power systems. SF6 circuit breakers have the advantages of high breaking voltage, strong breaking capacity, more continuous breaking times, and low noise. Therefore, the stability requirements for high-voltage SF6 circuit breakers are also increasing.

[0003] In high-voltage systems, circuit breakers need to be frequently switched on and off. In order to reduce the impact of overvoltage and high-frequency surge current on the circuit breaker itself and the power grid system, the circuit breaker is closed at the voltage zero point. Generally, an intelligent control device is added to make the circuit breaker open and close at the target phase angle. A basic premise of phase selection closing technology is the stability of the circuit breaker operation. Due to the particularity of the phase selection closing device, it is widely used in the medium and low voltage fields, but in the ultra-high voltage field greater than 550kV, due to the complex structure of the ultra-high voltage circuit breaker, the poor stability of the transmission system, and the low reliability of the mechanism, the stability of the ultra-high voltage circuit breaker is more difficult to control than that of the medium and low voltage circuit breaker.

[0004] At present, the method of improving the stability of circuit breakers mainly relies on algorithms to analyze and predict historical data, and compensate through single factors such as temperature and static time. However, the existing technology is relatively single in considering data factors when predicting the phase selection closing time, and usually fails to systematically consider the influence of single factors after decoupling, and simultaneously analyze the changes in action stability under the influence of multiple factors. Summary of the invention

[0005] The present invention discloses a method for improving the phase selection and closing stability of an SF6 circuit breaker taking into account the coupling of multiple factors, so as to overcome the above technical problems.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A method for improving the phase selection and closing stability of SF6 circuit breaker taking into account multi-factor coupling comprises the following steps:

[0008] S1: Obtain the closing displacement of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, the air pressure of the arc extinguishing chamber of the circuit breaker, and the ambient temperature of the environment where the circuit breaker is located;

[0009] S2: according to the closing displacement of the circuit breaker, the ambient temperature, the air pressure of the arc extinguishing chamber of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, and the operating voltage, based on the mechanical characteristics test of the circuit breaker, the closing displacement curve of the circuit breaker is obtained, and the closing displacement curve of the circuit breaker is added to the multi-factor coupling database;

[0010] S3: According to the circuit breaker closing displacement curve in the multi-factor coupling database, based on the intelligent phase selection algorithm, the closing time prediction under the influence of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage is obtained;

[0011] S4: Obtaining the phase selection closing time according to the predicted amount of closing time under the influence of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage;

[0012] S5: According to the phase selection closing time, the action closing time considering the influence of pre-breakdown is obtained;

[0013] S6: According to the action closing time considering the influence of pre-breakdown, the total phase selection closing time is obtained. Further, in S4, the formula used to obtain the phase selection closing time is as follows:

[0014] t=σ1t1(τ,p,U)±σ2Δt2(P)

[0015] In the formula: t is the phase selection closing time; σ1 is the comprehensive compensation coefficient of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage; t1(τ, p, U) is the predicted closing time obtained by the intelligent phase selection algorithm under the influence of ambient temperature τ, energy storage oil pressure p, and operating voltage U; τ is the ambient temperature; p is the energy storage oil pressure, that is, the oil pressure of the hydraulic mechanism in the circuit breaker; U is the operating voltage; σ2 is the compensation coefficient of the air pressure factor of the circuit breaker arc extinguishing chamber; Δt2(P) is the change in closing time caused by the air pressure in the circuit breaker arc extinguishing chamber; P is the air pressure in the circuit breaker arc extinguishing chamber.

[0016] Furthermore, in S5, the formula used to obtain the action closing time considering the influence of pre-breakdown is as follows:

[0017] t′=t+Δt3=σ1t1(τ,p,U)±σ2Δt2(P)+Δt3

[0018] Among them, Δt3 is the change of closing time considering the influence of pre-breakdown; t′ is the action closing time considering the influence of pre-breakdown; and t is the phase selection closing time.

[0019] Furthermore, in S6, the formula used to obtain the total phase selection closing time is as follows:

[0020] t″=t′+Δt4=σ1t1(τ, p, U)±σ2Δt2(P)+Δt3+Δt4

[0021] in,

[0022] Δt4=ω(t la,for -t la,ope )

[0023] Where: t″ is the total phase selection closing time; Δt4 is the weighted action time compensation; ω is the weighting coefficient, 0<ω<1; t la,for is the target closing time; t la,ope is the actual phase selection and closing time of the last circuit breaker; t′ is the action closing time considering the influence of pre-breakdown.

[0024] Furthermore, the intelligent phase selection algorithm is any one of a neural network algorithm, a deep learning algorithm or a support vector machine algorithm based on historical data.

[0025] Beneficial effect: The method for improving the phase selection and closing stability of SF6 circuit breakers taking into account multi-factor coupling of the present invention obtains the predicted closing time under the influence of the oil pressure operating voltage of the hydraulic mechanism in the circuit breaker at ambient temperature through the sample circuit breaker closing displacement curve in the multi-factor coupling database established by the circuit breaker closing displacement curve, and compensates for the circuit breaker closing time by considering the action closing time affected by the pre-breakdown effect, so as to obtain the total phase selection and closing time. Compared with the existing method of predicting the closing time by only considering the single factor variable after decoupling, the present invention is closer to the actual circuit breaker closing action time and can effectively complete the compensation of the closing time of the operating mechanism. In the ultra-high voltage field greater than 550kV, the phase selection and closing stability of the circuit breaker is improved, thereby improving the reliability of the power supply system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 It is a flow chart of the method for improving the phase selection and closing stability of a circuit breaker of the present invention;

[0028] Figure 2 2 is a schematic diagram of the structure of a hydraulic mechanism of a phase-selective closing circuit breaker according to an embodiment of the present invention;

[0029] Figure 3 is a curve showing the influence of air pressure on the closing time of an embodiment of the present invention;

[0030] Figure 4 is a schematic diagram of the results of a multi-factor coupling test according to an embodiment of the present invention;

[0031] Figure 5 is a schematic diagram of comparison results of different compensation methods used in an embodiment of the present invention;

[0032] Figure 6 is a schematic diagram of a phase selection and closing process according to an embodiment of the present invention;

[0033] Figure 7 It is a process topology diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] This embodiment introduces a method for improving the phase selection and closing stability of SF6 circuit breaker taking into account the coupling of multiple factors, such as Figure 1 and Figure 7 As shown, the following steps are included:

[0036] S1: Obtain the closing displacement of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, the air pressure of the arc extinguishing chamber of the circuit breaker, and the ambient temperature of the environment where the circuit breaker is located;

[0037] Specifically, in this embodiment, a temperature sensor, a displacement sensor, a hydraulic sensor, a Hall sensor, and an air pressure sensor are set in the hydraulic mechanism device of the circuit breaker, and an air pressure sensor is set at the cylinder of the arc extinguishing chamber, and a 4-20mA signal is output to access the control system. The ambient temperature of the environment where the circuit breaker is located is obtained through the temperature sensor, and the closing displacement of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, the closing current of the circuit breaker, and the air pressure of the arc extinguishing chamber of the circuit breaker are respectively monitored through the displacement sensor, the hydraulic sensor, the Hall sensor, and the air pressure sensor. At the same time, this embodiment also collects the mechanical characteristics of the circuit breaker closing, obtains the actual phase selection closing time of the circuit breaker, and collects the electrical characteristics of the circuit breaker closing to obtain the closing current of the circuit breaker.

[0038] S2: according to the closing displacement of the circuit breaker, the ambient temperature, the air pressure of the arc extinguishing chamber of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, and the operating voltage, based on the mechanical characteristics test of the circuit breaker, the closing displacement curve of the circuit breaker is obtained, and the closing displacement curve of the circuit breaker is added to the multi-factor coupling database;

[0039] Specifically, in this embodiment, the ambient temperature, the air pressure of the arc extinguishing chamber of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, the operating voltage, etc. are used as coupling influencing factors to implement the circuit breaker mechanical characteristics test and obtain the circuit breaker closing displacement curve. Among them, the circuit breaker mechanical characteristics test is a conventional technology in the field, and the test method is not described in detail here.

[0040] Specifically, according to the multiple circuit breaker closing displacement curves in the multi-factor coupling database, the nonlinear action law of the circuit breaker phase selection closing time can be learned. Generally speaking, the higher the ambient temperature, the closer the energy storage oil pressure is to the rated oil pressure, and the higher the operating voltage, the faster the circuit breaker closing time is, and data correction can be achieved;

[0041] S3: According to the circuit breaker closing displacement curve in the multi-factor coupling database, based on the intelligent phase selection algorithm, the closing time prediction under the influence of the ambient temperature τ, the oil pressure p of the hydraulic mechanism in the circuit breaker, and the operating voltage U is obtained;

[0042] Specifically, in this embodiment, a conventional intelligent phase selection algorithm is used, combined with multiple circuit breaker closing displacement curves in a multi-factor coupling database, to obtain the predicted closing time under the influence of ambient temperature τ, oil pressure p of the hydraulic mechanism in the circuit breaker, and operating voltage U, and the closing time of the phase-selected circuit breaker is predicted and compensated, such as by using regression analysis based on historical data, machine learning, or expert systems.

[0043] S4: Obtain the phase selection closing time according to the predicted amount of closing time under the influence of ambient temperature τ, oil pressure p of the hydraulic mechanism in the circuit breaker, and operating voltage U;

[0044] Preferably, the formula used to obtain the phase selection closing time is as follows:

[0045] t=σ1t1(τ,p,U)±σ2Δt2(P)

[0046] Where: t is the phase selection closing time; σ1 is the comprehensive compensation coefficient of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage; t1(τ, p, U) is the predicted closing time obtained by the intelligent phase selection algorithm under the influence of ambient temperature τ, energy storage oil pressure p, and operating voltage U; τ is the ambient temperature; p is the energy storage oil pressure, that is, the oil pressure of the hydraulic mechanism in the circuit breaker; U is the operating voltage; σ2 is the compensation coefficient of the air pressure factor of the circuit breaker arc extinguishing chamber; Δt2(P) is the change in closing time caused by the air pressure in the circuit breaker arc extinguishing chamber; P is the air pressure in the circuit breaker arc extinguishing chamber;

[0047] Specifically, the factors affecting the phase selection and closing stability of the circuit breaker in this embodiment include main influencing factors and secondary influencing factors, wherein the main influencing factors include the ambient temperature τ, the oil pressure p of the hydraulic mechanism in the circuit breaker, and the operating voltage U, and the secondary factor is the air pressure in the arc extinguishing chamber of the circuit breaker.

[0048] S5: According to the phase selection closing time, the action closing time considering the influence of pre-breakdown is obtained;

[0049] Specifically, this embodiment considers the influence of pre-breakdown on closing time, compensates closing time, and directly superimposes the compensation amount of phase selection closing time to obtain the action closing time:

[0050] t′=t+Δt3=σ1t1(τ,p,U)±σ2Δt2(P)+Δt3

[0051] Among them, Δt3 is the change of closing time considering the influence of pre-breakdown; t′ is the action closing time considering the influence of pre-breakdown.

[0052] S6: Obtaining a total phase selection closing time according to the action closing time considering the influence of pre-breakdown;

[0053] Preferably, in S6, the formula used to obtain the total phase selection closing time is as follows:

[0054] t″=t′+Δt4=σ1t1(τ, p, U)±σ2Δt2(P)+Δt3+Δt4

[0055] in,

[0056] Δt4=ω(t la,for -t la,ope )

[0057] Where: t″ is the total phase selection closing time; Δt4 is the weighted action time compensation; ω is the weighting coefficient, 0<ω<1; t la,for is the target closing time; t la,ope The actual phase selection and closing time of the last circuit breaker;

[0058] Specifically, this embodiment uses the ambient temperature, the air pressure in the arc extinguishing chamber of the circuit breaker, the energy storage oil pressure (the oil pressure of the hydraulic mechanism in the circuit breaker) and the operating voltage obtained in real time as the input of the intelligent phase selection algorithm to obtain the circuit breaker closing displacement curve, and then obtain the total phase selection closing time predicted under the current conditions.

[0059] Specifically, the weighting coefficient ω is mainly used to control the adjustment range of the compensation amount to prevent the system from overcorrecting or oscillating due to a single error that is too large. It reflects the sensitivity of the compensation to historical errors. The closer ω is to 1, the larger the weighted action time compensation Δt4 is, and the more sensitive the system is to the adjustment of the last prediction error, but it may cause large fluctuations. The smaller ω is, the smaller the weighted action time compensation Δt4 is, and the system is more gentle in adjusting the historical error and responding more smoothly, but the convergence speed may be slower. This embodiment can avoid directly using the error t la,for -t la,ope Compensation may result in over-adjustment or instability.

[0060] Specifically, the phase-selective closing circuit breaker equipped with a hydraulic mechanism adapted in this embodiment has a structure as follows: Figure 2 As shown, it consists of four parts: energy storage element 1 (motor, oil pump, energy accumulator), control element 2 (electromagnet, valve system), actuator 3 (working cylinder) and auxiliary element 4 (oil tank, pressure switch, pipeline). When storing energy, the motor drives the oil pump to pump the oil in the oil tank into the energy accumulator for energy storage; when closing, the closing electromagnet is energized, and under the action of electromagnetic force, the closing electromagnet pushes the valve core of the closing pilot valve to move, the valve port opens, and the closing amplification valve is driven to move, changing the control chamber pressure to drive the main valve to move, thereby changing the rodless chamber pressure of the working cylinder to high pressure, and pushing the working cylinder to close. Considering the stability of the phase-selective closing circuit breaker, it is mainly necessary to monitor its mechanical and electrical characteristics.

[0061] Specifically, this embodiment uses sensors to collect real-time SF6 arc chamber pressure, energy storage oil pressure, operating voltage and ambient temperature, and simultaneously measures the circuit breaker closing time. The influence of SF6 arc chamber pressure is studied as follows: a mechanical property test of a 550kV phase-selective circuit breaker is carried out. Figure 3 Analysis of the closing time variation curve shows that under the same oil pressure, operating voltage and temperature conditions, the maximum closing time deviation is 0.68ms in the range of 0.5Mpa to 0.7Mpa, which is classified as a secondary influencing factor of the closing stability of the phase-selective circuit breaker.

[0062] Specifically, in this embodiment, the influence of energy storage oil pressure is studied as follows: a mechanical property test of a 550kV phase-selective circuit breaker is carried out. Under the same air pressure, operating voltage and temperature conditions, the maximum closing time deviation is 4.17ms in the range of 47Mpa to 55Mpa, which is classified as the main influencing factor of the closing stability of the phase-selective circuit breaker.

[0063] Specifically, in this embodiment, the influence of operating voltage is studied as follows: a mechanical characteristic test of a 550kV phase-selective circuit breaker is carried out. Under the same gas pressure, energy storage oil pressure and temperature conditions, within the range of 85% to 100% of the rated operating voltage of the mechanism, the closing time deviation decreases with the increase of the operating voltage, and the closing time offset change rate is less than 0.3ms; within the range of 100% to 110% of the rated operating voltage, the closing time deviation increases with the increase of voltage, and the closing time offset change rate is less than 0.3ms. When the circuit breaker is operated at rated or high voltage, the mechanical stability is good. It is classified as a secondary influencing factor of the closing stability of the phase-selective circuit breaker.

[0064] Specifically, in this embodiment, the study of the influence of ambient temperature is as follows: a mechanical property test (-40℃~40℃) of a 550kV phase-selective circuit breaker is carried out. Under the same gas pressure, energy storage oil pressure and operating voltage conditions, the closing time shows a change law that decreases with increasing temperature. The maximum closing time deviation of the low temperature test is 6.74ms, and the maximum closing time deviation of the high temperature test is 0.5ms. It can be seen that the influence of temperature on the closing time, that is, the action stability of the hydraulic mechanism, has the greatest influence, which is classified as the main influencing factor of the closing stability of the phase-selective circuit breaker, and the closing time compensation is performed.

[0065] Specifically, in this embodiment, the coupling influencing factor test is carried out as follows: a coupling influencing factor test is carried out for 550kV SF6, and the coupling influence of ambient temperature, energy storage oil pressure, and voltage on the stability of closing action is comprehensively considered. Figure 4 According to the coupling test results, temperature has the greatest impact on the operation of the circuit breaker. The higher the temperature, the faster the operation. The closer the oil pressure is to the rated oil pressure and rated voltage, the better the stability of the closing action.

[0066] Specifically, the above test results can be used to evaluate the dispersion of high-voltage circuit breaker operation, and can also be used to predict the circuit breaker operation time when a single influencing factor changes. In addition, the test in this embodiment takes into account multiple influencing factor variables, which can effectively provide a data basis for subsequent compensation plans.

[0067] Specifically, the traditional feedforward compensation of phase selection and closing generally only considers the influence of one or several single variable influencing factors after decoupling, and generally performs linear fitting, such as Figure 5 The factor decoupling compensation and factor coupling compensation methods are used to compensate for the temperature of -5°C, the energy storage oil pressure of 50Mpa, and the test voltage of 90% of the rated operating voltage, i.e., 198V. The traditional decoupling compensation uses linear fitting to compensate the temperature to 20°C, the oil pressure to 55Mpa, and the test voltage to the rated voltage, and then linearly superimposes the weight ratio. The compensation results are as follows: Figure 6 The blue curve; the compensation results considering the coupling factor and the intelligent phase selection algorithm are as follows Figure 6From the green curve, it can be seen that the result of using the intelligent phase selection and closing algorithm and coupling factor compensation of this embodiment is closer to the actual test curve.

[0068] Specifically, in this embodiment, the influence of closing pre-breakdown characteristics is studied as follows: for high-voltage SF6 circuit breakers, a pre-breakdown test is conducted, and the dynamic breakdown voltage of the SF6 gas in the contact gap of the circuit breaker during the closing operation is obtained by collecting the voltage at both ends of the circuit breaker break. When the target phase is the voltage peak point, the pre-breakdown influence is the greatest, and compensation is required to improve the operation stability.

[0069] Specifically, in this embodiment, data fitting and correction are performed as follows: Through analysis, it can be known that there is coupling between various factors, and the factor coupling test study is fitted to form a database, obtain the action rules, and realize data correction.

[0070] In this embodiment, the phase selection closing process of the phase selection circuit breaker closing time prediction and compensation is as follows: Figure 6 As shown in the figure, the closing time of the phase-selected circuit breaker is predicted and compensated by using the intelligent phase selection algorithm (neural network algorithm) combined with the fitting database. The compensation coefficients of the main influencing factors including temperature, energy storage oil pressure, and air pressure are set to compensate for them; the compensation coefficients of the secondary influencing factors are set. In summary, the closing time of the hydraulic mechanism SF6 circuit breaker can be superimposed as:

[0071] t=σ1t1(τ,p,U)±σ2Δt2(P)

[0072] And considering the influence of pre-breakdown, the closing time is compensated. This condition is not within the scope of intelligent algorithm training. The compensation amount is directly superimposed to obtain the action closing time:

[0073] t′=t+Δt3=σ1t1(τ,p,U)±σ2Δt2(P)+Δt3

[0074] The ambient temperature, air pressure, energy storage oil pressure and operating voltage measured in real time are used as the input of the intelligent phase selection algorithm, which outputs the predicted closing action time under the current conditions. By comparing the closing time of the hydraulic mechanism with the target time, the compensation amount for the next action time is:

[0075] Δt4=ω(t la,for -t la,ope )

[0076] The total phase selection closing time is:

[0077] t″=t′+Δt4=σ1t1(τ, p, U)±σ2Δt2(P)+Δt3+Δt4.

[0078] In summary, this embodiment combines a large amount of single influencing factor and multiple coupling factor test data with an intelligent phase selection algorithm (neural network algorithm) to perform fitting, form a database, realize data correction, and compensate for the circuit breaker action time, effectively improving the SF6 circuit breaker phase selection and closing accuracy, reducing the dispersion of phase selection circuit breaker closing, and improving the phase selection accuracy and action stability.

[0079] This embodiment covers the collection and compensation of mechanical and electrical characteristics of the circuit breaker, which can effectively suppress the inrush current and overvoltage generated during phase selection and switching, and improve the operational stability of the circuit breaker and the system. Taking into account the existing research basis and the analysis of the field simulation test of the circuit breaker, a comprehensive stability improvement method is proposed that takes into account the influence of SF6 gas pressure, operating voltage, energy storage oil pressure, temperature and pre-breakdown on the stability of the SF6 circuit breaker. Compared with the existing prediction of the closing time by only considering the single factor variable after decoupling, this embodiment is closer to the actual closing action time of the circuit breaker. After compensation, there is still a deviation from the actual coupling test. The present invention adopts multiple fitting of empirical data and simulation, and the accuracy of the feedforward compensation can be improved by 10% compared with the existing research. It can effectively complete the compensation of the closing time of the operating mechanism, improve the phase selection and closing stability of the circuit breaker, and thus improve the reliability of the power supply system operation.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the phase selection and closing stability of SF6 circuit breakers taking into account multi-factor coupling, characterized in that: The steps include: S1: Obtain the closing displacement of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, the air pressure of the arc extinguishing chamber of the circuit breaker, and the ambient temperature of the environment where the circuit breaker is located; S2: according to the closing displacement of the circuit breaker, the ambient temperature, the air pressure of the arc extinguishing chamber of the circuit breaker, the oil pressure of the hydraulic mechanism in the circuit breaker, and the operating voltage, based on the mechanical characteristics test of the circuit breaker, the closing displacement curve of the circuit breaker is obtained, and the closing displacement curve of the circuit breaker is added to the multi-factor coupling database; S3: According to the circuit breaker closing displacement curve in the multi-factor coupling database, based on the intelligent phase selection algorithm, the closing time prediction under the influence of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage is obtained; S4: Obtaining the phase selection closing time according to the predicted amount of closing time under the influence of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage; S5: According to the phase selection closing time, an action closing time considering the influence of pre-breakdown is obtained; S6: According to the action closing time considering the influence of pre-breakdown, the total phase selection closing time is obtained.

2. A method for improving the phase selection and closing stability of SF6 circuit breaker taking into account multi-factor coupling according to claim 1, characterized in that: In S4, the formula used to obtain the phase selection closing time is as follows: t=σ1t1(τ,p,U)±σ2Δt2(P) In the formula: t is the phase selection closing time; σ1 is the comprehensive compensation coefficient of ambient temperature, oil pressure of the hydraulic mechanism in the circuit breaker, and operating voltage; t1(τ, p, U) is the predicted closing time obtained by the intelligent phase selection algorithm under the influence of ambient temperature τ, energy storage oil pressure p, and operating voltage U; τ is the ambient temperature; p is the energy storage oil pressure, that is, the oil pressure of the hydraulic mechanism in the circuit breaker; U is the operating voltage; σ2 is the compensation coefficient of the air pressure factor of the circuit breaker arc extinguishing chamber; Δt2(P) is the change in closing time caused by the air pressure in the circuit breaker arc extinguishing chamber; P is the air pressure in the circuit breaker arc extinguishing chamber.

3. A method for improving the phase selection and closing stability of SF6 circuit breaker taking into account multi-factor coupling according to claim 1, characterized in that: In S5, the formula used to obtain the action closing time considering the influence of pre-breakdown is as follows: t′=t+Δt3=σ1t1(τ,p,U)±σ2Δt2(P)+Δt3 Among them, Δt3 is the change of closing time considering the influence of pre-breakdown; t′ is the action closing time considering the influence of pre-breakdown; t is the phase selection closing time.

4. A method for improving the phase selection and closing stability of SF6 circuit breaker taking into account multi-factor coupling according to claim 1, characterized in that: In S6, the formula used to obtain the total phase selection closing time is as follows: t″=t′+Δt4=σ1t1(τ, p, U)±σ2Δt2(P)+Δt3+Δt4 in, Δt4=ω(t la,for -t la,ope ) Where: t″ is the total phase selection closing time; Δt4 is the weighted action time compensation; ω is the weighting coefficient, 0<ω<1; t la,for is the target closing time; t la,ope is the actual phase selection and closing time of the last circuit breaker; t′ is the action closing time considering the influence of pre-breakdown.

5. A method for improving the phase selection and closing stability of SF6 circuit breaker taking into account multi-factor coupling according to claim 1, characterized in that: The intelligent phase selection algorithm is any one of a neural network algorithm, a deep learning algorithm or a support vector machine algorithm based on historical data.

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