Power grid equipment non-power-off emergency air supply method

Abstract

The invention discloses a power grid equipment uninterruptible emergency gas supply method, which comprises the following steps of: firstly, measuring an initial mixing ratio and an initial pressure value of mixed gas formed by SF6 gas and nitrogen in electrical equipment in a power grid, and then combining a preset target mixing ratio and a target pressure value of the mixed gas in the electrical equipment; respectively calculating the gas supplementing amount of the SF6 gas and the gas supplementing amount of the nitrogen, reflecting through the real-time pressure value of the mixed gas in the electrical equipment, sequentially supplementing the SF6 gas and the nitrogen into the electrical equipment, and supplementing the SF6 gas until the real-time pressure value of the mixed gas reaches the pressure value corresponding to the corresponding gas supplementing amount of the SF6 gas; the nitrogen is supplemented until the real-time pressure value of the mixed gas reaches the target pressure value, and finally, the current mixing ratio of the mixed gas in the electrical equipment is measured again to ensure that the proportion of the SF6 gas in the mixed gas exceeds the proportion of the SF6 gas in the target mixing ratio, so that the mixed gas of the SF6 gas and the nitrogen in the electrical equipment is automatically supplemented without power failure, and the safety of the electrical equipment is improved. And safe operation of equipment in a power grid is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical equipment and relates to a method for replenishing gas for power grid equipment, in particular to a method for replenishing gas for power grid equipment without power outage. Background Art

[0002] At present, SF6 gas is widely used in power systems, mainly in high-voltage circuit breakers and GIS combined electrical equipment. Circuit breakers are used for breaking and arc extinguishing during operation. Since SF6 gas has a high capacity in current breaking and arc extinguishing in electrical equipment, the remaining gas chambers mainly play an insulating role. According to the requirements of environmental protection and greenhouse gas emissions, new products and new energy combinations are used to reduce the use of SF6 gas. SF6 gas and nitrogen mixed gas are specially selected for use, which can improve green environmental protection and meet national requirements to enhance environmental protection awareness.

[0003] At present, SF6 gas is used in busbars, lightning arresters, voltage transformers, current transformers and cable outlets in GIS equipment, which requires a large amount of gas. Various tests have shown that GIS busbar gas chambers can use 30% SF6 gas mixed with 70% nitrogen to form a mixed gas, which can reduce the use of a large amount of SF6 gas overall. The use of mixed gas can not only ensure the normal operation of the equipment, but also reduce the pollution to the atmosphere, improve the stable operation of the equipment and the environmental protection effect.

[0004] However, during the operation of the power grid, due to various reasons, the mixed gas in the electrical equipment is prone to leakage, affecting the safe use of the electrical equipment. In addition, the power grid cannot be shut down for maintenance during many major events. Therefore, a method is needed that can automatically replenish gas according to the pressure changes inside the electrical equipment without shutting down the power grid to ensure the safe operation of the equipment in the power grid. Summary of the invention

[0005] In order to solve the technical problems existing in the background technology, the present invention proposes an emergency gas replenishment method for power grid equipment without power outage, which realizes the automatic gas replenishment of the mixed gas of SF6 gas and nitrogen in the electrical equipment without power outage, ensuring the safe operation of the equipment in the power grid.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for emergency gas replenishment of power grid equipment without power outage comprises the following steps:

[0008] Measure the initial pressure value of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment in the power grid;

[0009] When the initial pressure value of the mixed gas inside the electrical equipment is less than the preset pressure threshold, the replenishment amounts of SF6 gas and nitrogen are calculated respectively according to the preset target mixing ratio and target pressure value of the mixed gas inside the electrical equipment, and SF6 gas and nitrogen are replenished into the electrical equipment in turn.

[0010] Furthermore, the calculation of the replenishment amount of SF6 gas and nitrogen specifically includes the following steps:

[0011] Calculate the total gas replenishment volume of SF6 gas and nitrogen based on the difference between the initial pressure value and the target pressure value of the mixed gas inside the electrical equipment;

[0012] According to the target mixing ratio of the mixed gas inside the electrical equipment, the gas replenishment ratio of SF6 gas and nitrogen in the total gas replenishment amount of SF6 gas and nitrogen is calculated to obtain the gas replenishment amounts of SF6 gas and nitrogen respectively.

[0013] Furthermore, the replenishment amount of SF6 gas and nitrogen is reflected by the real-time pressure value of the mixed gas inside the electrical equipment. The pressure difference between the initial pressure value and the target pressure value of the mixed gas inside the electrical equipment is divided into a first pressure interval and a second pressure interval according to the replenishment ratio of SF6 gas and nitrogen. The first pressure interval is from the first pressure value p1 to the second pressure value p2, and the second pressure interval is from the second pressure value p2 to the third pressure value p3. SF6 gas is replenished into the electrical equipment until the real-time pressure value of the mixed gas inside the electrical equipment reaches the second pressure value p2, and then nitrogen is replenished into the electrical equipment until the real-time pressure value of the mixed gas inside the electrical equipment reaches the third pressure value p3. The first pressure value p1 is the initial pressure value of the mixed gas inside the electrical equipment, and the third pressure value p3 is the target pressure value of the mixed gas inside the electrical equipment.

[0014] Furthermore, before “measuring the pressure value of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment in the power grid”, it also includes:

[0015] Measure the initial mixing ratio of SF6 gas and nitrogen mixed gas inside electrical equipment in the power grid.

[0016] Furthermore, when calculating the replenishment amount of SF6 gas and nitrogen, if the initial mixing ratio of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment is inconsistent with the target mixing ratio, the replenishment ratio of SF6 gas and nitrogen in the total replenishment amount of SF6 gas and nitrogen is calculated according to the total replenishment amount of SF6 gas and nitrogen and the initial mixing ratio and target mixing ratio of the mixed gas inside the electrical equipment, and the replenishment amounts of SF6 gas and nitrogen are obtained respectively.

[0017] Furthermore, “replenishing SF6 gas and nitrogen into the electrical equipment in sequence” also includes:

[0018] The current mixing ratio of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment is measured again.

[0019] Furthermore, if the proportion of SF6 gas in the current mixing ratio of the mixed gas consisting of SF6 gas and nitrogen inside the electrical equipment is lower than the proportion of SF6 gas in the target mixing ratio, continue to add SF6 gas to the electrical equipment so that the proportion of SF6 gas in the mixed gas exceeds the proportion of SF6 gas in the target mixing ratio.

[0020] Furthermore, a gas supply device is used to supply SF6 gas and nitrogen to the interior of the electrical equipment, and the gas tightness of the gas supply device is tested before the gas supply device is connected to the electrical equipment.

[0021] Furthermore, "detecting the air tightness of the air supply device" specifically includes: using a vacuum pump to evacuate the air supply device and measuring the pressure in the air supply device. When the pressure in the air supply device is below zero, turn off the vacuum pump and wait for 30 minutes. If the pressure in the air supply device does not return to zero, it indicates that the air tightness of the air supply device is good.

[0022] Beneficial effects of the present invention: The method for emergency gas replenishment of power grid equipment without power outage provided by the present application first measures the initial mixing ratio and initial pressure value of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment in the power grid, and then calculates the replenishment amounts of SF6 gas and nitrogen respectively in combination with the preset target mixing ratio and target pressure value of the mixed gas inside the electrical equipment, and reflects it through the real-time pressure value of the mixed gas inside the electrical equipment, replenishes SF6 gas and nitrogen into the electrical equipment in turn, replenishes SF6 gas until the real-time pressure value of the mixed gas reaches the pressure value corresponding to the corresponding SF6 gas replenishment amount, replenishes nitrogen until the real-time pressure value of the mixed gas reaches the target pressure value, and finally measures the current mixing ratio of the mixed gas inside the electrical equipment again to ensure that the proportion of SF6 gas in the mixed gas exceeds the proportion of SF6 gas in the target mixing ratio, thereby realizing automatic gas replenishment of the mixed gas of SF6 gas and nitrogen in the electrical equipment without power outage, and ensuring the safe operation of the equipment in the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart of the method.

[0024] Figure 2 It is a system schematic diagram of the gas replenishing device of the present invention.

[0025] Figure 3 It is a control schematic diagram of the air replenishing device of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0027] like Figure 1 As shown, the present invention provides a method for emergency gas supply without power outage of power grid equipment, comprising:

[0028] Step S1, sequentially measuring the initial mixing ratio and initial pressure value of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment in the power grid.

[0029] Step S2, when the initial pressure value of the mixed gas inside the electrical equipment is less than the preset pressure threshold, if the initial mixing ratio of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment is consistent with the target mixing ratio, the replenishment amounts of SF6 gas and nitrogen are calculated respectively according to the preset target mixing ratio and target pressure value of the mixed gas inside the electrical equipment, and SF6 gas and nitrogen are replenished into the electrical equipment in turn.

[0030] The calculation of the replenishment amount of SF6 gas and nitrogen specifically includes the following steps:

[0031] Step S21, calculating the total gas replenishment amount of SF6 gas and nitrogen according to the difference between the initial pressure value and the target pressure value of the mixed gas inside the electrical equipment;

[0032] Step S22, according to the target mixing ratio of the mixed gas inside the electrical equipment, calculate the gas replenishment ratio of SF6 gas and nitrogen in the total gas replenishment amount of SF6 gas and nitrogen, and obtain the gas replenishment amounts of SF6 gas and nitrogen respectively.

[0033] Specifically, the replenishment amount of SF6 gas and nitrogen is reflected by the real-time pressure value of the mixed gas inside the electrical equipment. The pressure difference between the initial pressure value and the target pressure value of the mixed gas inside the electrical equipment is divided into a first pressure interval and a second pressure interval according to the replenishment ratio of SF6 gas and nitrogen. The first pressure interval is from the first pressure value p1 to the second pressure value p2, and the second pressure interval is from the second pressure value p2 to the third pressure value p3. SF6 gas is replenished into the electrical equipment until the real-time pressure value of the mixed gas inside the electrical equipment reaches the second pressure value p2, and then nitrogen is replenished into the electrical equipment until the real-time pressure value of the mixed gas inside the electrical equipment reaches the third pressure value p3. The first pressure value p1 is the initial pressure value of the mixed gas inside the electrical equipment, and the third pressure value p3 is the target pressure value of the mixed gas inside the electrical equipment.

[0034] Step S3, if the initial mixing ratio of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment is inconsistent with the target mixing ratio, the gas replenishment ratio of SF6 gas and nitrogen in the total gas replenishment amount of SF6 gas and nitrogen is calculated according to the total gas replenishment amount of SF6 gas and nitrogen and the initial mixing ratio and target mixing ratio of the mixed gas inside the electrical equipment, the gas replenishment amount of SF6 gas and nitrogen is obtained respectively, and SF6 gas and nitrogen are replenished into the electrical equipment in turn.

[0035] Step S4, measure again the current mixing ratio of the mixed gas consisting of SF6 gas and nitrogen inside the electrical equipment. If the proportion of SF6 gas in the current mixing ratio of the mixed gas consisting of SF6 gas and nitrogen inside the electrical equipment is lower than the proportion of SF6 gas in the target mixing ratio, continue to add SF6 gas to the electrical equipment so that the proportion of SF6 gas in the mixed gas exceeds the proportion of SF6 gas in the target mixing ratio.

[0036] This application uses a gas replenishing device to replenish SF6 gas and nitrogen into the electrical equipment, and detects the air tightness of the gas replenishing device before connecting the gas replenishing device to the electrical equipment. Among them, "detecting the air tightness of the gas replenishing device" specifically includes: using a vacuum pump to evacuate the gas replenishing device and measure the pressure in the gas replenishing device. When the pressure in the gas replenishing device is below zero, turn off the vacuum pump and wait for 30 minutes. If the pressure in the gas replenishing device does not return to zero, it means that the gas replenishing device is in good air tightness.

[0037] Specifically, Figure 2 As shown, the gas replenishing device includes a multi-way connector 1, an SF6 gas cylinder 2 and a nitrogen gas cylinder 3. The multi-way connector 1 is connected to the electrical equipment 4 through a first pipeline 5. A pressure sensor P and a temperature sensor T are installed in the multi-way connector 1 to measure the pressure and temperature of the mixed gas in the electrical equipment 4. When the initial pressure value of the mixed gas in the electrical equipment 4 is lower than a preset pressure threshold, SF6 gas and nitrogen need to be replenished into the electrical equipment 4 according to a preset target mixing ratio.

[0038] The SF6 gas cylinder 2 is connected to the multi-way connector 1 through the second pipeline 6 to replenish SF6 gas into the electrical equipment 4. The nitrogen gas cylinder 3 is connected to the multi-way connector 1 through the third pipeline 7 to replenish nitrogen into the electrical equipment 4. A first solenoid valve DF1 is installed on the second pipeline 6, and a second solenoid valve DF2 is installed on the third pipeline 7 to control the replenishment amount of SF6 gas and nitrogen respectively.

[0039] like Figure 3As shown, the pressure sensor P, the temperature sensor T, the first solenoid valve DF1, and the second solenoid valve DF2 are all connected to the single-chip microcomputer for communication. The single-chip microcomputer is connected to a keyboard, and the keyboard is used for the staff to input the pressure threshold, the target pressure value, and the target mixing ratio to the single-chip microcomputer in advance. The pressure sensor P and the temperature sensor T measure the initial pressure value of the mixed gas in the electrical equipment 4 and upload it to the single-chip microcomputer for comparison with the pressure threshold. If the initial pressure value of the mixed gas is less than the pressure threshold, SF6 gas and nitrogen need to be added to the electrical equipment 4 to make the pressure of the mixed gas reach the target pressure value. The single-chip microcomputer calculates the ratio of SF6 gas and nitrogen that needs to be added to the electrical equipment 4 according to the target mixing ratio, and calculates the ratio between the initial pressure value of the mixed gas in the electrical equipment and the target pressure value. The pressure difference is divided into a first pressure interval and a second pressure interval according to the replenishment ratio of SF6 gas and nitrogen. The first pressure interval is from the first pressure value p1 to the second pressure value p2, and the second pressure interval is from the second pressure value p2 to the third pressure value p3. Among them, the first pressure value p1 is the initial pressure value of the mixed gas inside the electrical equipment, and the third pressure value p3 is the target pressure value of the mixed gas inside the electrical equipment. The single-chip microcomputer opens the first solenoid valve DF1 to replenish SF6 gas into the electrical equipment 4. When the pressure of the mixed gas reaches the second pressure value p2, the single-chip microcomputer closes the first solenoid valve DF1 and opens the second solenoid valve DF2 to replenish nitrogen into the electrical equipment 4. When the pressure of the mixed gas reaches the third pressure value p3, the single-chip microcomputer closes the second solenoid valve DF2.

[0040] The first pipeline 5 is provided with an electrically controlled three-way valve STF, which is connected to a mixing ratio tester 9 through a fourth pipeline 8 to measure the mixing ratio of the mixed gas in the electrical equipment 4. The electrically controlled three-way valve STF and the mixing ratio tester 9 are both connected to a single-chip microcomputer for communication. When the single-chip microcomputer controls the electrically controlled three-way valve STF to connect the mixing ratio tester 9 and the electrical equipment 4, the initial mixing ratio of the mixed gas in the electrical equipment 4 is measured by the mixing ratio tester 9. The single-chip microcomputer calculates the ratio of SF6 gas and nitrogen that needs to be added to the electrical equipment 4 based on the initial mixing ratio and the target mixing ratio of the mixed gas. The mixing ratio tester 9 uses the LX-3100M portable SF6 mixed gas (mixed gas ratio) detector, which can realize the quantitative analysis of the mixing ratio of the two mixed insulating gases SF6 / N2 and SF6 / CF4 without changing the analysis conditions, and monitor the oxygen concentration at the same time.

[0041] A first hand valve F1 is installed in series on the second pipeline 6 on one side of the first solenoid valve DF1, a second hand valve F2 is installed in series on the third pipeline 7 on one side of the second solenoid valve DF2, and a third hand valve F3 is installed in series on the first pipeline 5 between the electric three-way valve STF and the multi-way connector 1. The hand valves are all installed at the inlet of the solenoid valve. When the hand valve is in the open state, the solenoid valve will be activated, and the gas can flow through the pipeline through the solenoid valve. When the hand valve is closed, the solenoid valve loses the activation signal, thereby cutting off the pipeline flow. Through the series connection of the hand valve and the solenoid valve, the opening and closing of the valve can be controlled by manual operation, and the opening and closing of the solenoid valve can also be controlled by the single-chip microcomputer, realizing the function of combining manual operation and automatic control, which can not only meet the manual control needs of the operator, but also reduce the burden of the operator, improve the accuracy and stability of the automatic control, and when the solenoid valve fails, the power fails or other problems occur in the single-chip microcomputer, the hand valve can be manually operated to cut off the pipeline flow by physical means, thereby ensuring safety.

[0042] The first self-sealing valve ZFF1 is installed in series on the second pipeline 6 between the first solenoid valve DF1 / first hand valve F1 and the SF6 gas cylinder 2, the second self-sealing valve ZFF2 is installed in series on the third pipeline 7 between the second solenoid valve DF2 / second hand valve F2 and the nitrogen gas cylinder 3, the third self-sealing valve ZFF3 is installed in series on the first pipeline 5 between the third hand valve F3 and the electric-controlled three-way valve STF, and the fourth self-sealing valve ZFF4 is installed at the connection between the first pipeline 5 and the electrical equipment 4. The self-sealing valve has a self-sealing function, and when the equipment or connector is removed from the self-sealing valve, it can be automatically sealed to ensure that the SF6 gas will not leak.

[0043] The multi-way connector 1 is connected to a micro vacuum pump 11 through a fifth pipe 10. The micro vacuum pump 11 is used to evacuate the multi-way connector 1 and the first pipe 5, the second pipe 6, the third pipe 7, and the fifth pipe 10 to check the air tightness of the device. A fourth hand valve F4 is installed on the fifth pipe 10. When the micro vacuum pump 11 is started, the fourth hand valve F4 is opened to evacuate each gas path. When the pressure sensor P data is below zero, the micro vacuum pump 11 and the fourth hand valve F4 are closed. After waiting for a predetermined time, if the pressure sensor P data does not return to zero, it indicates that the air tightness of the device is good.

[0044] The first pressure reducing valve JYF1 is installed at the connection between the second pipeline 6 and the SF6 gas cylinder 2, and the second pressure reducing valve JYF2 is installed at the connection between the third pipeline 7 and the nitrogen gas cylinder 3. By setting the pressure reducing valve, the pressure at the outlet of the SF6 gas cylinder 2 and the nitrogen gas cylinder 3 is reduced to the preset pressure and output to the second pipeline 6 and the third pipeline 7, so that the pressure in the second pipeline 6 and the third pipeline 7 is kept stable.

[0045] The specific use process of the present invention is as follows:

[0046] The first step is to check the air tightness of the device;

[0047] Close the first solenoid valve DF1, the first hand valve F1, the second solenoid valve DF2, the second hand valve F2 and the third hand valve F3, open the fourth hand valve F4 and start the micro vacuum pump 11, evacuate the multi-way connector 1 and the first pipe 5, the second pipe 6, the third pipe 7 and the fifth pipe 10, when the pressure sensor P data is below zero, close the micro vacuum pump 11 and the fourth hand valve F4, wait for 30 minutes, if the pressure sensor P data does not return to zero, it means that the device is airtight.

[0048] The second step is to measure the initial mixing ratio of the mixed gas in the electrical device 4;

[0049] The single chip microcomputer controls the electrically controlled three-way valve STF to connect the mixing ratio tester 9 and the electrical equipment 4. The mixing ratio tester 9 measures that the initial mixing ratio of the mixed gas in the electrical equipment 4 is 60% SF6 gas and 40% nitrogen.

[0050] The third step is to measure the initial pressure value of the mixed gas in the electrical device 4;

[0051] The single chip microcomputer controls the electrically controlled three-way valve STF to connect the multi-way connector 1 with the electrical device 4, opens the third manual valve F3, and measures the initial pressure value of the mixed gas in the electrical device 4 to be 5 through the pressure sensor P and the temperature sensor T.

[0052] Step 4: Calculate the second pressure value p2 that needs to be reached for replenishing SF6 gas;

[0053] The single chip microcomputer compares the initial pressure value 5 of the mixed gas with the pressure threshold value 10, and obtains that SF6 gas and nitrogen need to be supplemented into the electrical equipment 4 to make the pressure of the mixed gas reach the target pressure value 15, and then obtains that the amount of mixed gas supplemented is twice the current amount of mixed gas. The single chip microcomputer then calculates that the ratio of SF6 gas and nitrogen that needs to be supplemented into the electrical equipment 4 is 9 / 1 based on the initial mixing ratio of the mixed gas (60% SF6 gas and 40% nitrogen) and the target mixing ratio (80% SF6 gas and 20% nitrogen), and then calculates the second pressure value p2 to be 14.

[0054] Step 5, replenishing SF6 gas and nitrogen into the electrical equipment 4 respectively;

[0055] Open the first manual valve F1 and the second manual valve F2, the single chip microcomputer controls the first solenoid valve DF1 to open, so as to add SF6 gas into the electrical equipment 4; when the pressure sensor P and the temperature sensor T measure the current pressure value of the mixed gas in the electrical equipment 4 to reach 14, the single chip microcomputer controls the first solenoid valve DF1 to close, and controls the second solenoid valve DF2 to open, so as to add nitrogen into the electrical equipment 4; when the pressure sensor P and the temperature sensor T measure the current pressure value of the mixed gas in the electrical equipment 4 to reach 15, the single chip microcomputer controls the second solenoid valve DF2 to close.

[0056] Step 6, measuring the current mixing ratio of the mixed gas in the electrical device 4 again;

[0057] After the SF6 gas and nitrogen are replenished into the electrical equipment 4 respectively, wait for 30 minutes, close the third manual valve F3, and the single chip microcomputer controls the electronically controlled three-way valve STF to connect the mixing ratio tester 9 with the electrical equipment 4. The current mixing ratio of the mixed gas in the electrical equipment 4 is measured again by the mixing ratio tester 9. If the proportion of SF6 gas in the current mixing ratio of the mixed gas is lower than the proportion of SF6 gas in the target mixing ratio, the single chip microcomputer controls the electronically controlled three-way valve STF to connect the multi-way connector 1 with the electrical equipment 4, open the third manual valve F3, and the single chip microcomputer controls the first solenoid valve DF1 to open, and continue to replenish the electrical equipment 4. SF6 gas is supplemented in the equipment 4 so that the proportion of SF6 gas in the mixed gas exceeds the proportion of SF6 gas in the target mixing ratio. When the current mixing ratio of the mixed gas reaches the preset target mixing ratio, the connection between the electrically controlled three-way valve STF and the electrical equipment 4 is disconnected from the fourth self-sealing valve ZFF4, the connection between the multi-way connector 1 and the electrically controlled three-way valve STF is disconnected from the third self-sealing valve ZFF3, the connection between the nitrogen cylinder 3 and the multi-way connector 1 is disconnected from the second self-sealing valve ZFF2, the connection between the SF6 cylinder 2 and the multi-way connector 1 is disconnected from the first self-sealing valve ZFF1, and the gas replenishing device is retracted.

[0058] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for emergency gas replenishment without power outage of power grid equipment, characterized in that: The following steps are involved: Measure the initial pressure value of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment in the power grid; When the initial pressure value of the mixed gas inside the electrical equipment is less than the preset pressure threshold, the replenishment amounts of SF6 gas and nitrogen are calculated respectively according to the preset target mixing ratio and target pressure value of the mixed gas inside the electrical equipment, and SF6 gas and nitrogen are replenished into the electrical equipment in turn.

2. The gas replenishing method according to claim 1, characterized in that: The calculation of the amount of SF6 gas and nitrogen to be added includes the following steps: Calculate the total gas replenishment volume of SF6 gas and nitrogen based on the difference between the initial pressure value and the target pressure value of the mixed gas inside the electrical equipment; According to the target mixing ratio of the mixed gas inside the electrical equipment, the gas replenishment ratio of SF6 gas and nitrogen in the total gas replenishment amount of SF6 gas and nitrogen is calculated to obtain the gas replenishment amounts of SF6 gas and nitrogen respectively.

3. The gas replenishing method according to claim 2, characterized in that: The replenishment amount of SF6 gas and nitrogen is reflected by the real-time pressure value of the mixed gas inside the electrical equipment. The pressure difference between the initial pressure value and the target pressure value of the mixed gas inside the electrical equipment is divided into a first pressure interval and a second pressure interval according to the replenishment ratio of SF6 gas and nitrogen. The first pressure interval is from the first pressure value p1 to the second pressure value p2, and the second pressure interval is from the second pressure value p2 to the third pressure value p3. SF6 gas is replenished into the electrical equipment until the real-time pressure value of the mixed gas inside the electrical equipment reaches the second pressure value p2, and then nitrogen is replenished into the electrical equipment until the real-time pressure value of the mixed gas inside the electrical equipment reaches the third pressure value p3. The first pressure value p1 is the initial pressure value of the mixed gas inside the electrical equipment, and the third pressure value p3 is the target pressure value of the mixed gas inside the electrical equipment.

4. The gas replenishing method according to claim 2, characterized in that: "Measurement of the pressure of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment in the power grid" also included: Measure the initial mixing ratio of SF6 gas and nitrogen mixed gas inside electrical equipment in the power grid.

5. The gas replenishing method according to claim 4, characterized in that: When calculating the replenishment amount of SF6 gas and nitrogen, if the initial mixing ratio of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment is inconsistent with the target mixing ratio, the replenishment ratio of SF6 gas and nitrogen in the total replenishment amount of SF6 gas and nitrogen is calculated according to the total replenishment amount of SF6 gas and nitrogen and the initial mixing ratio and target mixing ratio of the mixed gas inside the electrical equipment, and the replenishment amount of SF6 gas and nitrogen is obtained respectively.

6. The gas replenishing method according to claim 5, characterized in that: "Supplying SF6 gas and nitrogen into electrical equipment in sequence" also includes: The current mixing ratio of the mixed gas composed of SF6 gas and nitrogen inside the electrical equipment is measured again.

7. The gas replenishing method according to claim 6, characterized in that: If the proportion of SF6 gas in the current mixture ratio of SF6 gas and nitrogen inside the electrical equipment is lower than the proportion of SF6 gas in the target mixture ratio, continue to add SF6 gas to the electrical equipment so that the proportion of SF6 gas in the mixture exceeds the proportion of SF6 gas in the target mixture ratio.

8. The gas replenishing method according to claim 1, characterized in that: Use a gas supply device to supply SF6 gas and nitrogen to the interior of the electrical equipment. Before connecting the gas supply device to the electrical equipment, check the gas tightness of the gas supply device.

9. The gas replenishing method according to claim 8, characterized in that: "Detecting the air tightness of the air supply device" specifically includes: using a vacuum pump to evacuate the air supply device and measure the pressure in the air supply device. When the pressure in the air supply device is below zero, turn off the vacuum pump and wait for 30 minutes. If the pressure in the air supply device does not return to zero, it means that the air tightness of the air supply device is good.

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