A method for testing the maximum reverse oil flow of a gas relay

Abstract

The present invention relates to the technical field of transformers, and in particular to a method for testing the maximum reverse oil flow of a gas relay, which includes: selecting the condition with the largest volume of single oil injection of the pressure relief valve at different oil temperatures and pressurization speeds, allowing the insulating oil in the conservator to flow through the transformer connecting pipe to replenish oil to the transformer body, conducting a force analysis, calculating the resultant force received by the replenishing insulating oil in the transformer connecting pipe, and then calculating the acceleration and maximum speed values during the oil replenishment process. Comparing the maximum speed value of the insulating oil during the oil replenishment process with the specified positive maximum setting oil flow rate, and taking the larger value as the oil flow rate value for the reverse oil flow test of the gas relay. The present invention fully considers the influencing factors of the reverse oil flow rate under actual conditions and combines the standards in the existing reverse oil flow test to test the gas relay, which helps to comprehensively evaluate the stability and reliability of the gas relay during actual operation.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a method for testing the maximum reverse oil flow of a gas relay. Background Art

[0002] A pressure relief valve is a safety valve used to protect transformer equipment. When the internal pressure of the transformer exceeds a preset threshold, the pressure relief valve will be activated and opened to release the oil in the main transformer body to relieve the pressure of the transformer and prevent the transformer from being damaged or endangered due to excessive pressure. At the same time, when the pressure relief valve operates and the oil in the main transformer body is released, the insulating oil in the conservator tank enters the main body to form a reverse oil flow.

[0003] A gas relay is a device that uses gas pressure to control electrical signals. It converts the gas source pressure signal into mechanical motion through pneumatic components, and then controls the on-off or other operations of the circuit. The lower floating ball of the gas relay is easily affected by the reverse oil flow and may malfunction. Therefore, in order to verify the reliability and stability of the gas relay for transformers in the actual working environment, a reverse oil flow test needs to be carried out before the gas relay for transformers is put into use to evaluate the performance of the gas relay when it is affected by the reverse oil flow in the hydraulic system, so as to ensure that it can work normally under specific working conditions and will not cause failures or damages due to the reverse oil flow.

[0004] According to JB / T 9647-2014 "Gas Relay for Transformers", the reverse oil flow test of the gas relay uses the maximum rated forward oil flow rate as the oil flow rate value for the reverse oil flow test to screen qualified gas relays that pass the reverse oil flow test. However, in actual use, due to factors such as the height of the conservator tank, the oil injection volume of the pressure relief valve, and the inclination angle of the connecting pipe of the gas relay, the reverse oil flow of the gas relay may exceed the oil flow rate value of the reverse oil flow test, and the problems that may occur in the gas relay under high-speed reverse oil flow, such as leakage, vibration, and wear, cannot be triggered, resulting in potential problems not being discovered and unqualified gas relays entering the power grid.

[0005] Therefore, the existing reverse oil flow test of the gas relay cannot simulate the reverse oil flow situation under actual working conditions and cannot accurately evaluate the performance of the gas relay in the actual working environment. Summary of the Invention

[0006] For this reason, the technical problem to be solved by the present invention is to overcome the problem that the reverse oil flow test of the gas relay in the prior art cannot accurately evaluate the performance of the gas relay in the actual working environment.

[0007] To solve the above technical problem, the present invention provides a method for testing the maximum reverse oil flow of a gas relay, including:

[0008] On the pressure relief valve displacement performance test platform, measure the volume of the single oil injection of the pressure relief valve for the transformer insulating oil at different oil temperatures and different pressurization speeds. Select the maximum volume of the single oil injection of the pressure relief valve and record the corresponding oil temperature.

[0009] After the pressure relief valve injects oil, the insulating oil in the conservator flows through the transformer connecting pipe to replenish oil to the transformer body, and calculate the distance of the replenishing insulating oil in the transformer connecting pipe.

[0010] Conduct a force analysis, calculate the static pressure generated when the insulating oil in the conservator takes the highest position, the self-weight of the replenishing insulating oil, and the frictional force of the replenishing insulating oil flowing in the transformer connecting pipe, and then calculate the resultant force received by the replenishing insulating oil in the transformer connecting pipe.

[0011] Calculate the acceleration of the oil replenishment process based on the resultant force received by the replenishing insulating oil in the transformer connecting pipe, and then calculate the maximum speed value of the insulating oil during the oil replenishment process.

[0012] Compare the maximum speed value of the insulating oil during the oil replenishment process with the maximum set positive oil flow rate. If the maximum speed value of the insulating oil during the oil replenishment process is greater than the maximum set positive oil flow rate, then use the maximum speed value of the insulating oil during the oil replenishment process as the oil flow rate value for the reverse oil flow test of the gas relay; otherwise, use the maximum set positive oil flow rate as the oil flow rate value for the reverse oil flow test of the gas relay.

[0013] Preferably, on the pressure relief valve displacement performance test platform, measure the volume of the single oil injection of the pressure relief valve for the transformer insulating oil at different oil temperatures and different pressurization speeds. Select the maximum volume of the single oil injection of the pressure relief valve and record the corresponding oil temperature, including:

[0014] The value range of the oil temperature is from the lowest operating temperature of the transformer to 115 °C, with an interval of 5 °C; the value range of the pressurization speed is from 20 kPa / s to 60 kPa / s, with an interval of 20 kPa / s; measure the volume of the single oil injection of the pressure relief valve when the transformer insulating oil is at different oil temperatures and different pressurization speeds.

[0015] Select the maximum volume V of the single oil injection of the pressure relief valve 1 , and record the corresponding oil temperature t.

[0016] Preferably, after the pressure relief valve injects oil, the insulating oil in the conservator flows through the transformer connecting pipe to replenish oil to the transformer body, and calculate the distance of the replenishing insulating oil in the transformer connecting pipe, including:

[0017] The transformer connecting pipe is a circular pipe with a diameter of 80 mm. If the volume V of the replenishing insulating oil 2 is equal to the maximum volume of the single oil injection of the pressure relief valve, then the distance of the replenishing insulating oil in the transformer connecting pipe is:

[0018]

[0019] Among them, L is the distance of the insulating oil for supplementary oil filling in the transformer connecting pipe, and S is the flow cross-sectional area of the supplementary oil filling oil path channel in the transformer connecting pipe.

[0020] Preferably, calculating the static pressure generated when the insulating oil in the conservator takes the highest level includes:

[0021] F 1 = ρghS

[0022] Among them, F 1 is the static pressure generated when the insulating oil in the conservator takes the highest level, ρ is the density of the insulating oil at the oil temperature corresponding to the maximum volume of oil sprayed by the pressure relief valve each time, g is the acceleration due to gravity, h is the vertical distance from the highest oil level in the conservator to the gas relay, and S is the flow cross-sectional area of the supplementary oil filling oil path channel in the transformer connecting pipe.

[0023] Preferably, calculating the self-gravity of the insulating oil for supplementary oil filling includes:

[0024] G = ρV 2 g

[0025] Among them, G is the self-gravity of the insulating oil for supplementary oil filling, ρ is the density of the insulating oil at the oil temperature corresponding to the maximum volume of oil sprayed by the pressure relief valve each time, g is the acceleration due to gravity, and V 2 is the volume of the insulating oil for supplementary oil filling.

[0026] Preferably, calculating the frictional force of the insulating oil for supplementary oil filling flowing in the transformer connecting pipe includes:

[0027] F f = μG·cosθ

[0028] Among them, F f is the frictional force of the insulating oil for supplementary oil filling flowing in the transformer connecting pipe, G is the self-gravity of the insulating oil for supplementary oil filling, μ is the friction coefficient of the insulating oil for supplementary oil filling in the transformer connecting pipe, and θ is the angle between the transformer connecting pipe and the horizontal direction.

[0029] Preferably, calculating the resultant force received by the insulating oil for supplementary oil filling in the transformer connecting pipe includes:

[0030] F = F 1 + G sinθ - F f

[0031] Among them, F is the resultant force received by the insulating oil for supplementary oil filling along the pipeline direction in the transformer connecting pipe, F 1 is the static pressure generated when the insulating oil in the conservator takes the highest level, G is the self-gravity of the insulating oil for supplementary oil filling, θ is the angle between the transformer connecting pipe and the horizontal direction, and F fThe frictional force of the insulating oil for oil replenishment flowing in the transformer connecting pipe.

[0032] Preferably, the acceleration of the oil replenishment process is calculated based on the resultant force received by the insulating oil for oil replenishment in the transformer connecting pipe, including:

[0033]

[0034] m = ρV 2

[0035] where a is the acceleration of the oil replenishment process, F is the resultant force received by the insulating oil for oil replenishment in the transformer connecting pipe along the pipeline direction, m is the mass of the insulating oil for oil replenishment, ρ is the density of the insulating oil at the oil temperature corresponding to the maximum volume of single oil injection of the pressure relief valve, g is the acceleration due to gravity, and V 2 is the volume of the insulating oil for oil replenishment.

[0036] Preferably, calculating the maximum velocity value of the insulating oil in the oil replenishment process includes:

[0037]

[0038] where v is the maximum velocity value of the insulating oil in the oil replenishment process, a is the acceleration of the oil replenishment process, and L is the distance of the insulating oil for oil replenishment in the transformer connecting pipe.

[0039] Preferably, the forward maximum setting oil flow rate is the oil flow rate value of the reverse oil flow test specified in JB / T 9647-2014.

[0040] The above technical solutions of the present invention have the following beneficial effects compared with the prior art:

[0041] A method for the maximum reverse oil flow test of a gas relay according to the present invention simulates the single - time oil injection of a pressure relief valve under different oil temperatures and different pressurization speeds in an actual situation, and selects the situation with the largest single - time oil injection volume of the pressure relief valve. Then, the insulating oil in the conservator is made to replenish the transformer body through the transformer connecting pipe, and the force analysis of the replenishment process is carried out. The resultant force received by the replenishing insulating oil in the transformer connecting pipe is calculated, and then the acceleration and the maximum speed value during the replenishment process are calculated. The maximum speed value of the insulating oil during the replenishment process is compared with the oil flow velocity value specified in JB / T 9647 - 2014 "Gas Relays for Transformers", that is, the maximum positive setting oil flow velocity, and the larger value is used as the oil flow velocity value for the reverse oil flow test of the gas relay. The present invention fully considers the influence of factors such as the height of the conservator, the oil injection volume of the pressure relief valve, and the inclination angle of the gas relay connecting pipe on the reverse oil flow velocity in an actual situation, and combines the existing standards in the reverse oil flow test to test the gas relay, which helps to comprehensively evaluate the stability and reliability of the gas relay in actual operation, improve the qualification rate of screening gas relays in the reverse oil flow test, and improve the quality of gas relays in the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in conjunction with the drawings, where

[0043] Figure 1 is a flow chart of a method for the maximum reverse oil flow test of a gas relay according to the present invention;

[0044] Figure 2 is a force analysis diagram of the insulating oil during the oil replenishment process. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following further illustrates the present invention in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the examples given are not intended to limit the present invention.

[0046] Referring to Figure 1 as shown, the present invention provides a method for the maximum reverse oil flow test of a gas relay, which specifically includes the following steps:

[0047] S1. On the pressure relief valve displacement performance test platform, measure the volume of single - time oil injection of the pressure relief valve for the transformer insulating oil under different oil temperatures and different pressurization speeds, where the value range of the oil temperature is from the lowest operating temperature of the transformer to 115 °C, with an interval of 5 °C; the value range of the pressurization speed is from 20 kPa / s to 60 kPa / s, with an interval of 20 kPa / s.

[0048] Select the maximum volume V of single - time oil injection of the pressure relief valve 1, and record the corresponding oil temperature t.

[0049] S2. After the pressure relief valve sprays oil, the insulating oil in the conservator flows through the transformer connecting pipe to replenish oil to the transformer body. The transformer connecting pipe is a circular pipe with a diameter of 80 mm, and the volume V of the insulating oil for replenishment 2 is equal to the maximum volume of oil sprayed by the pressure relief valve once, then the distance traveled by the insulating oil for replenishment in the transformer connecting pipe is:

[0050]

[0051] where L is the distance traveled by the insulating oil for replenishment in the transformer connecting pipe, and S is the flow cross-sectional area of the oil replenishment passage in the transformer connecting pipe.

[0052] S3. Referring to item 2 above, perform a force analysis. During the oil replenishment process, the insulating oil is subjected to the action of three forces, namely, the static pressure generated by the height of the insulating oil in the conservator, the self-gravity of the insulating oil for replenishment, and the frictional force of the insulating oil for replenishment flowing in the transformer connecting pipe.

[0053] Analyze the static pressure. In order to obtain the maximum reverse oil flow rate inside the gas relay, the oil inside the conservator is taken at the highest oil level for analysis and calculation. The formula is:

[0054] F 1 = ρghS

[0055] where F 1 is the static pressure generated when the insulating oil in the conservator is at the highest level, ρ is the density of the insulating oil at the oil temperature t, g is the acceleration due to gravity, h is the vertical distance from the highest oil level in the conservator to the gas relay, and S is the flow cross-sectional area of the oil replenishment passage in the transformer connecting pipe.

[0056] Analyze the self-gravity of the insulating oil. The formula is:

[0057] G = ρV 2 g

[0058] where G is the self-gravity of the insulating oil for replenishment, and V 2 is the volume of the insulating oil for replenishment.

[0059] Analyze the frictional force of the insulating oil flowing in the transformer connecting pipe. The formula is

[0060] F f = μG·cosθ

[0061] where F f is the frictional force of the insulating oil for replenishment flowing in the transformer connecting pipe, μ is the friction coefficient of the insulating oil for replenishment in the transformer connecting pipe, and θ is the angle between the transformer connecting pipe and the horizontal direction.

[0062] Conduct a comprehensive stress analysis on the insulating oil in the transformer connecting pipe during the oil replenishment process. The formula is as follows:

[0063] F = F 1 + G sinθ - F f

[0064] Among them, F is the resultant force received by the insulating oil for oil replenishment along the pipeline direction in the transformer connecting pipe.

[0065] S4. Calculate the acceleration during the oil replenishment process based on the resultant force received by the insulating oil for oil replenishment in the transformer connecting pipe. The formula is as follows:

[0066]

[0067] m = ρV 2

[0068] Among them, a is the acceleration during the oil replenishment process, F is the resultant force received by the insulating oil for oil replenishment along the pipeline direction in the transformer connecting pipe, m is the mass of the insulating oil for oil replenishment, ρ is the density of the insulating oil at the oil temperature of t, g is the acceleration due to gravity, and V 2 is the volume of the insulating oil for oil replenishment.

[0069] The oil replenishment process can be regarded as a uniformly accelerated linear motion with an initial velocity of 0. Then, the maximum velocity value of the insulating oil during the oil replenishment process is:

[0070]

[0071] Among them, v is the maximum velocity value during the oil replenishment process, and L is the distance traveled by the insulating oil for oil replenishment in the transformer connecting pipe.

[0072] S5. Compare the maximum velocity value of the insulating oil during the oil replenishment process with the maximum set positive oil flow velocity. If the maximum velocity value of the insulating oil during the oil replenishment process is greater than the maximum set positive oil flow velocity, then use the maximum velocity value of the insulating oil during the oil replenishment process as the oil flow velocity value for the reverse oil flow test of the gas relay; otherwise, use the maximum set positive oil flow velocity as the oil flow velocity value for the reverse oil flow test of the gas relay.

[0073] To sum up, the present invention fully considers the influence of the conservator height, the oil spraying volume of the pressure relief valve, the inclination angle of the gas relay connecting pipe, etc. on the reverse oil flow velocity under actual conditions, and conducts tests on the gas relay in combination with the standards in the existing reverse oil flow test, which helps to comprehensively evaluate the stability and reliability of the gas relay during actual operation, improve the qualification rate of screening gas relays in the reverse oil flow test, and improve the quality of gas relays in the power grid.

[0074] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A gas relay maximum reverse oil flow test method, characterized in that: include: On the pressure relief valve displacement performance test platform, measure the volume of transformer insulating oil injected by the pressure relief valve at different oil temperatures and different boost speeds, select the maximum volume of the pressure relief valve injected by the pressure relief valve and record the corresponding oil temperature; After the pressure relief valve sprays oil, the insulating oil in the oil conservator flows through the transformer coupling pipe to replenish the transformer body. The distance of the replenished insulating oil in the transformer coupling pipe is calculated; Conduct force analysis to calculate the static pressure generated when the insulating oil in the oil conservator is at the highest position and the gravity of the insulating oil itself when filling the oil; Then calculate the friction force of the insulating oil flowing in the transformer coupling pipe, the formula is: ； in, The friction of the insulating oil flowing in the transformer coupling pipe is The gravity of the insulating oil used for filling is The friction coefficient of the insulating oil in the transformer coupling is is the angle between the transformer coupling and the horizontal direction; The formula for calculating the resultant force on the insulating oil in the transformer coupling is: ； in, The resultant force on the insulating oil in the transformer coupling along the pipeline direction is: It is the static pressure generated when the insulating oil in the oil conservator is at the highest position; The acceleration of the oil filling process is calculated according to the resultant force on the insulating oil in the transformer coupling pipe, and then the maximum velocity value of the insulating oil in the oil filling process is calculated; Compare the maximum speed value of the insulating oil in the oil replenishing process and the maximum set oil flow rate in the forward direction. If the maximum speed value of the insulating oil in the oil replenishing process is greater than the maximum set oil flow rate in the forward direction, the maximum speed value of the insulating oil in the oil replenishing process will be used as the oil flow rate value of the reverse oil flow test of the gas relay; otherwise, the maximum set oil flow rate in the forward direction will be used as the oil flow rate value of the reverse oil flow test of the gas relay.

2. A gas relay maximum reverse oil flow test method according to claim 1, characterized in that: On the pressure relief valve displacement performance test platform, measure the volume of transformer insulating oil injected by the pressure relief valve at different oil temperatures and different boost speeds, select the maximum volume of the pressure relief valve injected by the pressure relief valve and record the corresponding oil temperature, including: The oil temperature range is from the lowest operating temperature of the transformer to 115°C, with an interval of 5°C; the boost speed range is from 20kPa / s to 60kPa / s, with an interval of 20kPa / s; the volume of a single oil injection of the pressure relief valve is measured at different oil temperatures and boost speeds for the transformer insulating oil; Select the maximum volume of a single injection of the pressure relief valve , and record the corresponding oil temperature t.

3. A gas relay maximum reverse oil flow test method according to claim 1, characterized in that: After the pressure relief valve sprays oil, the insulating oil in the oil conservator flows through the transformer coupling pipe to replenish the transformer body. The distance of the replenishing insulating oil in the transformer coupling pipe is calculated, including: The transformer coupling pipe is a circular pipe with a diameter of 80 mm. The insulating oil volume of the oil replenishment is If the maximum volume of oil injected by the pressure relief valve in a single injection is equal to that of the oil injected in the transformer, the distance of the insulating oil in the transformer coupling pipe is: ； in, The distance of the insulating oil in the transformer coupling pipe for oil replenishment. It is the flow cross-sectional area of ​​the oil supply channel in the transformer coupling pipe.

4. A gas relay maximum reverse oil flow test method according to claim 1, characterized in that: Calculate the static pressure generated when the insulating oil in the oil conservator is at the highest level, including: ； in, It is the static pressure generated when the insulating oil in the oil conservator is at the highest position. The density of the insulating oil at the oil temperature corresponding to the maximum volume of a single oil injection of the pressure relief valve, is the acceleration due to gravity, It is the vertical distance from the highest oil level in the oil conservator to the gas relay. It is the flow cross-sectional area of ​​the oil supply channel in the transformer coupling pipe.

5. A gas relay maximum reverse oil flow test method according to claim 1, characterized in that: Calculate the weight of the insulating oil itself for oil replenishment, including: ； in, The gravity of the insulating oil used for filling is The density of the insulating oil at the oil temperature corresponding to the maximum volume of a single oil injection of the pressure relief valve, is the acceleration due to gravity, is the volume of insulating oil for replenishment.

6. A gas relay maximum reverse oil flow test method according to claim 1, characterized in that: The acceleration of the oil filling process is calculated based on the combined force on the insulating oil in the transformer coupling, including: ； ； in, is the acceleration of the oil filling process, The resultant force on the insulating oil in the transformer coupling along the pipeline direction is: The quality of the insulating oil for filling oil, The density of the insulating oil at the oil temperature corresponding to the maximum volume of a single oil injection of the pressure relief valve, is the acceleration due to gravity, is the volume of insulating oil for replenishment.

7. A gas relay maximum reverse oil flow test method according to claim 6, characterized in that: Calculate the maximum speed value of insulating oil during the oil filling process, including: ； in, is the maximum speed value of the insulating oil during the oil filling process, is the acceleration of the oil filling process, The distance traveled by the insulating oil for oil replenishment in the transformer coupling pipe.

8. A gas relay maximum reverse oil flow test method according to claim 1, characterized in that: The forward maximum set oil flow rate is the oil flow rate value of the reverse oil flow test specified in JB / T 9647-2014 "Gas Relay for Transformer".

Images