Digital density relay with leakage measurement function

Abstract

The utility model discloses a digital density relay with a leakage measuring function, which comprises a first air cavity, a second air cavity and an air chamber connecting port, the air chamber connecting port is respectively connected with the first air cavity and the second air cavity through an air cavity pipeline, and electromagnetic valves are arranged on the air cavity pipeline and close to the air chamber connecting port and the first air cavity; the first air cavity and the second air cavity are each provided with a pressure sensor, a temperature sensor and a semiconductor temperature control module, and a piston adjusting assembly used for adjusting the volume of the air cavity is arranged in the first air cavity. The temperature of the two air cavities can be independently controlled, the two air cavities can also be communicated, the air pressure can be doubled in a one-temperature-rise and one-temperature-fall mode, the pressure sensor detection result in leakage measurement is subjected to temperature rise, pressure value increase and two-time amplification, the influence of the pressure sensor error on the measurement result is reduced, and the measurement accuracy is improved. The accuracy of a pressure measurement result is indirectly improved, so that the error of a density relay is reduced, and high-precision leakage measurement is realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of density relay, specifically relates to a digital density relay with leakage measurement function. BACKGROUND

[0002] Six fluorinated sulfur (SF6) gas possesses very strong greenhouse effect, its global warming potential (GWP) is 23900 times of CO2, and the atmospheric life is 3200 years, is one of 6 kinds of gases that the Kyoto protocol clearly requires to limit emission. Accurately grasping GIS equipment during operation SF6 gas leakage quantity / rate, carbon emission plan and judging leakage danger grade that the grid enterprise formulates possess important significance.

[0003] GAS insulated SWITCHGEAR (GIS) generally installs density relay to monitor SF6 gas density. Along with the development of micro sensing technology, the digital density relay of data can be gradually replaced by the remote transmission of traditional mechanical density relay, and its basic principle is that pressure sensor and temperature sensor monitor gas pressure and temperature respectively, and the pressure value at 20 DEG C under the isodensity is converted by Beattie-Bridgeman empirical equation. The annual leakage rate of GIS equipment is generally less than 0.5%, and the density drop is not obvious in the short term, and the measurement accuracy of digital density relay is most influenced by pressure sensor, but limited by the accuracy of pressure sensor, the error of the existing digital density relay is larger when measuring leakage, so the reliability of its leakage measurement result is not high.

[0004] In view of the above problems, it is urgent to study the leakage measurement technology of SF6 gas in GIS equipment, develop a digital density relay with leakage measurement function, improve the pressure measurement accuracy, combine the temperature sensor measurement result, calculate the leakage rate / quantity of SF6 gas in a given time interval, and provide data support for carbon emission accounting. UTILITY MODEL CONTENT

[0005] The technical problem to be solved by the utility model is how to solve the problem that the error of the current digital density relay is larger when measuring leakage.

[0006] To solve the above technical problems, the utility model provides the following technical scheme:

[0007] A digital density relay with leakage measurement function, comprising a first gas cavity, a second gas cavity and a gas chamber connecting port, the gas chamber connecting port is connected with the first gas cavity and the second gas cavity through a gas cavity pipeline, and an electromagnetic valve is arranged on the gas cavity pipeline and close to the gas chamber connecting port and the first gas cavity.

[0008] The first gas cavity and the second gas cavity are provided with pressure sensors, temperature sensors and semiconductor temperature control modules, and the inside of the first gas cavity is provided with a piston adjusting assembly for adjusting the volume of the gas cavity.

[0009] The first gas cavity and the second gas cavity can be independently controlled, and the two gas cavities can be communicated, and an electromagnetic valve is arranged on the communication pipeline, so that the two gas cavities are independently controlled in temperature, the cavity space can be adjusted through the piston adjusting assembly, the pressure of the gas is doubled in the mode of one heating and one cooling, the pressure value is increased, the pressure sensor detection results in the two amplification leakage measurement are amplified, the influence of the pressure sensor error on the measurement results is reduced, the accuracy of the pressure measurement results is indirectly improved, and the density relay error is reduced, so that high-precision leakage measurement is realized.

[0010] As a further scheme of the utility model: the piston adjusting assembly includes a piston and a baffle arranged in the first gas cavity, the piston is located on the side of the baffle facing the second gas cavity, and an electromagnetic baffle is arranged on the upper part of the inside of the first gas cavity for fixing the piston.

[0011] As a further scheme of the utility model: the electromagnetic baffle includes an electromagnet, a traction spring, an iron rod and an electromagnetic baffle outer wall, the electromagnetic baffle outer wall is mounted on the upper part of the first gas cavity and communicates with the same, the electromagnet is connected to the top of the electromagnetic baffle outer wall, and the bottom of the electromagnet is connected with the iron rod through the traction spring.

[0012] As a further scheme of the utility model: when the electromagnet is powered off, the iron rod pulls out the traction spring to resist the piston.

[0013] As a further scheme of the utility model: the first gas cavity is divided into chamber one and chamber two by the baffle, the piston is located in chamber two, and the outer wall of the first gas cavity is wrapped with a first semiconductor temperature control module for adjusting the temperature of chamber one.

[0014] As a further scheme of the utility model: the gas cavity pipeline includes a main pipeline, a branch pipeline one and a branch pipeline two, one end of the main pipeline is connected with the gas chamber connecting port, the other end is connected with the branch pipeline two through a three-way pipe, the two branch pipelines are respectively connected to chamber two in the second gas cavity and the first gas cavity, and the main pipeline is further communicated with the branch pipeline one and connected to chamber one in the first gas cavity through the branch pipeline one.

[0015] As a further scheme of the utility model: a first pressure sensor and a first temperature sensor are arranged above chamber one of the first gas cavity.

[0016] As a further scheme of the utility model: a second pressure sensor and a second temperature sensor are arranged above the second gas cavity.

[0017] As a further scheme of the present application: the first air cavity is internally provided with a cylindrical structure.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The density relay measurement error is mainly provided by the pressure sensor, and the pressure sensor error is a full-scale fixed value. When the actual pressure is lower, the error has a greater impact on the measurement result, i.e. the relative error is larger. Conversely, when the actual pressure is larger, the error has a smaller impact on the measurement result, i.e. the relative error is smaller. Since the SF6 gas GIS device has a small leakage rate, the density relay error cannot be ignored relative to the SF6 gas leakage amount in a short time. According to the ideal gas state equation, the gas pressure is positively correlated with the density and temperature. Therefore, the present application increases the gas pressure by doubling the density and increasing the temperature to 70℃, amplifies the pressure sensor detection result in the leakage measurement twice, reduces the impact of the pressure sensor error (fixed value) on the measurement result, indirectly improves the accuracy of the pressure measurement result, and further reduces the density relay error, so as to realize high-precision leakage measurement. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a structural schematic diagram of a digital density relay according to an embodiment of the present application;

[0021] Figure 2 FIG. 2 is a structural schematic diagram of an electromagnetic baffle according to an embodiment of the present application;

[0022] MARKS DESCRIPTION:

[0023] 1, gas chamber connecting port; 2, first electromagnetic valve; 3, first pressure sensor; 4, first temperature sensor; 5, first air cavity; 6, first semiconductor temperature control module; 7, electromagnetic baffle; 71, electromagnet; 72, traction spring; 73, iron bar; 74, electromagnetic baffle outer wall; 8, baffle; 9, piston; 10, second electromagnetic valve; 11, third electromagnetic valve; 12, second pressure sensor; 13, second semiconductor temperature control module; 14, second temperature sensor; 15, second air cavity. DETAILED DESCRIPTION

[0024] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] REFERENCEFigure 1 The utility model provides a digital density relay with leakage measuring function, including gas chamber connecting port 1, first gas cavity 5 and second gas cavity 15, wherein the one end of gas chamber connecting port 1 is connected to the gas chamber of GIS equipment, the other end of gas chamber connecting port 1 is connected to gas main pipeline, the other end of gas main pipeline is connected to three-way pipe, and the other two outlets of three-way pipe are connected to the rear end of first gas cavity 5 and second gas cavity 15 through branch pipeline two, and branch pipeline one is further communicated in the middle of main pipeline, and the other end of branch pipeline one is connected to the front end of first gas cavity 5.

[0026] Further, the end of gas main pipeline close to gas chamber connecting port 1 is provided with first electromagnetic valve 2, branch pipeline one is provided with second electromagnetic valve 10, and branch pipeline two connected to first gas cavity 5 is provided with third electromagnetic valve 11.

[0027] Referring to Figure 1 The inside of first gas cavity 5 is provided with cylindrical structure, and the top and bottom of first gas cavity 5 are provided with baffle 8, baffle 8 divides the inside cavity of first gas cavity 5 into chamber one and chamber two, the piston 9 is slidably connected in chamber two, and the electromagnetic baffle 7 for fixing piston 9 is arranged at the position close to baffle 8 on the inside top of chamber two.

[0028] It should be noted that branch pipeline one is connected to the inside chamber one of first gas cavity 5, and branch pipeline two is connected to the inside chamber two of first gas cavity 5; piston 9 is located in chamber two.

[0029] Referring to Figure 1 The first pressure sensor 3 and the first temperature sensor 4 are arranged on the outer wall of first gas cavity 5 and the upper part of chamber one, and the first semiconductor temperature control module 6 is wrapped on the outer wall of first gas cavity 5, the first semiconductor temperature control module 6 only wraps part of chamber one, and the position thereof does not exceed baffle 8, so as to control the temperature in chamber one and avoid controlling the temperature of the gas in chamber two on the right side of piston 9.

[0030] Further, referring to Figure 2 The electromagnetic baffle 7 includes electromagnet 71, traction spring 72, iron rod 73 and electromagnetic baffle outer wall 74, the electromagnetic baffle outer wall 74 is installed on the upper part of first gas cavity 5 and communicates with the same, the electromagnet 71 is connected to the top of electromagnetic baffle outer wall 74, and the bottom of electromagnet 71 is connected with iron rod 73 through traction spring 72; when the electromagnet 71 is powered off, the iron rod 73 pulls traction spring 72 to extend and can abut against piston 9 to limit the same.

[0031] Referring to Figure 1 The outside of second gas cavity 15 is wrapped with second semiconductor temperature control module 13, and the second gas cavity 15 is further provided with second pressure sensor 12 and second temperature sensor 14 for detecting the pressure and temperature in second gas cavity 15.

[0032] It should be noted that, in the case of non-leakage measurement, the piston 9 is close to the inner chamber of the first gas cavity 5 on the side close to the third pressure sensor 11, at this time the effective volume of the first gas cavity 5 is V; when the piston 9 is blocked by the baffle 8, the effective volume of the cavity on one side of the baffle 8 (i.e. chamber one) is 0.5V; the effective volume of the second gas cavity 14 is fixed at 1.5V.

[0033] Under normal circumstances, the first electromagnetic valve 2 and the second electromagnetic valve 10 are opened, and the first pressure sensor 3 and the first temperature sensor 4, the second pressure sensor 12 and the second temperature sensor 14 normally detect the temperature and pressure of the SF6 gas in the gas chamber, calculate the SF6 gas density according to the Betty Bridge Man empirical formula, and check and correct each other, thereby improving the reliability of the density monitoring result.

[0034] The specific operation principle of the present application is as follows:

[0035] Step one, close the first electromagnetic valve 2, the second electromagnetic valve 10 and the third electromagnetic valve 11, and start the first semiconductor refrigerator 6 and the second semiconductor refrigerator 13; wherein the first semiconductor refrigerator 6 is set to -43.8℃ for the refrigeration temperature in the first gas cavity 5, and the second semiconductor refrigerator 14 is heated by reverse power supply, and the temperature is set to 70℃;

[0036] When it is -43.8℃, the pressure in the first gas cavity 5 is low due to the cooling, and part of the SF6 gas in the first gas cavity 5 is liquefied, at this time the pressure in the first gas cavity 5 is constant at 0.3MPa; the pressure of the normal SF6 electrical equipment is higher than 0.45MPa (20℃, absolute pressure); the pressure in the second gas cavity 15 is high due to the heating;

[0037] Step two, keep the temperature control for 3h after the temperature is set, open the third electromagnetic valve 11, at this time the pressure in the first gas cavity 5 is constant at 0.3MPa, and the gas pressure in the second gas cavity 15 is high (according to the initial 20℃, 0.45MPa, the pressure at 70℃ is about 0.52MPa according to the ideal gas state equation), the high pressure gas will push the piston 9 to move to the baffle 8 through the branch pipe two;

[0038] It should be noted that,

[0039] When it is detected that the pressure in the second gas cavity 15 no longer decreases, it means that the piston has reached the baffle 8, at this time the pressure on the right side of the piston 9 is about 0.34MPa, then the third electromagnetic valve 11 and the second semiconductor refrigerator 13 are closed, the electromagnet 71 is de-energized and demagnetized, and the iron bar 73 partially extends out of the outer wall of the electromagnetic baffle to block the piston 9, at this time the gas in the first gas cavity 5 is completely moved to chamber one, the effective volume of the chamber is reduced to 0.5V, and the gas density is increased;

[0040] Step three, then the first semiconductor refrigerator 6 reverse power heating to 70 DEG C, after 3h by the first pressure sensor 3 and the first temperature sensor 4 detection current pressure and temperature, according to Beattie-Bridgeman empirical formula calculation SF6 gas density is p;

[0041] Step four, the p and the last time to carry out the leakage measurement obtained SF6 gas density p0 difference, recorded as delta p, that is, the two leakage measurement during the gas chamber SF6 gas leakage, the sum of the historical leakage measurement data, that is, the total leakage ms can be obtained;

[0042] 0.5 delta p x Vs = ms

[0043] Because the volume of chamber one is the original total chamber reduced by half, the chamber one density becomes 1 / 2 times the actual density, that is, 0.5 delta p; Vs is the effective volume of the connected GIS device gas chamber.

[0044] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A digital density relay with a leakage measuring function, characterized by comprising: It comprises a first air cavity (5), a second air cavity (15) and an air chamber connecting port (1), the air chamber connecting port (1) is connected with the first air cavity (5) and the second air cavity (15) through air cavity pipelines, and an electromagnetic valve is arranged on the air cavity pipeline and close to the air chamber connecting port (1) and the first air cavity (5). Pressure sensors, temperature sensors and semiconductor temperature control modules are arranged on the first air cavity (5) and the second air cavity (15), and a piston adjusting assembly for adjusting the volume of the air cavity is arranged in the first air cavity (5).

2. The digital density relay with a leakage measuring function according to claim 1, characterized in that: The piston adjusting assembly comprises a piston (9) and a baffle (8) arranged in the first air cavity (5), the piston (9) is located on the side of the baffle (8) facing the second air cavity (15), and an electromagnetic baffle (7) for fixing the piston (9) is arranged on the inner side of the upper portion of the first air cavity (5).

3. The digital density relay with a leakage measuring function according to claim 2, characterized in that: The electromagnetic baffle (7) comprises an electromagnet (71), a traction spring (72), an iron rod (73) and an electromagnetic baffle outer wall (74), the electromagnetic baffle outer wall (74) is mounted on the upper portion of the first air cavity (5) and communicates with the first air cavity (5), the electromagnet (71) is connected to the top of the electromagnetic baffle outer wall (74), and the bottom of the electromagnet (71) is connected with the iron rod (73) through the traction spring (72).

4. The digital density relay with a leakage measuring function according to claim 3, characterized in that: When the electromagnet (71) is powered off, the iron rod (73) pulls the traction spring (72) to extend and can resist the piston (9).

5. The digital density relay with a leakage measuring function according to claim 2, characterized in that: The first air cavity (5) is divided into chamber one and chamber two by the baffle (8), the piston (9) is located in the chamber two, and the outer wall of the first air cavity (5) is wrapped with a first semiconductor temperature control module (6) for adjusting the temperature of the chamber one.

6. The digital density relay with a leakage measuring function according to claim 5, characterized in that: The air cavity pipeline comprises a main pipeline and a branch pipeline one, one end of the main pipeline is connected with the air chamber connecting port (1), the other end is connected with a branch pipeline two through a three-way pipe, two branch pipelines are connected to the chamber two in the second air cavity (15) and the first air cavity (5) respectively, and the main pipeline is also connected with the branch pipeline one and connected to the chamber one in the first air cavity (5) through the branch pipeline one.

7. The digital density relay with a leakage measuring function according to claim 5, characterized in that: The first pressure sensor (3) and the first temperature sensor (4) are arranged above the chamber one of the first air cavity (5).

8. The digital density relay with a leakage measuring function according to claim 1, characterized in that: The second pressure sensor (12) and the second temperature sensor (14) are arranged above the second air cavity (15).

9. The digital density relay with a leakage measuring function according to claim 1, characterized in that: The first air cavity (5) is arranged in a cylindrical structure.

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