A micro-water density online monitoring system

Abstract

The present invention discloses an online monitoring system for micro-water density, and the present invention relates to the technical field of circuit breaker monitoring. By setting an analysis and judgment unit and a simulation monitoring unit, the preset SF6 gas can be used as verification data before the data acquisition unit works. Since the preset micro-water density, gas density, gas pressure and gas temperature of the SF6 gas are all preset values, the data detected by the comparison sensor is compared with the preset values ​​of the SF6 gas, and the difference between the detection value and the preset value is analyzed and judged, so that the working state of each sensor can be analyzed, and whether there is a detection fault in the sensor can be found in time, and the fault can be found and eliminated before the micro-water density online monitoring system works, so as to avoid the situation that the micro-water density online monitoring system outputs wrong micro-water density detection data due to its own fault when working, and improve the accuracy of the detection result of the micro-water density online monitoring system.

Description

Technical Field

[0001] The invention relates to the technical field of circuit breaker monitoring, and in particular to an online monitoring system for micro-water density. Background Art

[0002] A circuit breaker is an electrical switching device that has the ability to carry and disconnect current under normal conditions, and can carry and disconnect current within a specified time under abnormal conditions. It can be used to distribute electrical energy and protect power lines and motors from severe overloads, short circuits, and undervoltage faults. SF6 circuit breakers are a special type of circuit breaker that uses SF6 gas as an insulating medium.

[0003] Among them, the micro-water density content in SF6 gas refers to the density of the space occupied by tiny water molecules in the medium. In many cases, micro-water density is usually used to describe the content or concentration of water molecules in a certain medium. Micro-water monitoring refers to the content and concentration of tiny water molecules in the monitoring system or equipment. In many industrial and scientific fields, the presence of water molecules usually affects the operation and quality of the system.

[0004] The current SF6 circuit breaker cannot monitor the water density in GIS in real time, nor can it give an alarm in time when SF6 insulating gas leaks, which may cause the circuit breaker to fail to operate normally. Circuit breakers play an important role in protection and control in power systems. Once a failure occurs, it may cause huge economic losses.

[0005] The wireless micro-water density monitoring system disclosed in the patent application with reference publication number CN203643429U directly uploads the measured SF6 density and micro-water density data to the data collector by using a wireless data transmission system, and then uploads them to the server and monitoring host through the data collector, thereby realizing remote real-time monitoring and reducing the difficulty of construction wiring.

[0006] A comprehensive analysis of the above patents reveals the following defects:

[0007] At present, the micro-water density monitoring system usually directly obtains the SF6 gas in the circuit breaker for detection during the monitoring process. The micro-water density of SF6 gas can be detected when the micro-water density monitoring system can work normally. However, the micro-water density monitoring system is prone to failure after working for a long time, and it is impossible to find the failure in time and repair it, resulting in the output SF6 gas micro-water density detection result cannot accurately feedback the real state of SF6 gas micro-water density, and cannot accurately judge the real working environment of the circuit breaker, thus making the operation of the power system in a dangerous state;

[0008] Secondly, the SF6 gas pressure in the main gas chamber of the circuit breaker is often obtained only through a single pressure sensor. When the pressure sensor fails, it is easy to cause inaccurate pressure data acquisition, which can easily lead to misjudgment of the working environment of the main gas chamber of the circuit breaker and affect the stable operation of the circuit breaker.

[0009] Therefore, the present invention proposes an online monitoring system for micro-water density to solve the above problems. Summary of the invention

[0010] In view of the deficiencies in the prior art, the present invention provides an online monitoring system for micro-water density, which solves the problem that the micro-water density monitoring system is prone to malfunction after working for a long time, and the malfunction cannot be discovered and repaired in time, resulting in the output SF6 gas micro-water density detection result being unable to accurately feedback the true state of the SF6 gas micro-water density, and unable to accurately judge the true working environment of the circuit breaker, thereby putting the operation of the power system in a dangerous state; the SF6 gas pressure in the main gas chamber of the circuit breaker is often obtained only through a single pressure sensor. After the pressure sensor fails, it is easy to cause inaccurate pressure data acquisition, thereby easily resulting in misjudgment of the working environment of the main gas chamber of the circuit breaker, affecting the stable operation of the circuit breaker.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions: a micro-water density online monitoring system, comprising:

[0012] The data acquisition unit is used to obtain the micro-water density, gas pressure and gas temperature data of SF6 gas in the circuit breaker, providing data support for online monitoring and analysis of micro-water density;

[0013] The analysis and judgment unit is used to analyze and judge the water density, gas pressure and gas temperature data collected by the data acquisition unit to determine that the water density of SF6 gas is within a safe value range and there is no gas leakage;

[0014] The analog monitoring unit is used to perform a self-test of the micro-water density online monitoring system before testing the micro-water density of SF6 gas in the main gas chamber of the circuit breaker to determine the integrity of the micro-water density online monitoring system function;

[0015] Microcirculation system, used to quickly balance the humidity of the circuit breaker main air chamber and the sampling point, ensuring that online measurement accurately reflects the humidity of the main air chamber;

[0016] Life assessment module, used to assess and predict the service life of the circuit breaker;

[0017] The temperature change recording module is used to record the SF6 gas temperature data in the main gas chamber of the circuit breaker when the temperature exceeds the working temperature limit, providing data support for the work of the life assessment module;

[0018] The verification unit is used to reversely calculate the theoretical value corresponding to the micro-water density in the gas chamber of the SF6 circuit breaker according to the SF6 gas pressure data collected by the data acquisition unit, and judge the working state of the data acquisition unit by judging the theoretical value and the micro-water density value actually measured in the gas chamber of the SF6 circuit breaker;

[0019] A control unit, used to control the entire micro-water density online monitoring system;

[0020] The background monitoring system displays and stores data in real time, and completes the diagnosis of the switch status based on the status information of SF6 gas.

[0021] Furthermore, it also includes: a communication module, through which the control unit establishes wireless network communication with the background monitoring system, for transmitting real-time monitoring data of SF6 gas to the background monitoring system;

[0022] A storage module, used to store the SF6 gas micro-water density, gas pressure and gas temperature data collected by the data acquisition unit;

[0023] Early warning module, used for sound and light alarm when any of the SF6 gas water density, gas pressure or gas temperature data is abnormal;

[0024] The transmitter is used to convert the physical quantity signal collected by the data acquisition unit into a current or voltage signal for transmission and processing.

[0025] Furthermore, the data acquisition unit includes a micro-water density sensor, a gas pressure sensor, a gas temperature sensor and a gas density sensor, which are used to detect the micro-water density, gas pressure, gas temperature and gas density data of SF6 gas respectively.

[0026] Furthermore, the simulation monitoring unit includes a preset enclosed space of a fixed known volume, and a preset SF6 gas is arranged in the enclosed space. The micro-water density, gas pressure, gas density and gas temperature values ​​in the enclosed space are the same as the operating conditions of the circuit breaker main chamber under normal working conditions, and are all known values.

[0027] Furthermore, the analysis and judgment steps of the analysis and judgment unit are:

[0028] Sa1, obtain SF6 gas sample data, and determine whether the micro-water density in the SF6 sample gas is the sample preset value ρ1. If it is the same as the SF6 gas sample micro-water density preset value ρ1, the micro-water density online monitoring system is in normal operating state, otherwise the micro-water density online monitoring system is in fault state;

[0029] Sa2. After confirming that the micro-water density online monitoring system is operating normally, obtain the micro-water density data ρ2 in the SF6 gas in the main gas chamber of the circuit breaker and sort out the data to determine whether the micro-water density ρ2 in the SF6 gas is less than 500ppm. If not, the circuit breaker is in a dangerous state. If yes, proceed to the next step to detect the SF6 gas pressure value P1;

[0030] Sa3. When detecting the SF6 gas pressure value P1, two detection methods are used to simultaneously detect the SF6 gas pressure value to ensure the accuracy of the detection;

[0031] Method 1: Obtain the SF6 gas density data of previous years and draw a curve. Take any two points A and B on the drawn curve and calculate the slope K of the line between points A and B.

[0032] The coordinates of points A and B are (Ax, Ay) and (Bx, By) respectively, then the slope of the line is calculated by the following formula: Slope K = (By-Ay) / (Bx-Ax);

[0033] Method 2: directly obtain the SF6 gas pressure value P1 of the main gas chamber of the circuit breaker, and judge whether the SF6 gas pressure is between the reasonable range of 0.3 and 0.8 MPa. If not, the main gas chamber of the circuit breaker is leaking and it is in a dangerous working state. If yes, the SF6 gas pressure value of the circuit breaker is normal and the working state is safe.

[0034] Sa4. Obtain the SF6 gas temperature T1 in the main gas chamber of the circuit breaker, and determine whether the SF6 gas temperature T1 value is in the range of -40°C to +40°C. If not, the SF6 gas temperature in the main gas chamber of the circuit breaker is abnormal and it is in a dangerous working state. If yes, the SF6 gas temperature T1 in the main gas chamber of the circuit breaker is normal.

[0035] Furthermore, in the step Sa3, it is determined whether the slope K of the line between points A and B is a negative value. If K is a negative value, the line between points A and B is inclined downward, that is, the SF6 gas density is gradually decreasing, the SF6 gas pressure is gradually decreasing, and leakage occurs in the main gas chamber of the circuit breaker. If the slope K is 0, the line between points A and B is horizontal, the SF6 gas density does not change, that is, the SF6 gas pressure is in a stable state.

[0036] Furthermore, the simulation monitoring process of the simulation monitoring unit is:

[0037] Sb1. Before the micro-water density online monitoring system detects the micro-water density of SF6 gas in the main gas chamber of the circuit breaker, the control unit sends a command for self-checking the working status of the micro-water density online monitoring system to the analog monitoring unit;

[0038] Sb2, the data acquisition module collects the preset micro-water density of SF6 gas, which is used to analyze and determine whether the working state of the micro-water density online monitoring system is a normal working state or a fault state;

[0039] Sb3. The analysis and judgment unit detects the micro-water density of the collected preset SF6 sample gas, and compares the difference between the micro-water density detection value of the SF6 sample gas and the preset value. If the detection value of the micro-water density is equal to the preset value or infinitely close to the preset value, the micro-water density online monitoring system is in normal working state. Otherwise, when the detection value of the micro-water density exceeds the allowable error, the circuit breaker is in a fault state.

[0040] Furthermore, the working process of the verification unit specifically includes the following steps:

[0041] Sc1. Record the change in the air chamber pressure, that is, the difference from the original air pressure X value to the air pressure Y value, recorded as ΔP = XY;

[0042] Sc2. Normally, the gas temperature in the SF6 circuit breaker fluctuates between 20℃ and 40℃. Select an intermediate value as the gas temperature T for calculation;

[0043] Sc3. Calculate the number of moles of SF6 gas in the gas chamber n according to the ideal gas state equation PV=nRT, where P is the gas chamber pressure, V is the gas chamber volume, R is the gas constant, and T is the gas temperature;

[0044] When the gas chamber pressure is X value, the number of moles of SF6 gas n1 = XV / RT;

[0045] When the gas chamber pressure is Y value, the number of moles of SF6 gas n2 = YV / RT;

[0046] Sc4. The relationship between the number of moles of gas and its mass is expressed as n = m / M, where m is the mass of the gas and M is the molar mass of the gas.

[0047] When the gas chamber pressure is X value, the mass of SF6 gas m1 = (XV / RT)*M;

[0048] When the gas chamber pressure is Y value, the mass of SF6 gas m2 = (YV / RT)*M;

[0049] Δm = m1-m2, which is the mass of SF6 gas lost when the circuit breaker gas chamber leaks;

[0050] Sc5. When the gas chamber pressure is Y value, the SF6 gas density ρ of the SF6 circuit breaker gas chamber collected by the data acquisition unit SF6 , that is, at this time, the SF6 gas mass m3 = ρ SF6 *v, where V is the volume of the gas chamber, and the data acquisition unit is sensitive to the SF6 gas density ρSF6 The allowable error of acquisition is denoted as ρ SF6 ±j, that is, the error range of m3 is m3±j. When the value of m2 is closer to m3, the error is smaller, which means that the data acquisition accuracy of the data acquisition unit is higher, and the estimated length of its service life is longer. Conversely, if the value of m2 is closer to the absolute value of ρSF6+j or ρSF6-j, the error is larger, and the data acquisition accuracy of the data acquisition unit is lower, and the estimated length of its service life is shorter, requiring staff to repair or replace some sensors in the data acquisition unit in a short time.

[0051] Furthermore, the working process of the life assessment module specifically includes the following steps:

[0052] Sd1, obtain the data of the historical temperature C of the main gas chamber of the circuit breaker, and judge whether the current historical abnormal temperature data value C of the main gas chamber is greater than the theoretical working temperature limit value C1. If so, proceed to the next step of judgment; otherwise, continue to obtain the historical abnormal temperature data value C of the main gas chamber of the circuit breaker and compare it with the working temperature limit value C1;

[0053] Sd2, after the historical abnormal temperature data value C of the main gas chamber of the circuit breaker obtained in step S1 is greater than the working temperature limit value C1, it is determined whether the duration of the current historical abnormal temperature data value C of the circuit breaker being greater than the working temperature limit value C1 is greater than μ, and if so, it is recorded as an ultra-high temperature working of the main gas chamber f;

[0054] Sd3. Determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval δ. If so, the remaining service life of the circuit breaker is estimated to be α through the number of ultra-high temperature working times F of the main gas chamber. Otherwise, determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval Φ. If so, the remaining service life of the circuit breaker is estimated to be β. Otherwise, determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval Ψ. If so, the remaining service life of the circuit breaker is estimated to be γ. Otherwise, continue to obtain the historical abnormal temperature data value C of the main gas chamber for judgment one by one.

[0055] The present invention provides an online monitoring system for micro-water density. Compared with the prior art, it has the following beneficial effects:

[0056] 1. A micro-water density online monitoring system, by setting an analysis and judgment unit and a simulation monitoring unit, can use the preset SF6 gas as verification data before the data acquisition unit works. Since the preset SF6 gas micro-water density, gas density, gas pressure and gas temperature are all preset values, they are respectively transported to the micro-water density sensor, gas density sensor, gas pressure sensor and gas temperature sensor through a microcirculation system. By comparing the data detected by the sensor with the preset values ​​of SF6 gas, the difference between the detection value and the preset value is analyzed and judged, so that the working state of each sensor can be analyzed, and whether there is a detection fault in any sensor can be found in time, and the fault can be found and eliminated before the micro-water density online monitoring system works, so as to avoid the situation that the micro-water density online monitoring system outputs wrong micro-water density detection data due to its own fault when working, and improve the accuracy of the detection result of the micro-water density online monitoring system.

[0057] 2. A micro-water density online monitoring system, by setting a verification unit, can obtain the current air pressure in the main gas chamber of the circuit breaker through a gas pressure sensor, and can calculate the mass of the SF6 gas in the main gas chamber of the current circuit breaker according to the ideal gas state equation. At the same time, combined with the SF6 gas density value of the main gas chamber of the circuit breaker measured by the gas density sensor, the mass of the SF6 gas can also be calculated. By comparing the SF6 gas mass calculated using the SF6 gas pressure value and the SF6 gas mass directly calculated using the SF6 gas density, it is possible to mutually verify whether the gas pressure sensor and the gas density sensor are in normal working condition, thereby avoiding the situation where the monitoring result is inaccurate due to the abnormal operation of the monitoring system, thereby improving the accuracy and credibility of the monitoring result.

[0058] 3. A micro-water density online monitoring system, by setting a gas density sensor, can obtain the SF6 gas density data in the main gas chamber of the circuit breaker over the years, and draw the gas density data into a curve. By judging the positive and negative values ​​of the slope of the line between any two points on the SF6 gas density curve, it can be judged whether the SF6 gas density has changed, making the judgment process of the circuit breaker detection result more intuitive, that is, when the slope is negative, according to the formula between density, volume and mass, it can be judged that the gas mass in the main gas chamber of the circuit breaker has decreased, and the main gas chamber of the circuit breaker has leaked, so as to remind the staff to carry out maintenance in time, so as to achieve the purpose of feedback on the working condition of the circuit breaker from the side.

[0059] 4. A micro-water density online monitoring system, by setting up a life assessment module and a temperature change recording module, can obtain the historical abnormal temperature data of the main air chamber of the circuit breaker, and by judging the number of times the historical abnormal temperature data value exceeds the operating temperature limit of the circuit breaker and the duration of the circuit breaker exceeding the operating temperature limit, it can predict the remaining service life of the circuit breaker based on the big data of the actual service life of the circuit breaker, which is conducive to prompting the staff to inspect and replace the circuit breaker in time to ensure that the circuit is always in a safe and protected state. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a system structure block diagram of the present invention;

[0061] Figure 2 This is an operation flow chart of the analysis and judgment unit of the present invention;

[0062] Figure 3 This is an operation flow chart of the life assessment module of the present invention. DETAILED DESCRIPTION

[0063] 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.

[0064] like Figures 1 to 3 The present invention provides four technical solutions: a micro-water density online monitoring system, specifically including the following embodiments:

[0065] Embodiment 1: A micro-water density online monitoring system, comprising:

[0066] The data acquisition unit is used to obtain the micro-water density, gas pressure and gas temperature data of SF6 gas in the circuit breaker, providing data support for online monitoring and analysis of micro-water density;

[0067] The analysis and judgment unit is used to analyze and judge the water density, gas pressure and gas temperature data collected by the data acquisition unit to determine that the water density of SF6 gas is within a safe value range and there is no gas leakage;

[0068] The analog monitoring unit is used to perform a self-test of the micro-water density online monitoring system before testing the micro-water density of SF6 gas in the main gas chamber of the circuit breaker to determine the integrity of the micro-water density online monitoring system function;

[0069] Microcirculation system, used to quickly balance the humidity of the circuit breaker main air chamber and the sampling point, ensuring that online measurement can accurately reflect the humidity of the main air chamber;

[0070] Life assessment module, used to assess and predict the service life of the circuit breaker;

[0071] The temperature change recording module is used to record the SF6 gas temperature data in the main gas chamber of the circuit breaker when the temperature exceeds the working temperature limit, providing data support for the work of the life assessment module;

[0072] The verification unit is used to reversely calculate the theoretical value corresponding to the micro-water density in the gas chamber of the SF6 circuit breaker according to the SF6 gas pressure data collected by the data acquisition unit, and judge the working state of the data acquisition unit by judging the theoretical value and the micro-water density value actually measured in the gas chamber of the SF6 circuit breaker;

[0073] A control unit, used to control the entire micro-water density online monitoring system;

[0074] The background monitoring system displays and stores data in real time, and completes the diagnosis of the switch status based on the status information of SF6 gas.

[0075] In the embodiment of the present invention, it also includes: a communication module, the control unit establishes wireless network communication with the background monitoring system through the communication module, and is used to transmit real-time monitoring data of SF6 gas to the background monitoring system;

[0076] A storage module, used to store the SF6 gas micro-water density, gas pressure and gas temperature data collected by the data acquisition unit;

[0077] Early warning module, used for sound and light alarm when any of the SF6 gas water density, gas pressure or gas temperature data is abnormal;

[0078] The transmitter is used to convert the physical quantity signal collected by the data acquisition unit into a current or voltage signal for transmission and processing.

[0079] In the embodiment of the present invention, the data acquisition unit includes a micro-water density sensor, a gas pressure sensor, a gas temperature sensor and a gas density sensor, which are respectively used to detect the micro-water density, gas pressure, gas temperature and gas density data of SF6 gas.

[0080] The simulation monitoring unit includes a preset enclosed space with a fixed known volume, and a preset SF6 gas is set in the enclosed space. The water density, gas pressure, gas density and gas temperature values ​​in the enclosed space are the same as the working conditions of the main chamber of the circuit breaker under normal working conditions, and are all known values. The SF6 gas under this working condition is called the SF6 gas preset value.

[0081] Embodiment 2: The main difference between this embodiment and the first technical solution is that: an online monitoring system for micro-water density, the analysis and judgment steps of the analysis and judgment unit are:

[0082] Sa1, obtain SF6 gas sample data, and determine whether the micro-water density in the SF6 sample gas is the sample preset value ρ1. If it is the same as the SF6 gas sample micro-water density preset value ρ1, the micro-water density online monitoring system is in normal operating state, otherwise the micro-water density online monitoring system is in fault state;

[0083] Sa2. After confirming that the micro-water density online monitoring system is operating normally, obtain the micro-water density data ρ2 in the SF6 gas in the main gas chamber of the circuit breaker and sort out the data to determine whether the micro-water density ρ2 in the SF6 gas is less than 500ppm. If not, the circuit breaker is in a dangerous state. If yes, proceed to the next step to detect the SF6 gas pressure value P1;

[0084] Sa3. When detecting the SF6 gas pressure value P1, two detection methods are used to simultaneously detect the SF6 gas pressure value to ensure the accuracy of the detection;

[0085] Method 1: Obtain the SF6 gas density data of previous years and draw a curve. Take any two points A and B on the drawn curve and calculate the slope K of the line between points A and B.

[0086] The coordinates of points A and B are (Ax, Ay) and (Bx, By) respectively, then the slope of the line can be calculated by the following formula: Slope K = (By-Ay) / (Bx-Ax);

[0087] Method 2: directly obtain the SF6 gas pressure value P1 of the main gas chamber of the circuit breaker, and judge whether the SF6 gas pressure is between the reasonable range of 0.3 and 0.8 MPa. If not, the main gas chamber of the circuit breaker is leaking and it is in a dangerous working state. If yes, the SF6 gas pressure value of the circuit breaker is normal and the working state is safe.

[0088] Sa4. Obtain the SF6 gas temperature T1 in the main gas chamber of the circuit breaker, and determine whether the SF6 gas temperature T1 value is in the range of -40°C to +40°C. If not, the SF6 gas temperature in the main gas chamber of the circuit breaker is abnormal and it is in a dangerous working state. If yes, the SF6 gas temperature T1 in the main gas chamber of the circuit breaker is normal.

[0089] In step Sa3, determine whether the slope K of the line between points A and B is a negative value. If K is a negative value, the line between points A and B is inclined downward, that is, the SF6 gas density is gradually decreasing, the SF6 gas pressure is gradually decreasing, and leakage occurs in the main gas chamber of the circuit breaker. If the slope K is 0, the line between points A and B is horizontal, the SF6 gas density does not change, that is, the SF6 gas pressure is in a stable state. The normal working pressure of SF6 gas is between 0.3 and 0.8 MPa. If the pressure of SF6 gas exceeds 0.8 MPa, it will cause overload and danger of equipment; the normal working temperature of SF6 gas is between -40℃ and +40℃. If the temperature of SF6 gas exceeds this range, it will affect the insulation performance of the circuit breaker or cause equipment failure.

[0090] Judgment criteria for the water density in SF6 gas in circuit breakers: When the water density in SF6 gas is less than 500ppm, it is in good condition.

[0091] In the embodiment of the present invention, the simulation monitoring process of the simulation monitoring unit is as follows:

[0092] Sb1. Before the micro-water density online monitoring system detects the micro-water density of SF6 gas in the main gas chamber of the circuit breaker, the control unit sends a command for self-checking the working status of the micro-water density online monitoring system to the analog monitoring unit;

[0093] Sb2, the data acquisition module collects the preset micro-water density of SF6 gas, which is used to analyze and determine whether the working state of the micro-water density online monitoring system is a normal working state or a fault state;

[0094] Sb3. The analysis and judgment unit detects the micro-water density of the collected preset SF6 sample gas, and compares the difference between the micro-water density detection value of the SF6 sample gas and the preset value. If the detection value of the micro-water density is equal to the preset value or infinitely close to the preset value, the micro-water density online monitoring system is in normal working state. Otherwise, when the detection value of the micro-water density exceeds the allowable error, the circuit breaker is in a fault state.

[0095] Embodiment 3: The main difference between this embodiment and the second technical solution is that: a micro-water density online monitoring system, the working process of the verification unit specifically includes the following steps:

[0096] Sc1. Record the change in the air chamber pressure, that is, the difference from the original air pressure X value to the air pressure Y value, recorded as ΔP = XY (in kPa);

[0097] Sc2. Normally, the gas temperature in the SF6 circuit breaker fluctuates between 20°C and 40°C. Select an intermediate value as the gas temperature T (in degrees Celsius) for calculation;

[0098] Sc3. Calculate the number of moles n of SF6 gas in the gas chamber according to the ideal gas state equation PV=nRT, where P is the gas chamber pressure, V is the gas chamber volume, R is the gas constant (valued at 8.314 J / (mol·K)), and T is the gas temperature;

[0099] When the gas chamber pressure is X value, the number of moles of SF6 gas n1 = XV / RT;

[0100] When the gas chamber pressure is Y value, the number of moles of SF6 gas n2 = YV / RT;

[0101] Sc4, the relationship between the number of gas moles and mass is expressed as n = m / M, where m is the mass of the gas (in kilograms), and M is the molar mass of the gas (the molar mass of SF6 is about 146.05 g / mol).

[0102] When the gas chamber pressure is X value, the mass of SF6 gas m1 = (XV / RT)*M;

[0103] When the gas chamber pressure is Y value, the mass of SF6 gas m2 = (YV / RT)*M;

[0104] Δm = m1-m2, which is the mass of SF6 gas lost when the circuit breaker gas chamber leaks;

[0105] Sc5. When the gas chamber pressure is Y value, the SF6 gas density ρ of the SF6 circuit breaker gas chamber collected by the data acquisition unit SF6 , that is, at this time, the SF6 gas mass m3 = ρ SF6 *v, where V is the volume of the gas chamber, and the data acquisition unit is sensitive to the SF6 gas density ρ SF6 The allowable error of acquisition is denoted as ρ SF6 ±j, that is, the error range of m3 is m3±j. When the value of m2 is closer to m3, the error is smaller, which means that the data acquisition accuracy of the data acquisition unit is higher, and the estimated length of its service life is longer. On the contrary, if the value of m2 is closer to ρ SF6 +j or ρ SF6 -j, the larger the error is, the lower the data acquisition accuracy of the data acquisition unit is, and the shorter the estimated length of its service life is, requiring the staff to repair or replace some sensors in the data acquisition unit in a short period of time.

[0106] Embodiment 4: The main difference between this embodiment and the third technical solution is that: a micro-water density online monitoring system, the working process of the life assessment module specifically includes the following steps:

[0107] Sd1, obtain the data of the historical temperature C of the main air chamber of the circuit breaker, and judge whether the current historical abnormal temperature data value C of the main air chamber is greater than the theoretical working temperature limit value C1. If so, proceed to the next step of judgment, otherwise, continue to obtain the historical abnormal temperature data value C of the main air chamber of the circuit breaker and the working temperature limit value C1 for size comparison. Among them, the working temperature limit value C1 is generally 60℃, and the size of the working temperature limit value C1 shall be based on the actual setting value of the circuit breaker manufacturer;

[0108] Sd2, after the historical abnormal temperature data value C of the main gas chamber of the circuit breaker obtained in step Sd1 is greater than C1, determine whether the duration of the current historical abnormal temperature data value C of the circuit breaker being greater than the working temperature limit value C1 is greater than μ, if so, record it as an ultra-high temperature working time of the main gas chamber;

[0109] Sd3. Determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval δ. If so, the remaining service life of the circuit breaker is estimated to be α through the number of ultra-high temperature working times F of the main gas chamber. Otherwise, determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval Φ. If so, the remaining service life of the circuit breaker is estimated to be β. Otherwise, determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval Ψ. If so, the remaining service life of the circuit breaker is estimated to be γ. Otherwise, continue to obtain the historical abnormal temperature data value C of the main gas chamber for judgment one by one. Among them, the value range of δ interval is: δ∈〔3,5〕, the value range of α interval is: α∈〔2,3〕, the value range of Φ interval is: Φ∈〔6,8〕, the value range of β interval is: β∈〔1,1.5〕, the value range of Ψ interval is: Ψ∈〔9,12〕, and the value range of γ interval is: γ∈〔0.5,0.8〕, where the units of α, β, and γ are years, and the units of δ, Φ, and Ψ are times.

[0110] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0111] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A micro-water density online monitoring system, characterized in that: include: The data acquisition unit is used to obtain the micro-water density, gas pressure and gas temperature data of SF6 gas in the circuit breaker, providing data support for online monitoring and analysis of micro-water density; The analysis and judgment unit is used to analyze and judge the water density, gas pressure and gas temperature data collected by the data acquisition unit to determine that the water density of SF6 gas is within a safe value range and there is no gas leakage; The analog monitoring unit is used to perform a self-test of the micro-water density online monitoring system before testing the micro-water density of SF6 gas in the main gas chamber of the circuit breaker to determine the integrity of the micro-water density online monitoring system function; Microcirculation system, used to quickly balance the humidity of the circuit breaker main air chamber and the sampling point, ensuring that online measurement accurately reflects the humidity of the main air chamber; Life assessment module, used to assess and predict the service life of the circuit breaker; The temperature change recording module is used to record the SF6 gas temperature data in the main gas chamber of the circuit breaker when the temperature exceeds the working temperature limit, providing data support for the work of the life assessment module; The verification unit is used to reversely calculate the theoretical value corresponding to the micro-water density in the gas chamber of the SF6 circuit breaker according to the SF6 gas pressure data collected by the data acquisition unit, and judge the working state of the data acquisition unit by judging the theoretical value and the micro-water density value actually measured in the gas chamber of the SF6 circuit breaker; A control unit, used to control the entire micro-water density online monitoring system; The background monitoring system displays and stores data in real time, and completes the diagnosis of the switch status based on the status information of SF6 gas; The analysis and judgment steps of the analysis and judgment unit are: Sa1, obtain SF6 gas sample data, and determine whether the micro-water density in the SF6 sample gas is the sample preset value ρ1. If it is the same as the SF6 gas sample micro-water density preset value ρ1, the micro-water density online monitoring system is in normal operating state, otherwise the micro-water density online monitoring system is in fault state; Sa2. After confirming that the micro-water density online monitoring system is operating normally, obtain the micro-water density data ρ2 in the SF6 gas in the main gas chamber of the circuit breaker and sort out the data to determine whether the micro-water density ρ2 in the SF6 gas is less than 500ppm. If not, the circuit breaker is in a dangerous state. If yes, proceed to the next step to detect the SF6 gas pressure value P1; Sa3. When detecting the SF6 gas pressure value P1, two detection methods are used to simultaneously detect the SF6 gas pressure value to ensure the accuracy of the detection; Method 1: Obtain the SF6 gas density data of previous years and draw a curve. Take any two points A and B on the drawn curve and calculate the slope K of the line between points A and B. The coordinates of points A and B are (Ax, Ay) and (Bx, By) respectively, then the slope of the line is calculated by the following formula: Slope K = (By-Ay) / (Bx-Ax); Method 2: directly obtain the SF6 gas pressure value P1 of the main gas chamber of the circuit breaker, and judge whether the SF6 gas pressure is between the reasonable range of 0.3 and 0.8 MPa. If not, the main gas chamber of the circuit breaker is leaking and it is in a dangerous working state. If yes, the SF6 gas pressure value of the circuit breaker is normal and the working state is safe. Sa4. Obtain the SF6 gas temperature T1 in the main gas chamber of the circuit breaker, and determine whether the SF6 gas temperature T1 value is within the range of -40°C to +40°C. If not, the SF6 gas temperature in the main gas chamber of the circuit breaker is abnormal and it is in a dangerous working state. If yes, the SF6 gas temperature T1 in the main gas chamber of the circuit breaker is normal. In the step Sa3, it is determined whether the slope K of the line between points A and B is a negative value. If K is a negative value, the line between points A and B is inclined downward, that is, the SF6 gas density is gradually decreasing, the SF6 gas pressure is gradually decreasing, and leakage occurs in the main gas chamber of the circuit breaker. If the slope K is 0, the line between points A and B is horizontal, the SF6 gas density does not change, that is, the SF6 gas pressure is in a stable state.

2. The micro-water density online monitoring system according to claim 1, characterized in that: Also includes: Communication module: the control unit establishes wireless network communication with the background monitoring system through the communication module, and is used to transmit real-time monitoring data of SF6 gas to the background monitoring system; A storage module, used to store the SF6 gas micro-water density, gas pressure and gas temperature data collected by the data acquisition unit; Early warning module, used for sound and light alarm when any of the SF6 gas water density, gas pressure or gas temperature data is abnormal; The transmitter is used to convert the physical quantity signal collected by the data acquisition unit into a current or voltage signal for transmission and processing.

3. The micro-water density online monitoring system according to claim 1 is characterized in that: The data acquisition unit includes a micro-water density sensor, a gas pressure sensor, a gas temperature sensor and a gas density sensor, which are used to detect the micro-water density, gas pressure, gas temperature and gas density data of SF6 gas respectively.

4. The micro-water density online monitoring system according to claim 1, characterized in that: The simulation monitoring unit includes a preset enclosed space with a fixed known volume, and a preset SF6 gas is arranged in the enclosed space. The trace water density, gas pressure, gas density and gas temperature values ​​in the enclosed space are the same as the operating conditions of the main chamber of the circuit breaker under normal working conditions, and are all known values.

5. The micro-water density online monitoring system according to claim 1 is characterized in that: The simulation monitoring process of the simulation monitoring unit is as follows: Sb1. Before the micro-water density online monitoring system detects the micro-water density of SF6 gas in the main gas chamber of the circuit breaker, the control unit sends a command for self-checking the working status of the micro-water density online monitoring system to the analog monitoring unit; Sb2, the data acquisition module collects the preset micro-water density of SF6 gas, which is used to analyze and determine whether the working state of the micro-water density online monitoring system is a normal working state or a fault state; Sb3. The analysis and judgment unit detects the micro-water density of the collected preset SF6 sample gas, and compares the difference between the micro-water density detection value of the SF6 sample gas and the preset value. If the detection value of the micro-water density is equal to the preset value or infinitely close to the preset value, the micro-water density online monitoring system is in normal working state. Otherwise, when the detection value of the micro-water density exceeds the allowable error, the circuit breaker is in a fault state.

6. The micro-water density online monitoring system according to claim 1 is characterized in that: The working process of the verification unit specifically includes the following steps: Sc1. Record the change in the air chamber pressure, that is, the difference from the original air pressure X value to the air pressure Y value, recorded as ΔP = XY; Sc2. Normally, the gas temperature in the SF6 circuit breaker fluctuates between 20℃ and 40℃. Select an intermediate value as the gas temperature T for calculation; Sc3. Calculate the number of moles of SF6 gas in the gas chamber n according to the ideal gas state equation PV=nRT, where P is the gas chamber pressure, V is the gas chamber volume, R is the gas constant, and T is the gas temperature; When the chamber pressure is X value, the number of moles of SF6 gas n1 = XV / RT; When the gas chamber pressure is Y value, the number of moles of SF6 gas n2 = YV / RT; Sc4. The relationship between the number of moles of gas and its mass is expressed as n = m / M, where m is the mass of the gas and M is the molar mass of the gas. When the gas chamber pressure is X value, the mass of SF6 gas m1 = (XV / RT)*M; When the gas chamber pressure is Y value, the mass of SF6 gas m2 = (YV / RT)*M; Δm = m1-m2, which is the mass of SF6 gas lost when the circuit breaker gas chamber leaks; Sc5. When the gas chamber pressure is Y value, the SF6 gas density ρ of the SF6 circuit breaker gas chamber collected by the data acquisition unit SF6 , that is, at this time, the SF6 gas mass m3 = ρ SF6 *v, where V is the volume of the gas chamber, and the data acquisition unit is sensitive to the SF6 gas density ρ SF6 The allowable error of acquisition is denoted as ρ SF6 ±j, that is, the error range of m3 is m3±j. When the value of m2 is closer to m3, the error is smaller, which means that the data acquisition accuracy of the data acquisition unit is higher, and the estimated length of its service life is longer. On the contrary, if the value of m2 is closer to ρ SF6 +j or ρ SF6 -j, the larger the error is, the lower the data acquisition accuracy of the data acquisition unit is, and the shorter the estimated length of its service life is, requiring the staff to repair or replace some sensors in the data acquisition unit in a short period of time.

7. The micro-water density online monitoring system according to claim 1 is characterized in that: The working process of the life assessment module specifically includes the following steps: Sd1, obtain the data of the historical temperature C of the main gas chamber of the circuit breaker, and judge whether the current historical abnormal temperature data value C of the main gas chamber is greater than the theoretical working temperature limit value C1. If so, proceed to the next step of judgment; otherwise, continue to obtain the historical abnormal temperature data value C of the main gas chamber of the circuit breaker and compare it with the working temperature limit value C1; Sd2, after the historical abnormal temperature data value C of the main gas chamber of the circuit breaker obtained in step Sd1 is greater than the working temperature limit value C1, it is determined whether the duration of the current historical abnormal temperature data value C of the circuit breaker being greater than the working temperature limit value C1 is greater than μ, and if so, it is recorded as an ultra-high temperature working of the main gas chamber f; Sd3. Determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval δ. If so, the remaining service life of the circuit breaker is estimated to be α through the number of ultra-high temperature working times F of the main gas chamber. Otherwise, determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval Φ. If so, the remaining service life of the circuit breaker is estimated to be β. Otherwise, determine whether the number of ultra-high temperature working times F of the main gas chamber is within the interval Ψ. If so, the remaining service life of the circuit breaker is estimated to be γ. Otherwise, continue to obtain the historical abnormal temperature data value C of the main gas chamber for judgment one by one.

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