Gas leakage detection method for sulfur hexafluoride ring main unit

Abstract

The present application relates to the technical field of gas leakage detection in sulfur hexafluoride ring main unit, and specifically to a gas leakage detection method for sulfur hexafluoride ring main unit, the method comprising: determining a gas concentration variation index based on the difference in variation trends between temperature data and gas concentration, and in combination with the gas concentration score; determining a pressure variation law index based on the correlation between air pressure data and temperature data; determining a gas concentration variation factor based on the gas concentration variation index and the air pressure variation law index, and detecting gas leakage in the sulfur hexafluoride ring main unit in combination with the gas concentration score. The present application aims to eliminate the interference of normal gas concentration changes caused by arc extinguishing on the gas leakage detection of the sulfur hexafluoride ring main unit, and to improve the accuracy and reliability of the gas leakage detection of the sulfur hexafluoride ring main unit.

Description

Technical Field

[0001] The present application relates to the technical field of gas leakage detection for sulfur hexafluoride ring main unit, and in particular to a gas leakage detection method for a sulfur hexafluoride ring main unit. Background Art

[0002] Sulfur hexafluoride is a colorless, odorless, non-toxic gas with excellent insulation and arc-extinguishing properties. It is widely used in high-voltage equipment and ring main units in the power industry. Due to its good insulation and stability, it is used to ensure the stable operation of power equipment. However, sulfur hexafluoride gas itself is a strong greenhouse gas, and its greenhouse effect is 23,000 times that of carbon dioxide. Sulfur hexafluoride gas is used as an insulation and arc-extinguishing medium for ring main units. Gas leakage will reduce the insulation capacity of the equipment, thereby affecting the safe and stable operation of the equipment, increasing the risk of failure, and posing a greater threat to the environment.

[0003] Infrared sensors are usually used to monitor the sulfur hexafluoride gas concentration of the ring main unit online, and the risk of gas leakage is determined by analyzing the change in gas concentration. However, the main functions of sulfur hexafluoride in the ring main unit are insulation and arc extinguishing. The normal decrease in sulfur hexafluoride gas concentration caused by the decomposition of sulfur hexafluoride gas during the arc extinguishing process will interfere with the detection of sulfur hexafluoride ring main unit gas leakage, thereby reducing the accuracy and reliability of sulfur hexafluoride ring main unit gas leakage detection. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a gas leakage detection method for a sulfur hexafluoride ring main unit to solve the existing problems.

[0005] The gas leakage detection method for sulfur hexafluoride ring main unit of the present application adopts the following technical scheme:

[0006] An embodiment of the present application provides a gas leakage detection method for a sulfur hexafluoride ring main unit, the method comprising the following steps:

[0007] Obtain the gas concentration, pressure data and temperature data at all collection times in the sulfur hexafluoride ring main unit at the current time and within the preset time period before;

[0008] Based on the changes in gas concentration at all acquisition moments, all arc extinguishing time periods are determined, and based on the difference in the change trend between all temperature data and gas concentration in each arc extinguishing time period, the gas heat absorption rate of each arc extinguishing time period is determined, and combined with the difference in the change trend between the temperature data and the gas concentration in the preset time period before the current moment and adjacent to the current moment, the gas heat absorption value at the current moment is determined; based on the gas concentration score at the current moment and the gas heat absorption value, the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment is determined;

[0009] Based on the correlation between the air pressure data and the temperature data in the preset time period before the current moment and adjacent to the current moment, and the correlation between the air pressure data and the temperature data at all collection moments, determine the air pressure change law index of the sulfur hexafluoride ring main unit at the current moment;

[0010] Based on the gas concentration change index and the gas pressure change law index, the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment is determined. Combined with the gas concentration score at the current moment, the corrected standard score of the gas concentration at the current moment is determined to detect gas leakage in the sulfur hexafluoride ring main unit.

[0011] Preferably, the determining of all arc extinguishing periods comprises:

[0012] The gas concentrations at all acquisition moments before the current moment are fitted to obtain a gas concentration fitting curve, and all peaks and troughs on the gas concentration fitting curve are extracted. The time period between the acquisition moment corresponding to each peak and the acquisition moment corresponding to the adjacent trough is taken as each arc extinguishing period.

[0013] Preferably, the method for determining the gas heat absorption rate in each arc extinguishing period is:

[0014] The slope of the gas concentration fitting curve between each arc extinguishing period is obtained by linear approximation calculation, which is recorded as the first slope of each arc extinguishing period;

[0015] Fit the temperature data of all acquisition moments before the current moment to obtain a temperature fitting curve, and use linear approximation to calculate the slope of the temperature fitting curve in each arc extinguishing period, which is recorded as the second slope of each arc extinguishing period;

[0016] The gas heat absorption rate in each arc extinguishing period is determined based on the first slope and the second slope.

[0017] Preferably, determining the gas heat absorption rate in each arc extinguishing period based on the first slope and the second slope further comprises:

[0018] Gas heat absorption rate during arc extinguishing period j The expression is: ; In the formula, represents the first slope of the arc extinguishing period j; represents the second slope of the arc extinguishing period j; Represents an exponential function with a natural constant as base.

[0019] Preferably, the method for determining the gas heat absorption value at the current moment is:

[0020] The slopes of the gas concentration fitting curve and the temperature fitting curve in the preset time period before the current moment and the preset time period adjacent to the current moment are calculated by linear approximation, and are recorded as the concentration slope and temperature slope at the current moment respectively;

[0021] The difference between the concentration slope and the temperature slope at the current moment is taken as the gas difference value at the current moment;

[0022] The heat absorption value of sulfur hexafluoride ring main unit gas at the current moment The expression is: ; In the formula, Indicates the gas difference value at the current moment; It represents the mean value of the gas concentration absorption rate of all arc extinguishing periods before the current moment; exp( ) represents an exponential function with a natural constant as the base.

[0023] Preferably, the method for determining the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment is:

[0024] The gas concentration at the current moment and all previous acquisition moments is used as the input of the standardization method, and the standard fraction of the gas concentration at the current moment and each acquisition moment is output;

[0025] The gas concentration variation index of the sulfur hexafluoride ring main unit at the current moment is the product of the standard fraction of the gas concentration at the current moment and the gas heat absorption value.

[0026] Preferably, the method for determining the gas pressure variation law index of the sulfur hexafluoride ring main unit at the current moment is:

[0027] The correlation between the temperature data and the air pressure data at all the collection moments before the current moment is recorded as the overall correlation at the current moment;

[0028] Before the current moment, the correlation between the temperature data and the air pressure data at all the collected moments in the preset period adjacent to the current moment is recorded as the local correlation at the current moment;

[0029] The pressure change index of sulfur hexafluoride ring main unit at the current moment The expression is: ; In the formula, , They represent the local correlation and overall correlation at the current moment respectively; exp( ) represents an exponential function with a natural constant as the base.

[0030] Preferably, the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment is a normalized value of the product of the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment and the gas pressure change law index.

[0031] Preferably, the expression of the corrected standard fraction of the gas concentration at the current moment is: ; In the formula, Indicates the corrected standard score at the current moment; Indicates the standard fraction of gas concentration at the current moment; Indicates the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment.

[0032] Preferably, the gas leakage detection of the sulfur hexafluoride ring main unit includes:

[0033] If the corrected standard score of the gas concentration at the current moment is greater than the preset threshold, then gas leakage occurs in the sulfur hexafluoride ring main unit; otherwise, there is no gas leakage in the sulfur hexafluoride ring main unit.

[0034] This application has at least the following beneficial effects:

[0035] The present application constructs a gas concentration change index by analyzing the difference between the changing trends of gas concentration and temperature data, and combining the gas concentration score, which reflects the gas concentration change of the sulfur hexafluoride ring network cabinet at the current moment. Combined with the temperature and air pressure data, it can distinguish between the normal concentration change caused by arc extinguishing and the abnormal concentration change caused by gas leakage, and can accurately judge whether there is a risk of gas leakage and timely discover and warn of gas leakage; further, by analyzing the consistency of the changing trends between the air pressure data and the temperature values, a pressure change law index is constructed, which reflects the pressure change of the sulfur hexafluoride ring network cabinet at the current moment. Combined with the temperature and air pressure data, it can exclude the normal air pressure change caused by arc extinguishing and improve the accuracy of gas leakage detection; further, by comprehensively combining the gas concentration change index and the air pressure change law index, a gas concentration change factor is constructed, which can judge whether the gas concentration change of the ring network cabinet at the current moment is reasonable, thereby accurately judging whether there is a risk of gas leakage; the present application improves the accuracy and reliability of gas leakage detection of sulfur hexafluoride ring network cabinets by analyzing the changing trends of gas concentration, air pressure and temperature data. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A flow chart of the steps of a gas leakage detection method for a sulfur hexafluoride ring main unit provided in one embodiment of the present application;

[0038] Figure 2 A schematic diagram of a gas concentration variation factor extraction process provided for an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the gas leakage detection method for sulfur hexafluoride ring network cabinet proposed in the present application, its specific implementation method, structure, characteristics and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0040] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0041] The specific scheme of the gas leakage detection method for sulfur hexafluoride ring main unit provided by the present application is described in detail below with reference to the accompanying drawings.

[0042] An embodiment of the present application provides a gas leakage detection method for a sulfur hexafluoride ring main unit. Specifically, the following gas leakage detection method for a sulfur hexafluoride ring main unit is provided. Figure 1 , the method comprises the following steps:

[0043] Step S1: Obtain the gas concentration, pressure data and temperature data at all collection times in the sulfur hexafluoride ring main unit at the current time and within a preset time period before the current time.

[0044] Use an NDIR infrared sensor to measure the gas concentration in the sulfur hexafluoride ring network cabinet at all collection times within the preset time before the current moment; use a pressure sensor to obtain the air pressure data in the sulfur hexafluoride ring network cabinet at all collection times within the preset time before the current moment; use a temperature sensor to obtain the temperature data in the sulfur hexafluoride ring network cabinet at all collection times within the preset time before the current moment, where the data sampling frequency is set to f.

[0045] It should be noted that the values ​​of the preset duration and data sampling frequency f are manually set. In this embodiment, the preset duration is 100s and the sampling frequency f is 10Hz. The implementer can also set them according to the specific situation. This embodiment does not impose any special restrictions.

[0046] Step S2: Based on the change of gas concentration at all acquisition moments, all arc extinguishing time periods are determined, and based on the difference in the change trend between all temperature data and gas concentration in each arc extinguishing time period, the gas heat absorption rate of each arc extinguishing time period is determined, and combined with the difference in the change trend between the temperature data and the gas concentration in the preset time period before the current moment and adjacent to the current moment, the gas heat absorption value at the current moment is determined; based on the gas concentration score at the current moment and the gas heat absorption value, the gas concentration change index of the sulfur hexafluoride ring network cabinet at the current moment is determined.

[0047] Sulfur hexafluoride gas is used as an insulating and arc-extinguishing medium in the ring network cabinet. Gas leakage will reduce the insulation capacity of the equipment, thereby affecting the safe and stable operation of the equipment and increasing the risk of failure. In addition, sulfur hexafluoride gas has a long life in the atmosphere and will produce a strong greenhouse effect. The leakage of sulfur hexafluoride gas will cause great harm to the environment. Sulfur hexafluoride gas is colorless and odorless and difficult to detect. Leakage often occurs in small gaps or joints in the equipment. It may be a slow and long process. The traditional method is to use detectors regularly for manual detection. If a sudden leak occurs in the middle or a slowly accumulated leak occurs, it will cause serious harm to the environment and equipment.

[0048] In the ring main unit, when the current is interrupted, the arc will generate high temperature and strong electromagnetic interference due to the ionization phenomenon caused by high voltage or strong current, which may damage the equipment or cause a fire. Sulfur hexafluoride gas can quickly cool and suppress the arc, thereby effectively extinguishing it. During the arc extinguishing process, the concentration of sulfur hexafluoride gas will quickly decrease and react. When using standardized methods for detection, the decrease in the concentration of sulfur hexafluoride gas during the arc extinguishing process will be mistaken for a gas leak in the sulfur hexafluoride ring main unit.

[0049] Therefore, by analyzing the changing trend of the gas concentration in the sulfur hexafluoride ring main unit and the changing trend of the gas pressure data, we can accurately distinguish the normal decrease in sulfur hexafluoride gas concentration during the arc extinguishing process from the abnormal situation of sulfur hexafluoride gas leakage, and more accurately judge whether there is gas leakage in the sulfur hexafluoride ring main unit. Specifically:

[0050] S201: During the arc extinguishing process, the arc generates high temperature, and the sulfur hexafluoride gas rapidly reduces the arc temperature by absorbing heat. Therefore, when the sulfur hexafluoride gas undergoes arc decomposition reaction, causing the gas concentration to rapidly decrease, the heat absorbed by the gas temperature also decreases. According to the changing trend of the gas concentration and temperature data, the gas heat absorption value at the current moment is determined, specifically:

[0051] (1) Fit the gas concentrations at all sampling moments before the current moment to obtain a gas concentration fitting curve, and extract all peaks and troughs on the gas concentration fitting curve. The time period between the sampling moment corresponding to each peak and the sampling moment corresponding to the adjacent trough is taken as each arc extinguishing period.

[0052] It should be noted that there are many commonly used fitting methods. In this embodiment, all curve fitting processes use nonlinear least squares fitting method to fit the corresponding data. The implementer can also use other nonlinear fitting methods such as polynomial regression. This embodiment does not impose any special restrictions on the selection of fitting method.

[0053] In addition, it should be understood that the peak search algorithm is used in this embodiment to extract all peaks and troughs on the gas concentration fitting curve. The implementer may also use other methods for extracting peaks. Regarding the selection of the peak extraction method, this embodiment does not impose any special restrictions.

[0054] Among them, the nonlinear least squares method and the peak search algorithm are both well-known technologies, and the specific process of fitting the data using the nonlinear least squares method and the specific process of obtaining the peaks and troughs on the curve using the peak search algorithm will not be repeated here.

[0055] (2) The slope of the gas concentration fitting curve between each arc extinguishing period is obtained by linear approximation calculation, which is recorded as the first slope of each arc extinguishing period;

[0056] Fit the temperature data of all acquisition moments before the current moment to obtain a temperature fitting curve, and use linear approximation to calculate the slope of the temperature fitting curve in each arc extinguishing period, which is recorded as the second slope of each arc extinguishing period;

[0057] It should be noted that linear approximation refers to a method of using a linear function to approximate a general function. Linear approximation is a well-known technology, and the specific process of expressing a complex nonlinear function with a simple linear function will not be repeated here.

[0058] (3) Further, based on the first slope and the second slope, the gas heat absorption rate in each arc extinguishing period is determined, specifically:

[0059] Gas heat absorption rate during arc extinguishing period j The expression is: ; In the formula, represents the first slope of the arc extinguishing period j; represents the second slope of the arc extinguishing period j; Represents an exponential function with a natural constant as base.

[0060] According to the gas heat absorption rate in each arc extinguishing period, it can be understood that when the arc is generated, the sulfur hexafluoride gas decomposes and absorbs heat. As the gas concentration decreases over time, the temperature data also decreases. The smaller the difference between the first slope and the second slope, that is, The smaller the slope is, the greater the gas heat absorption rate during the arc extinguishing period is, which means that the greater the heat absorption rate of sulfur hexafluoride gas during the arc extinguishing process is, which means that it is more likely that the decomposition of sulfur hexafluoride gas during the arc extinguishing process caused the decrease in sulfur hexafluoride gas concentration; conversely, if the difference between the first slope and the second slope is greater, the smaller the gas heat absorption rate during the arc extinguishing period is, which means that the changing trends of gas concentration and temperature are in opposite states, and it is less likely that the decrease in sulfur hexafluoride gas concentration under normal circumstances is caused by the decomposition of sulfur hexafluoride gas during the arc extinguishing process. At this time, it is more likely that the decrease in sulfur hexafluoride gas concentration is caused by gas leakage from the sulfur hexafluoride ring main unit.

[0061] S202: Based on the gas heat absorption rate in each arc extinguishing period, and in combination with the difference in the change trend between the temperature data and the gas concentration in the preset time period before the current moment and the current moment, determine the gas heat absorption value at the current moment; based on the gas concentration score at the current moment and the gas heat absorption value, determine the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment, specifically:

[0062] (1) Using linear approximation, the slopes of the gas concentration fitting curve and the temperature fitting curve in the preset time period before the current moment and the preset time period adjacent to the current moment are calculated and recorded as the concentration slope and temperature slope at the current moment respectively;

[0063] It should be noted that the value of the preset time period is manually set. In this embodiment, the value of the preset time period is 10s. The implementer can also set it by himself according to the specific situation. This embodiment does not impose any special restrictions.

[0064] (2) Further, the difference between the concentration slope and the temperature slope at the current moment is taken as the gas difference value at the current moment;

[0065] It should be noted that there are many methods for measuring the difference between data. In this embodiment, the absolute value of the difference between the concentration slope and the temperature slope at the current moment is calculated as a way to measure the difference between the concentration slope and the temperature slope. The implementer may also use other methods such as ratios to measure the difference between data. This embodiment does not impose any special restrictions on the selection of methods for measuring the difference between data.

[0066] (3) Further, based on the gas heat absorption value of the sulfur hexafluoride ring main unit at the current moment The expression is: ; In the formula, Indicates the gas difference value at the current moment; It represents the mean value of the gas concentration absorption rate of all arc extinguishing periods before the current moment; exp( ) represents an exponential function with a natural constant as the base.

[0067] According to the gas heat absorption value of the sulfur hexafluoride ring main unit at the current moment, it can be understood that if the difference between the gas difference value at the current moment and the mean value of the gas concentration absorption rate is smaller, the gas heat absorption value is larger, indicating that the decrease in sulfur hexafluoride gas concentration at the current moment is more likely to be caused by the decomposition of sulfur hexafluoride gas during the arc extinguishing process; conversely, if the difference between the gas difference value at the current moment and the mean value of the gas concentration absorption rate is larger, the gas heat absorption value is smaller, and it is more likely that the gas concentration decrease is caused by gas leakage from the sulfur hexafluoride ring main unit.

[0068] (4) Further, the gas concentration at the current moment and all previous sampling moments is used as the input of the standardization method, and the standard score of the gas concentration at the current moment and each sampling moment is output;

[0069] It should be noted that there are many commonly used standardization methods. In this embodiment, the z-score algorithm is used to obtain the standard score of the gas concentration at each collection time. The implementer may also use other standardization methods such as the T-score algorithm. Regarding the selection of the standardization method, this embodiment does not make any special restrictions.

[0070] Among them, the z-score algorithm is a well-known technology, and the specific process of using the z-score algorithm to obtain the standard score will not be repeated.

[0071] (5) Furthermore, the product of the standard fraction of the gas concentration at the current moment and the gas heat absorption value is taken as the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment.

[0072] According to the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment, it can be understood that if the gas heat absorption value at the current moment is larger and the standard fraction of the gas concentration at the current moment is larger, it means that the change trend of the gas concentration and temperature is more consistent with the arc extinguishing process, and the gas concentration change index at the current moment is larger; conversely, if the gas heat absorption value at the current moment is smaller and the standard fraction of the gas concentration at the current moment is smaller, it means that the change trend of the gas concentration and temperature is less consistent with the arc extinguishing process, and it is more likely that the gas concentration decreases due to gas leakage from the sulfur hexafluoride ring main unit, and the gas concentration change index at the current moment is smaller.

[0073] Step S3: Based on the correlation between the air pressure data and the temperature data in the preset time period before the current moment and adjacent to the current moment, and the correlation between the air pressure data and the temperature data at all acquisition moments, determine the air pressure variation law index of the sulfur hexafluoride ring main unit at the current moment.

[0074] When using an infrared sensor to measure the concentration of sulfur hexafluoride gas in a ring main unit, the arc extinguishing reaction will generate instantaneous high temperature, and the infrared sensor relies on the detection gas to absorb infrared radiation of a specific wavelength. When the temperature rises, the movement of gas molecules intensifies, which may cause the frequency and intensity of infrared radiation absorption to change, resulting in possible deviations in the detection signal.

[0075] Therefore, in order to eliminate the influence of the normal reduction of sulfur hexafluoride gas concentration during arc extinguishing on the abnormal reduction of sulfur hexafluoride gas concentration caused by gas leakage in the sulfur hexafluoride ring main unit, the difference in the change trend between the gas pressure data and the temperature data is analyzed to accurately determine whether there is gas leakage in the sulfur hexafluoride ring main unit. Specifically:

[0076] (1) Analyze the correlation between the temperature data and the air pressure data at all the collection times before the current time, and record it as the overall correlation at the current time;

[0077] Before the current moment, the correlation between the temperature data and the air pressure data at all the collected moments in the preset period adjacent to the current moment is analyzed and recorded as the local correlation at the current moment;

[0078] It should be noted that there are many methods for measuring the correlation between data groups. In this embodiment, the correlation between temperature data and air pressure data is measured by calculating the Pearson correlation coefficient between temperature data and air pressure data at all collection moments before the current moment, and by calculating the Pearson correlation coefficient between temperature data and air pressure data at all collection moments in a preset time period before the current moment and adjacent to the current moment. The implementer may also use the Kendall rank correlation coefficient or the Spearman correlation coefficient to measure the correlation between data groups. This embodiment does not impose any special restrictions on the selection of methods for measuring the correlation between data groups.

[0079] The calculation process of the Pearson correlation coefficient is a well-known technique, and the specific calculation steps are not described in detail.

[0080] (2) Further, based on the local correlation and overall correlation, the gas pressure change law index of the sulfur hexafluoride ring main unit at the current moment is determined, specifically:

[0081] The pressure change index of sulfur hexafluoride ring main unit at the current moment The expression is: ; In the formula, , They represent the local correlation and overall correlation at the current moment respectively; exp( ) represents an exponential function with a natural constant as the base.

[0082] According to the pressure variation law index of the sulfur hexafluoride ring main unit at the current moment, it can be understood that if the degree of consistency between the pressure data and the temperature data is greater, the influence of temperature on the pressure is greater, the pressure changes with the temperature, and the difference between the local correlation and the overall correlation is smaller, the pressure change is more regular, and the pressure variation law index is larger, indicating that the temperature and pressure variation law conforms to the situation where no gas leakage occurs; conversely, if the degree of consistency between the pressure data and the temperature data is smaller, the influence of temperature on the pressure is smaller, the pressure changes with the temperature, and the difference between the local correlation and the overall correlation is larger, indicating that the pressure change is less regular, and the pressure variation law index is smaller, indicating that the probability of gas leakage in the sulfur hexafluoride ring main unit at the current moment is greater.

[0083] Step S4: Based on the gas concentration change index and the gas pressure change law index, determine the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment, and combine the gas concentration score at the current moment to determine the corrected standard score of the gas concentration at the current moment, and detect gas leakage of the sulfur hexafluoride ring main unit.

[0084] When the gas concentration change factor is smaller, the possibility that the gas concentration drop is caused by gas leakage in the sulfur hexafluoride ring main unit is very high, and the possibility of normal gas concentration change is smaller. Therefore, the standard score of the gas concentration at this time should be increased to accurately judge whether there is gas leakage in the sulfur hexafluoride ring main unit. Specifically:

[0085] The normalized value of the product of the gas concentration change index of the sulfur hexafluoride ring main unit and the gas pressure change law index at the current moment is used as the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment.

[0086] According to the gas concentration change factor of the sulfur hexafluoride ring network cabinet at the current moment, it can be understood that if the gas concentration change index at the current moment is larger, it means that the gas concentration drop is more likely to be caused by gas decomposition during the arc extinguishing process, and the larger the gas pressure change law index is, it means that the gas concentration drop is not caused by gas leakage, so when the gas concentration change index is larger and the gas pressure change law index is larger, the gas concentration change factor is larger, indicating that the possibility of gas leakage in the sulfur hexafluoride ring network cabinet at this time is smaller; conversely, if the gas concentration change index at the current moment is smaller, it means that the gas concentration drop is more likely to be caused by gas leakage in the sulfur hexafluoride ring network cabinet, and the smaller the gas pressure change law index is, it means that the gas concentration drop is more likely to be caused by gas leakage, so when the gas concentration change index is smaller and the gas pressure change law index is smaller, the gas concentration change factor is smaller, indicating that the possibility of gas leakage in the sulfur hexafluoride ring network cabinet at this time is greater.

[0087] Preferably, the schematic diagram of the gas concentration change factor extraction process provided in this embodiment is as follows: Figure 2 shown.

[0088] Furthermore, based on the gas concentration change factor and in combination with the gas concentration score at the current moment, the corrected standard score of the gas concentration at the current moment is determined, specifically:

[0089] The expression of the corrected standard fraction of gas concentration at the current moment is: ; In the formula, Indicates the corrected standard score at the current moment; Indicates the standard score of gas concentration at the current moment; Indicates the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment.

[0090] If the corrected standard score of the gas concentration at the current moment is greater than the preset threshold, then gas leakage occurs in the sulfur hexafluoride ring main unit; conversely, if the corrected standard score of the gas concentration at the current moment is less than or equal to the preset threshold, then no gas leakage occurs in the sulfur hexafluoride ring main unit.

[0091] It should be noted that the value of the preset threshold is manually set. In this embodiment, since the standardization method adopts the z-score algorithm, the value of the preset threshold is 2. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0092] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0093] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0094] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Modifications to the technical solutions recorded in the aforementioned embodiments, or equivalent replacement of some of the technical features therein, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A gas leakage detection method for a sulfur hexafluoride ring main unit, characterized in that: The method comprises the following steps: Obtain the gas concentration, pressure data and temperature data at all collection times in the sulfur hexafluoride ring main unit at the current time and within the preset time period before; Based on the changes in gas concentration at all acquisition moments, all arc extinguishing time periods are determined, and based on the difference in the change trend between all temperature data and gas concentration in each arc extinguishing time period, the gas heat absorption rate of each arc extinguishing time period is determined, and combined with the difference in the change trend between the temperature data and the gas concentration in the preset time period adjacent to the current moment, the gas heat absorption value at the current moment is determined; based on the gas concentration score at the current moment and the gas heat absorption value, the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment is determined; Based on the correlation between the air pressure data and the temperature data in the preset time period adjacent to the current moment, and the correlation between the air pressure data and the temperature data at all acquisition moments, determine the air pressure change law index of the sulfur hexafluoride ring main unit at the current moment; Based on the gas concentration change index and the gas pressure change law index, the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment is determined. Combined with the gas concentration score at the current moment, the corrected standard score of the gas concentration at the current moment is determined to detect gas leakage in the sulfur hexafluoride ring main unit.

2. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 1, characterized in that: The determining of all arc extinguishing periods comprises: The gas concentrations at all acquisition moments before the current moment are fitted to obtain a gas concentration fitting curve, and all peaks and troughs on the gas concentration fitting curve are extracted. The time period between the acquisition moment corresponding to each peak and the acquisition moment corresponding to the adjacent trough is taken as each arc extinguishing period.

3. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 2, characterized in that: The method for determining the gas heat absorption rate in each arc extinguishing period is: The slope of the gas concentration fitting curve between each arc extinguishing period is obtained by linear approximation calculation, which is recorded as the first slope of each arc extinguishing period; Fit the temperature data of all acquisition moments before the current moment to obtain a temperature fitting curve, and use linear approximation to calculate the slope of the temperature fitting curve in each arc extinguishing period, which is recorded as the second slope of each arc extinguishing period; The gas heat absorption rate in each arc extinguishing period is determined based on the first slope and the second slope.

4. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 3, characterized in that: The determining the gas heat absorption rate in each arc extinguishing period based on the first slope and the second slope further comprises: Gas heat absorption rate during arc extinguishing period j The expression is: ; In the formula, represents the first slope of the arc extinguishing period j; represents the second slope of the arc extinguishing period j; Represents an exponential function with a natural constant as base.

5. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 3, characterized in that: The method for determining the gas heat absorption value at the current moment is: The slopes of the gas concentration fitting curve and the temperature fitting curve in the preset time period adjacent to the current moment are calculated by linear approximation, and recorded as the concentration slope and temperature slope at the current moment respectively; The difference between the concentration slope and the temperature slope at the current moment is taken as the gas difference value at the current moment; The heat absorption value of sulfur hexafluoride ring main unit gas at the current moment The expression is: ; In the formula, Indicates the gas difference value at the current moment; It represents the mean value of the gas concentration absorption rate of all arc extinguishing periods before the current moment; exp( ) represents an exponential function with a natural constant as the base.

6. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 1, characterized in that: The method for determining the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment is: The gas concentration at the current moment and all previous acquisition moments is used as the input of the standardization method, and the standard fraction of the gas concentration at the current moment and each acquisition moment is output; The gas concentration variation index of the sulfur hexafluoride ring main unit at the current moment is the product of the standard fraction of the gas concentration at the current moment and the gas heat absorption value.

7. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 1, characterized in that: The method for determining the gas pressure variation law index of the sulfur hexafluoride ring main unit at the current moment is: The correlation between the temperature data and the air pressure data at all the collection moments before the current moment is recorded as the overall correlation at the current moment; The correlation between the temperature data and the air pressure data at all the collection moments in the preset period adjacent to the current moment is recorded as the local correlation at the current moment; The pressure change index of sulfur hexafluoride ring main unit at the current moment The expression is: ; In the formula, , They represent the local correlation and overall correlation at the current moment respectively; exp( ) represents an exponential function with a natural constant as the base.

8. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 1, characterized in that: The gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment is a normalized value of the product of the gas concentration change index of the sulfur hexafluoride ring main unit at the current moment and the gas pressure change law index.

9. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 6, characterized in that: The expression of the corrected standard fraction of the gas concentration at the current moment is: ; In the formula, Indicates the corrected standard score at the current moment; Indicates the standard fraction of gas concentration at the current moment; Indicates the gas concentration change factor of the sulfur hexafluoride ring main unit at the current moment.

10. The gas leakage detection method for sulfur hexafluoride ring main unit according to claim 1, characterized in that: The gas leakage detection of the sulfur hexafluoride ring main unit includes: If the corrected standard score of the gas concentration at the current moment is greater than the preset threshold, then gas leakage occurs in the sulfur hexafluoride ring main unit; otherwise, there is no gas leakage in the sulfur hexafluoride ring main unit.

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