Current transformer defect judgment method and system based on internal pressure change

Abstract

The invention discloses a current transformer defect judgment method and system based on internal pressure change. The method comprises the following steps: acquiring internal pressure monitoring data of a current transformer; based on a vertical and horizontal data comparison method, judging whether the change rates of adjacent monitoring data in a data interval first duration are consistent or not, and obtaining a first judgment result; if the first judgment result is consistent, continuing to judge whether the difference value of every two-phase data of the three-phase equipment is fixed or not, and if the difference value of every two-phase data of the three-phase equipment is fixed, determining that the equipment is in a normal state; if the first judgment result is inconsistent, continuing to judge whether the adjacent monitoring data variation in the data adjacent interval second duration is consistent or not, and obtaining a second judgment result; and judging a slow gas production defect and a rapid gas production defect according to the second judgment result and the change of the growth rate of the internal pressure of the oil-immersed inverted current transformer. According to the invention, the problems of poor timeliness of off-line detection, poor accuracy of on-line monitoring and incapability of judging slow gas production defect and rapid gas production defect in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power testing, and in particular to a method and system for judging defects of a current transformer based on internal pressure changes. Background Art

[0002] As an indispensable electrical device in the power system, the main function of the current transformer is to convert high current into low current for the purpose of measuring and protecting the circuit. Due to its special synergy, the current transformer is widely distributed in the equipment site and may be directly connected to transformers, busbars, circuit breakers and other equipment. Therefore, the safe and stable operation of the current transformer plays a vital role in the stable operation of the power system. In recent years, power outages caused by current transformer failures have occurred frequently. How to quickly and accurately detect and prevent the occurrence of faults in the early stage of the development of current transformer defects is of great significance to the safe and stable operation of the power grid.

[0003] As a fully sealed device, the current transformer has a metal expander installed on the top of the oil storage cabinet. Under normal operating conditions, the volume change of the insulating oil caused by the temperature is compensated by the expansion and contraction of the metal expander. However, when the current transformer has an electric heating fault, the insulating oil decomposes to produce a large amount of gas. If the gas generation speed is slow, these gases can slowly escape into the expander, causing the expander to stretch; if the gas generation speed is fast, the gas does not have time to escape upward into the expander, and the huge pressure generated by the gas can easily cause the current transformer to explode. For the early detection of current transformer defects, many monitoring methods are currently widely studied, including offline detection methods - analysis of dissolved gas in oil, measurement of capacitance and dielectric loss factor, partial discharge measurement, etc., and online monitoring methods - infrared temperature measurement, ultra-high frequency monitoring, ultrasonic partial discharge monitoring and oil pressure online monitoring. However, the current offline detection method has poor timeliness due to the need for power outage; and the online monitoring methods such as infrared temperature measurement are easily affected by environmental factors and have poor accuracy. Therefore, the oil pressure online monitoring technology has attracted more and more attention because it monitors physical quantities and is not easily affected by electromagnetic interference. However, there is little research on how to accurately judge the operating status of the current transformer based on the changes in oil pressure monitoring data.

[0004] In summary, in the process of implementing the technical solution of the present invention, the inventors of the present application found that the above technology has at least the following technical problems:

[0005] In the existing technology, the offline detection methods such as dissolved gas analysis in oil are used to monitor the operating status of the current transformer, but the timeliness is poor. When online monitoring methods such as infrared temperature measurement are used, they are easily affected by environmental factors and have poor accuracy. There is little research on the more useful online oil pressure monitoring technology, which uses its monitoring data to accurately judge the operating status of the current transformer. Summary of the invention

[0006] The purpose of the present invention is to provide a current transformer defect judgment method and system based on internal pressure changes. Based on the longitudinal data comparison method and the transverse data comparison method, the normal gas production, slow gas production defects and rapid gas production defects caused by the decomposition of the insulating oil inside the oil-immersed inverted current transformer are judged, which solves the existing problems of poor timeliness of offline detection, poor accuracy of online monitoring, and inability to judge defects such as slow gas production defects and rapid gas production. Through this judgment method, the electric and thermal defects of the current transformer can be effectively captured at an early stage to avoid the further development of the defects leading to the occurrence of serious accidents such as explosions.

[0007] The present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for judging a defect of a current transformer based on internal pressure change, the method comprising:

[0009] Obtain internal pressure monitoring data of oil-immersed inverted current transformer;

[0010] According to the internal pressure monitoring data, based on the vertical and horizontal data comparison method, it is judged whether the change rates of adjacent monitoring data within the first time interval of the data are consistent, and a first judgment result is obtained;

[0011] If the first judgment result is consistent, then continue to judge whether the data difference between each two phases of the three-phase device is constant. If the data difference between each two phases of the three-phase device is constant, the device is in a normal state;

[0012] If the first judgment result is inconsistent, continue to judge whether the changes in the adjacent monitoring data within the second time interval of the adjacent data are consistent, and obtain a second judgment result;

[0013] According to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer, the slow gas generation defect and the fast gas generation defect are continued to be judged.

[0014] Furthermore, the oil-immersed inverted current transformer is a fully sealed assembly, the capacitive main insulation package is on the secondary winding shielding cover and secondary lead tube which are at ground potential in normal operation, the outermost electric screen is connected to high voltage, and the innermost electric screen is grounded; a metal expander is provided at the upper end of the oil storage cabinet to compensate for the change in oil volume, which can also serve as a pressure relief device in the event of a fault.

[0015] Furthermore, the first judgment result is consistent, including:

[0016] When the ambient temperature and equipment load are consistent, the internal oil temperature of the insulating oil of the oil-immersed inverted current transformer is consistent, and the force exerted by the insulating oil on the metal expander is consistent.

[0017] Furthermore, the first duration is 24 hours, and the second duration is 10 minutes.

[0018] Furthermore, the data difference between each two phases of the three-phase device is certain, including:

[0019] The difference between the pressure of the a-phase device and the pressure of the b-phase device is equal to the difference between the pressure of the a-phase device before the first time length and the pressure of the b-phase device before the first time length;

[0020] The difference between the pressure of the a-phase device and the pressure of the c-phase device is equal to the difference between the pressure of the a-phase device before the first time length and the pressure of the c-phase device before the first time length;

[0021] The difference between the pressure of the b-phase device and the pressure of the c-phase device is greater than the difference between the pressure of the b-phase device before the first time length and the pressure of the c-phase device before the first time length.

[0022] Furthermore, the slow gas generation defect refers to the linear change of the pressure growth inside the oil-immersed inverted current transformer, which comes from the elastic force caused by the stretching of the metal expander caused by the gas generated by the decomposition of the insulating oil diffusing into the metal expander;

[0023] Rapid gas generation defect refers to the exponential increase in pressure inside the oil-immersed inverted current transformer, which comes from the gas interaction force generated by the decomposition of insulating oil.

[0024] Further, according to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer, the slow gas generation defect and the fast gas generation defect are further judged, including:

[0025] If the second judgment result is consistent, then continue to judge whether the difference between the data of each two phases of the three-phase device is constant. If it is constant, the device is in a normal state; if it is not constant, then continue to judge whether the difference between the data of one phase of the three-phase device and the data of the other two phases is constantly increasing. If so, the phase device has a slow gas production defect;

[0026] If the second judgment result is inconsistent, and the growth rate of the internal pressure of the oil-immersed inverted current transformer continues to increase, then continue to judge whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases continues to increase. If so, the phase equipment has a rapid gas production defect.

[0027] Furthermore, it is determined that the difference between the data of one phase of the three-phase device and the data of the other two phases is increasing, including:

[0028] The difference between the pressure of the phase a device and the pressure of the phase b device is greater than the difference between the pressure of the phase a device before the first time length and the pressure of the phase b device before the first time length;

[0029] The difference between the pressure of the a-phase device and the pressure of the c-phase device is greater than the difference between the pressure of the a-phase device before the first time length and the pressure of the c-phase device before the first time length;

[0030] The difference between the pressure of the phase b device and the pressure of the phase c device is greater than the difference between the pressure of the phase b device before the first time length and the pressure of the phase c device before the first time length.

[0031] In a second aspect, the present invention further provides a current transformer defect judgment system based on internal pressure change, the system comprising:

[0032] An acquisition unit, used for acquiring internal pressure monitoring data of the oil-immersed inverted current transformer;

[0033] A first judgment unit is used to judge whether the change rates of adjacent monitoring data within a first time interval of the data are consistent based on the vertical and horizontal data comparison method according to the internal pressure monitoring data, and obtain a first judgment result;

[0034] A second judgment unit is used for continuing to judge whether the data difference between each two phases of the three-phase device is constant if the first judgment result is consistent, and if the data difference between each two phases of the three-phase device is constant, the device is in a normal state;

[0035] A third judgment unit is used to, if the first judgment result is inconsistent, continue to judge whether the changes in the adjacent monitoring data within the second time length of the adjacent interval of the data are consistent, to obtain a second judgment result;

[0036] a fourth judgment unit, configured to continue judging the slow gas generation defect and the fast gas generation defect according to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer;

[0037] The judgment process of the fourth judgment unit includes:

[0038] If the second judgment result is consistent, then continue to judge whether the difference between the data of each two phases of the three-phase device is constant. If it is constant, the device is in a normal state; if it is not constant, then continue to judge whether the difference between the data of one phase of the three-phase device and the data of the other two phases is constantly increasing. If so, the phase device has a slow gas production defect;

[0039] If the second judgment result is inconsistent, and the growth rate of the internal pressure of the oil-immersed inverted current transformer continues to increase, then continue to judge whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases continues to increase. If so, the phase equipment has a rapid gas production defect.

[0040] In a third aspect, the present invention further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned current transformer defect judgment method based on internal pressure changes is implemented.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] 1. The present invention provides a current transformer defect judgment method and system based on internal pressure changes. Based on the longitudinal data comparison method and the transverse data comparison method, the normal gas production, slow gas production defects and rapid gas production defects caused by the decomposition of the insulating oil inside the oil-immersed inverted current transformer are judged, which solves the existing problems of poor timeliness of offline detection, poor accuracy of online monitoring, and inability to judge defects such as slow gas production defects and rapid gas production. Through this judgment method, the electric and thermal defects of the current transformer can be effectively captured at an early stage to avoid the further development of the defects leading to the occurrence of serious accidents such as explosions.

[0043] 2. The present invention is based on the current transformer defect judgment method and system based on the internal pressure change. The slow gas generation defect refers to the pressure growth inside the oil-immersed inverted current transformer showing a linear change, which comes from the elastic force caused by the metal expander stretching caused by the gas generated by the decomposition of the insulating oil diffusing into the metal expander; the rapid gas generation defect refers to the pressure growth inside the oil-immersed inverted current transformer showing an exponential change, which comes from the gas interaction force generated by the decomposition of the insulating oil. By using this defect judgment method, defects in the current transformer can be discovered in time, avoiding the shortcomings of low efficiency and low effectiveness of manual inspections, and avoiding the further development of defects and even the occurrence of failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0045] Figure 1 Schematic diagram of gas production inside the oil-immersed inverted current transformer of the present invention (a) normal working state of the current transformer, (b) slow gas production state inside the current transformer, (c) normal working state of the current transformer, (d) rapid gas production state inside the current transformer;

[0046] Figure 2 It is the pressure monitoring value of the A, B, and C phases of the busbar switch current transformer of a 220kV substation of the present invention under normal operating conditions;

[0047] Figure 3 This is a three-phase pressure monitoring spectrum of a 500kV current transformer of the present invention (a phase has a slowly developing defect);

[0048] Figure 4 This is a graph showing the change of the three-phase pressure difference of a 500kV current transformer of the present invention (a phase has a slow development defect);

[0049] Figure 5 It is a pressure monitoring spectrum of a fault phase and a normal phase of a 500kV current transformer of a 500kV substation of the present invention;

[0050] Figure 6 This is a flow chart of a method for judging a defect of a current transformer based on internal pressure change according to the present invention;

[0051] Figure 7 It is a detailed flow chart of the current transformer defect judgment method based on internal pressure change of the present invention;

[0052] Figure 8 This is a structural block diagram of the current transformer defect judgment system based on internal pressure changes of the present invention. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0054] In order to solve the existing problems of poor timeliness of offline detection, poor accuracy of online monitoring, and inability to judge defects such as slow gas production defects and rapid gas production defects, the present invention designs a current transformer defect judgment method and system based on internal pressure changes, which can effectively capture electric and thermal defects of current transformers at an early stage, and avoid the further development of defects leading to the occurrence of serious accidents such as explosions.

[0055] The design process of the present invention is as follows:

[0056] Under normal operating conditions, since the oil-immersed inverted current transformer is filled with insulating oil, when the temperature changes, the oil level changes due to the expansion of the insulating oil, and the metal expander adjusts by stretching and contracting. Therefore, the pressure inside the current transformer only changes slightly due to a small change in the oil level, and the overall change is not large. However, when an electric heating defect occurs inside the current transformer, the insulating oil inside the current transformer decomposes to produce a large amount of gas. According to the chemical structure of transformer oil, CH3-(CH2) n -CH3 and the law of conservation of mass show that when insulating oil decomposes to produce gas molecules such as CH4, C2H4, C2H6, C2H2 and H2, the total number of gas molecules will inevitably be greater than the number of molecules of the original insulating oil, and the distance between gas molecules is much larger than that of liquid molecules, which will lead to an increase in the internal pressure of the equipment. If the gas generation rate is slow, there is enough time to escape into the metal expander. After the metal expander is continuously stretched to the maximum extent under pressure, the sealing is eventually destroyed under the continuous action of internal pressure. If the energy of the electrothermal fault inside the current transformer is high, resulting in the inability of the gas generated by decomposition in a short time to diffuse into the metal expander, due to the relatively limited volume of the current transformer, the continuous increase in pressure will cause the current transformer to explode and other serious accidents. At the same time, when the current transformer has an electrothermal fault, the local temperature will also increase. While generating gas, the temperature addition will cause the internal pressure of the equipment to further increase.

[0057] According to the structure of the oil-immersed inverted current transformer, it can be known that when an electric heating fault occurs in the current transformer, three forces will exist simultaneously inside, namely, the gas pressure caused by the gas generated by the decomposition of the insulating oil, the elastic force of the metal expander caused by the expansion of the gas and the insulating oil, and the pressure change caused by the volume expansion of the insulating oil as the temperature increases.

[0058] (1) Pressure changes caused by the volume expansion of insulating oil as temperature increases:

[0059] According to the definition of volume expansion:

[0060] V2=V1[1+γ(T2-T1)]

[0061] Where γ is the volume expansion coefficient, V1 and V2 are the volumes of a substance at temperatures T1 and T2 respectively.

[0062] When the temperature rises from T1 to T2, the change in volume is:

[0063] ΔV=V2-V1=(T2-T1)γV1

[0064] Table 1 Expansion coefficient of various materials of current transformer

[0065] Insulating oil (1 / K) Carbon fiber (1 / K) Aluminum foil (1 / K) Linear expansion coefficient / <![CDATA[-0.5*10 -6 ]]> <![CDATA[23.3*10 -6 ]]> Coefficient of surface expansion / <![CDATA[-1*10 -6 ]]> <![CDATA[46.6*10 -6 ]]> Volume expansion coefficient 0.0008 <![CDATA[-1.5*10 -6 ]]> <![CDATA[69.9*10 -6 ]]>

[0066] The expansion coefficients of the materials that make up the current transformer are detailed in Table 1. From the data in Table 1, it can be seen that the volume expansion coefficient of the insulating oil is more than 100 times that of other substances. Therefore, the volume change of the insulating material inside the current transformer with temperature changes can be ignored. The pressure of the insulating oil on the bottom of the current transformer is

[0067]

[0068] The total mass of the insulating oil in the current transformer remains unchanged. According to the expansion coefficients of the materials in Table 1, the effect of temperature changes on the bottom area of ​​the current transformer can be ignored, so

[0069]

[0070] It can be seen that the volume change of the insulating oil caused by the temperature change will not cause a large change in the pressure at the bottom of the current transformer. However, after the insulating oil expands due to heat, it will cause the elastic deformation of the metal expander, causing the metal expander to produce a certain elastic force.

[0071] According to Hooke's law, F = kx, where F is the elastic force, k is the elastic coefficient of the metal expander, and x is the volume change of the metal expander. K is a constant, and the change of the elastic force is only related to the stretching degree of the metal expander.

[0072] (2) Gas pressure caused by the decomposition of insulating oil

[0073] According to the ideal gas law, PV=nRT, where P is the pressure of the gas, V is the volume of the gas, n is the amount of substance in the gas, R is a constant, and T is the temperature.

[0074] For the defect of slow gas production, as the gas is produced, the gas slowly escapes into the expander, the temperature change is negligible, the amount of gas n and the volume V of the gas increase at the same time, part of the gas dissolves into the insulating oil, and part of the gas diffuses into the metal expander, so the gas pressure shows a slight increase, and as the gas is continuously produced, the gas pressure continues to increase.

[0075] As for the defect of rapid gas production, since the generated gas does not have time to diffuse into the metal expander, the amount of gas increases greatly in a short time, and does not show obvious volume change when dissolved in the insulating oil, resulting in a sharp increase in the internal pressure of the current transformer.

[0076] (3) Elastic force of the metal expander caused by the expansion of gas and insulating oil

[0077] According to Hooke's law, F=kx, where F is the elastic force, k is the elastic coefficient of the metal expander, and x is the volume change of the metal expander.

[0078] As for the defect of slow gas generation, the gas slowly diffuses into the metal expander, causing the volume of the metal expander to increase, thereby causing the metal expander to generate a larger elastic force.

[0079] As for the defect of rapid gas production, since the gas does not have time to diffuse into the metal expander, the volume of the metal expander does not change significantly, so the metal expander does not generate obvious elastic force.

[0080] In summary, the study found that for defects with slow gas generation, the pressure change inside the current transformer is mainly due to the elastic force caused by the metal expander stretching caused by the gas generated by the decomposition of the insulating oil diffusing into the metal expander; for defects with rapid gas generation, the pressure change inside the current transformer is mainly due to the gas interaction force generated by the decomposition of the insulating oil. Figure 1 As shown in (a) to (d).

[0081] In actual production, the oil temperature will change with the outdoor temperature and current, causing its pressure to be a dynamic value. Taking 24 hours as a cycle, the ambient temperature and current in the same period of adjacent cycles will not change significantly, that is, the oil temperature in the same period of adjacent cycles is similar. Therefore, for the same current transformer, under normal operation, its oil temperature shows a periodic change law, so that the elastic force of the metal expander changes with the change of the insulating oil volume, so its internal pressure should show a periodic change, such as Figure 2 As shown in the figure, the pressure monitoring of the A, B, and C phases of the busbar switch current transformer of a 220kV substation under normal operating conditions. Figure 2 The horizontal axis represents time, and the vertical axis represents pressure (kPa).

[0082] Therefore, under the same operating environment, that is, when the ambient temperature and current are the same, if the pressure inside the current transformer changes significantly, it can be determined that there is a defect inside the current transformer. Because the development speed of the defect is different, the pressure performance of the current transformer presents different types of changes, as follows:

[0083] 1. For slowly developing defects, the gas generated by them slowly diffuses into the metal expander, and the increase in pressure is mainly due to the elastic force of the metal expander, showing a linear growth relationship. Using the longitudinal comparison method, it is shown that for a single-phase device with defects, under the same operating conditions as other cycles, the pressure inside the equipment increases compared to before, and as the operating cycle continues, the pressure monitoring value continues to increase. Using the horizontal comparison method, for the pressure difference between phases, it is intuitively shown that the absolute value of the pressure difference between the defective phase and the other two normal phases continues to increase. Figure 3 and Figure 4 As shown, Figure 3 and Figure 4 The horizontal axis represents time, and the vertical axis represents pressure (kPa).

[0084] 2. For rapidly developing defects, the gas generated by them has no time to diffuse, and a large amount of gas accumulates in the body of the current transformer. The pressure inside the equipment is mainly the gas interaction force generated by the decomposition of the insulating oil, showing an exponential growth characteristic. Using the longitudinal comparison method, it is manifested that for single-phase equipment with defects, the pressure inside the equipment increases sharply in a short period of time, and the periodic law of pressure change inside the equipment is destroyed. Using the horizontal comparison method, the pressure difference between the phases is intuitively manifested as the absolute value of the pressure difference between the defective phase and the other two normal phases continues to increase. In addition, in the monitoring value of the internal pressure of the equipment, the pressure growth rate also shows an increasing trend, and the pressure growth rate can increase to 100% or even more than 200%. If Figure 5 As shown, Figure 5 The horizontal axis represents time and the vertical axis represents pressure (mbar).

[0085] The present invention obtains a method for judging defects in a power transformer by monitoring the changes in the internal pressure of the current transformer under different defect types, which is specifically as follows:

[0086] (1) Under normal operating conditions, the pressure inside the current transformer changes periodically with the change of oil temperature. Due to the expansion compensation of the expander, the difference between the highest pressure and the lowest pressure in the current transformer is generally about several kilopascals.

[0087] (2) When a slowly developing defect occurs in the current transformer, the increase in pressure in the current transformer is mainly due to the elastic force of the metal expander, showing a linear growth relationship, and the pressure still shows a periodic change law. However, the pressure value in the equipment in the latter cycle is higher than that in the previous cycle under the same operating conditions in different cycles, and the absolute value of the pressure difference between the defective phase and the other two normal phases continues to increase.

[0088] (3) When a rapidly developing defect occurs in the current transformer, the pressure inside the current transformer is mainly the gas interaction force generated by the decomposition of the insulating oil, showing an exponential growth characteristic. The periodic change law of the pressure in the equipment is destroyed. Calculated with a sampling period of 10 minutes, the growth rate of pressure continues to increase and can exceed 100%, and the absolute value of the pressure difference between the defective phase and the other two normal phases continues to increase.

[0089] By adopting this defect judgment method, defects in the current transformer can be discovered in time, avoiding the shortcomings of low efficiency and low effectiveness of manual inspection, and preventing the further development of defects or even the occurrence of failures.

[0090] Example 1

[0091] like Figure 6 and Figure 7 As shown, the present invention provides a method for judging defects of a current transformer based on internal pressure changes, the method comprising:

[0092] Step 1, obtaining internal pressure monitoring data of the oil-immersed inverted current transformer;

[0093] In this embodiment, the oil-immersed inverted current transformer is a fully sealed assembly. The capacitive main insulation package is on the secondary winding shielding cover and secondary lead tube which are at ground potential in normal operation. The outermost electric screen is connected to high voltage and the innermost electric screen is grounded. A metal expander is provided at the upper end of the oil storage cabinet to compensate for the change in oil volume, which can also serve as a pressure relief device in the event of a fault.

[0094] Step 2, based on the internal pressure monitoring data, based on the vertical and horizontal data comparison method, determine whether the change rates of adjacent monitoring data within a first data interval (for example, 24 hours) are consistent, and obtain a first judgment result, including:

[0095] When the ambient temperature and equipment load are consistent, the internal oil temperature of the insulating oil of the oil-immersed inverted current transformer is consistent, and the force exerted by the insulating oil on the metal expander is consistent, then the change rates of adjacent monitoring data within the first time period of the data interval (for example, 24 hours) are consistent, otherwise they are inconsistent.

[0096] Step 3, if the first judgment result is consistent, then use the longitudinal data comparison method to continue to determine whether the difference between the data of each two phases of the three-phase device is constant. If the difference between the data of each two phases of the three-phase device is constant, the device is in a normal state;

[0097] In this embodiment, the data difference between every two phases of the three-phase device is certain, including:

[0098] a-phase equipment pressure P a and b-phase equipment pressure P b The difference is equal to the pressure P of the a-phase equipment 24 hours ago a(24h前) The pressure P of the b-phase equipment 24 hours ago b(24h前) The difference, that is, P a -P b =P a(24h前) -P b(24h前) ;

[0099] a-phase equipment pressure P a and the c-phase equipment pressure P c The difference is equal to the pressure P of the a-phase equipment 24 hours ago a(24h前) The pressure P of the c-phase equipment 24 hours ago c(24h前) The difference, that is, P a -P c =P a(24h前) -P c(24h前) ;

[0100] b-phase equipment pressure P b and the c-phase equipment pressure P c The difference is greater than the pressure P of the b-phase equipment 24 hours ago b(24h前) The pressure P of the c-phase equipment 24 hours ago c(24h前) The difference, that is, P b -P c =P b(24h前) -P c(24h前) .

[0101] Step 4: If the first judgment result is inconsistent, continue to judge whether the change rates of adjacent monitoring data within a second time interval (for example, 10 minutes) are consistent to obtain a second judgment result;

[0102] Determine whether the changes in adjacent monitoring data within 10 minutes of each other are consistent. The judgment formula is:

[0103] If they are consistent, then it means they are consistent, otherwise they are inconsistent.

[0104] Step 5: Continue to judge the slow gas generation defect and the fast gas generation defect according to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer.

[0105] In this embodiment, the slow gas generation defect refers to the linear change of the pressure growth inside the oil-immersed inverted current transformer, which is derived from the elastic force caused by the stretching of the metal expander caused by the gas generated by the decomposition of the insulating oil diffusing into the metal expander;

[0106] Rapid gas generation defect refers to the exponential increase in pressure inside the oil-immersed inverted current transformer, which comes from the gas interaction force generated by the decomposition of insulating oil.

[0107] In this embodiment, step 5 specifically includes:

[0108] Step 51, if the second judgment result is consistent, continue to judge whether the difference between the data of each two phases of the three-phase device is constant, and the judgment method is similar to step 3;

[0109] If it is certain, the device is in normal state;

[0110] If not necessarily, continue to determine whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases is increasing. If so, the a-phase equipment has a slow gas production defect;

[0111] Step 52: If the second judgment result is inconsistent, and the growth rate of the internal pressure of the oil-immersed inverted current transformer continues to increase Then continue to judge whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases is constantly increasing. If so, the a-phase equipment has a rapid gas production defect.

[0112] In step 52, it is determined that the difference between the data of one phase of the three-phase device and the data of the other two phases is increasing, specifically including:

[0113] (1) Phase a equipment pressure P a and b-phase equipment pressure P b The difference is greater than the pressure P of the a-phase equipment 24 hours ago. a(24h前) The pressure P of the b-phase equipment 24 hours ago b(24h前) The difference, that is, P a -P b >P a(24h前) -P b(24h前) ;

[0114] (2) Phase a equipment pressure P a and the c-phase equipment pressure P c The difference is greater than the pressure P of the a-phase equipment 24 hours ago. a(24h前) The pressure P of the c-phase equipment 24 hours agoc(24h前) The difference, that is, P a -P c >P a(24h前) -P c(24h前) ;

[0115] (3) Equipment pressure of phase b and equipment pressure of phase c P c The difference is greater than the pressure P of the b-phase equipment 24 hours ago. b(24h前) The pressure P of the c-phase equipment 24 hours ago c(24h前) The difference, that is, P b -P c >P b(24h前) -P c(24前) .

[0116] According to the above steps, it is possible to quickly determine whether the equipment is in a normal state, whether the phase A equipment has a slow gas production defect, or whether the phase A equipment has a fast gas production defect. The determination of phases B and C can be carried out according to the phase A process.

[0117] Therefore, the present invention judges the normal gas production, slow gas production defects and rapid gas production defects caused by the decomposition of the insulating oil inside the oil-immersed inverted current transformer based on the longitudinal data comparison method and the transverse data comparison method, thereby solving the existing problems of poor timeliness of offline detection, poor accuracy of online monitoring, and inability to judge defects such as slow gas production defects and rapid gas production. Through this judgment method, the electric and thermal defects of the current transformer can be effectively captured at an early stage, thereby avoiding the further development of the defects and the occurrence of serious accidents such as explosions.

[0118] Example 2

[0119] like Figure 8 As shown, the difference between this embodiment and embodiment 1 is that this embodiment provides a current transformer defect judgment system based on internal pressure change, and the system corresponds to the current transformer defect judgment method based on internal pressure change in embodiment 1 in a one-to-one manner; the system includes:

[0120] An acquisition unit, used for acquiring internal pressure monitoring data of the oil-immersed inverted current transformer;

[0121] A first judgment unit is used to judge whether the change rates of adjacent monitoring data within a first time interval of the data are consistent based on the vertical and horizontal data comparison method according to the internal pressure monitoring data, and obtain a first judgment result;

[0122] A second judgment unit is used for continuing to judge whether the data difference between each two phases of the three-phase device is constant if the first judgment result is consistent, and if the data difference between each two phases of the three-phase device is constant, the device is in a normal state;

[0123] A third judgment unit is used to, if the first judgment result is inconsistent, continue to judge whether the changes in the adjacent monitoring data within the second time length of the adjacent interval of the data are consistent, to obtain a second judgment result;

[0124] a fourth judgment unit, configured to continue judging the slow gas generation defect and the fast gas generation defect according to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer;

[0125] The judgment process of the fourth judgment unit includes:

[0126] If the second judgment result is consistent, continue to judge whether the difference between the data of each two phases of the three-phase device is constant. If it is constant, the device is in a normal state; if it is not constant, continue to judge whether the difference between the data of one phase of the three-phase device and the other two phases is not

[0127] If the value is not stable, the equipment has a slow gas production defect.

[0128] If the second judgment result is inconsistent, and the growth rate of the internal pressure of the oil-immersed inverted current transformer continues to increase, then continue to judge whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases continues to increase. If so, the phase equipment has a rapid gas production defect.

[0129] Among them, the execution process of each unit can be executed according to the process steps of the current transformer defect judgment method based on internal pressure change in Example 1, and will not be repeated one by one in this embodiment.

[0130] At the same time, the present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned current transformer defect judgment method based on internal pressure change is implemented.

[0131] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0132] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0133] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0134] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0135] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for judging defects of a current transformer based on internal pressure changes, characterized in that: The method includes: Obtain internal pressure monitoring data of oil-immersed inverted current transformer; According to the internal pressure monitoring data, based on the vertical and horizontal data comparison method, determine whether the change rates of adjacent monitoring data within a first data interval are consistent, and obtain a first judgment result; If the first judgment result is consistent, continue to judge whether the data difference between each two phases of the three-phase device is constant. If the data difference between each two phases of the three-phase device is constant, the device is in a normal state; If the first judgment result is inconsistent, continue to judge whether the changes in the adjacent monitoring data within the second time length of the adjacent interval of the data are consistent, and obtain a second judgment result; According to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer, the slow gas generation defect and the fast gas generation defect are further judged.

2. The method for judging defects of a current transformer based on internal pressure changes according to claim 1, characterized in that: The oil-immersed inverted current transformer is a fully sealed assembly, with the capacitive main insulation package being on the secondary winding shielding cover and secondary lead tube which are at ground potential in normal operation, the outermost electric screen being connected to high voltage, and the innermost electric screen being grounded; a metal expander is provided at the upper end of the oil storage cabinet to compensate for changes in oil volume, and also serves as a pressure release device in the event of a fault.

3. The method for judging defects of a current transformer based on internal pressure changes according to claim 1, characterized in that: The first judgment result is consistent, including: When the ambient temperature and equipment load are consistent, the internal oil temperature of the insulating oil of the oil-immersed inverted current transformer is consistent, and the force exerted by the insulating oil on the metal expander is consistent.

4. The method for judging defects of a current transformer based on internal pressure changes according to claim 1, characterized in that: The first duration is 24 hours, and the second duration is 10 minutes.

5. The method for judging defects of a current transformer based on internal pressure changes according to claim 1, characterized in that: The data difference between each two phases of three-phase equipment is certain, including: The difference between the pressure of the a-phase device and the pressure of the b-phase device is equal to the difference between the pressure of the a-phase device before the first time length and the pressure of the b-phase device before the first time length; The difference between the pressure of the a-phase device and the pressure of the c-phase device is equal to the difference between the pressure of the a-phase device before the first time length and the pressure of the c-phase device before the first time length; The difference between the pressure of the b-phase device and the pressure of the c-phase device is greater than the difference between the pressure of the b-phase device before the first time length and the pressure of the c-phase device before the first time length.

6. The method for judging defects of a current transformer based on internal pressure changes according to claim 1, characterized in that: The slow gas generation defect refers to the linear change of the pressure growth inside the oil-immersed inverted current transformer, which is caused by the elastic force of the metal expander stretched due to the diffusion of the gas generated by the decomposition of the insulating oil into the metal expander; The rapid gas generation defect refers to the exponential increase in pressure inside the oil-immersed inverted current transformer, which is derived from the gas interaction force generated by the decomposition of the insulating oil.

7. The method for judging defects of a current transformer based on internal pressure changes according to claim 1, characterized in that: According to the second judgment result and the change in the growth rate of the internal pressure of the oil-immersed inverted current transformer, the slow gas generation defect and the fast gas generation defect are further judged, including: If the second judgment result is consistent, then continue to judge whether the difference between the data of each two phases of the three-phase device is constant. If it is constant, the device is in a normal state; if it is not constant, then continue to judge whether the difference between the data of one phase of the three-phase device and the data of the other two phases is constantly increasing. If so, the phase device has a slow gas production defect; If the second judgment result is inconsistent and the growth rate of the internal pressure of the oil-immersed inverted current transformer continues to increase, continue to judge whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases continues to increase. If so, the phase equipment has a rapid gas production defect.

8. The method for judging defects of a current transformer based on internal pressure changes according to claim 7, characterized in that: Determine whether the difference between one phase of a three-phase device and the other two phases is increasing, including: The difference between the pressure of the phase a device and the pressure of the phase b device is greater than the difference between the pressure of the phase a device before the first time length and the pressure of the phase b device before the first time length; The difference between the pressure of the a-phase device and the pressure of the c-phase device is greater than the difference between the pressure of the a-phase device before the first time length and the pressure of the c-phase device before the first time length; The difference between the pressure of the b-phase device and the pressure of the c-phase device is greater than the difference between the pressure of the b-phase device before the first time period and the pressure of the c-phase device before the first time period.

9. A current transformer defect judgment system based on internal pressure change, characterized in that: The system includes: An acquisition unit, used for acquiring internal pressure monitoring data of the oil-immersed inverted current transformer; A first judgment unit is used to judge whether the change rates of adjacent monitoring data within a first time interval of the data are consistent based on the vertical and horizontal data comparison method according to the internal pressure monitoring data, and obtain a first judgment result; A second judgment unit is used for continuing to judge whether the data difference between each two phases of the three-phase device is constant if the first judgment result is consistent, and if the data difference between each two phases of the three-phase device is constant, the device is in a normal state; A third judgment unit is used to, if the first judgment result is inconsistent, continue to judge whether the changes in the adjacent monitoring data within the second time length of the adjacent interval of the data are consistent, to obtain a second judgment result; a fourth judgment unit, configured to continue judging a slow gas generation defect and a fast gas generation defect according to the second judgment result and a change in the growth rate of the internal pressure of the oil-immersed inverted current transformer; The judgment process of the fourth judgment unit includes: If the second judgment result is consistent, then continue to judge whether the difference between the data of each two phases of the three-phase device is constant. If it is constant, the device is in a normal state; if it is not constant, then continue to judge whether the difference between the data of one phase of the three-phase device and the data of the other two phases is constantly increasing. If so, the phase device has a slow gas production defect; If the second judgment result is inconsistent and the growth rate of the internal pressure of the oil-immersed inverted current transformer continues to increase, continue to judge whether the difference between the data of one phase of the three-phase equipment and the data of the other two phases continues to increase. If so, the phase equipment has a rapid gas production defect.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for judging defects of a current transformer based on internal pressure changes as described in any one of claims 1 to 8 is implemented.

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