Continuous monitoring of moisture content in solid transformer insulation

Abstract

A system, method, and / or computer program for measuring moisture content in insulating material of a transformer includes obtaining temperature and relative humidity measurements at two points in the oil, where the two temperatures are different; obtaining a temperature measurement in the insulating material; obtaining material-specific parameters (a, b, k, and d) for the insulating material; and calculating the moisture content in the insulating material from the relative humidity and temperature at the two points in the oil using the insulating material parameters and according to the temperature measured in the insulating material.

Description

[Technical Field]

[0001] The methods and apparatus disclosed herein relate to the field of electrical grids, and more particularly, but not exclusively, to transformers and reactors in electrical utilities, power plants and substations, and more particularly, but not exclusively, to monitoring and calculating moisture content in solid insulation in transformers. [Background technology]

[0002] Transformers are a key component of every electrical utility and grid. They are immersed in a dielectric fluid and consist of a magnetic core and windings. The windings contain conductor wires insulated with cellulose paper, e.g., kraft paper. Insulation between the windings, between the windings and the core, and between the windings and the tank containing the dielectric fluid is provided by pressboard.

[0003] Moisture in insulating materials adversely affects their properties. In transformers, approximately 99% of the moisture is in the cellulose insulation and 1% in the oil. An increase in the amount of moisture in the insulation can lead to the formation of partial discharges and electrical breakdowns.

[0004] The lack of direct access to the measurement of the moisture content of the solid insulation leads to an indirect assessment through the measurement of the moisture content of the insulating liquid. Since the moisture absorption parameters of insulating liquids are different, for the same liquid, these parameters may change during the operation of the transformer.

[0005] Therefore, it would be highly advantageous to have a method and system for continuously measuring the water content of oil in insulating materials. Summary of the Invention [Means for solving the problem]

[0006] According to one exemplary embodiment, a system, method, and / or computer program is provided for measuring moisture content in insulating material of a transformer, comprising obtaining temperature and relative humidity measurements at two points in the oil, the two temperatures being different; obtaining a temperature measurement in the insulating material; obtaining material-specific parameters (a, b, k, and d) for the insulating material; and calculating the moisture content in the insulating material from the relative humidity and temperature at the two points in the oil using the insulating material parameters and according to the temperature measured in the insulating material.

[0007] According to another exemplary embodiment, a fiber optic temperature sensor may be used to measure the temperature in the insulating material.

[0008] According to yet another exemplary embodiment, the obtained parameters are at least one of a=6.1, b=0.04, k=0.33, and d=0.0033 for Kraft paper and a=3.74, b=0.032, k=0.63, and d=-0.0017 for Pressboard B.

[0009] According to yet another exemplary embodiment, all measurements and calculations of the moisture content in the insulating material are performed repeatedly and / or continuously.

[0010] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the relevant art.The materials, methods, and examples provided herein are merely illustrative and are not intended to be limiting.Except to the extent necessary or essential in the process itself, no particular order of steps or stages of the methods and processes described in this disclosure, including the figures, is intended or implied.In many cases, the order of process steps can be varied without changing the purpose or effect of the method described. [Brief explanation of the drawings]

[0011] Various embodiments are herein described, by way of example only, with reference to the accompanying drawings. Referring now specifically to the drawings in detail, it is emphasized that the details shown are merely by way of example and for purposes of illustrative discussion of preferred embodiments, and are presented to provide what is believed to be the most useful and readily understood explanation of the principles and conceptual aspects of the embodiments.

[0012] In this regard, no attempt is made to show structural details of the embodiments in more detail than necessary for a fundamental understanding of the subject matter, and the description taken in conjunction with the drawings will make apparent to those skilled in the art how some forms and structures may be embodied in practice.

[0013] The drawings are as follows:

[0014] [Figure 1] FIG. 1 is a simplified diagram of a transformer monitoring system including a power transformer, a monitoring computer, and a sensor.

[0015] [Figure 2] FIG. 2 is a simplified block diagram of a computing device for monitoring a transformer system.

[0016] [Figure 3] FIG. 3 is a simplified flowchart of a process for calculating moisture content in the insulating material of a transformer. DETAILED DESCRIPTION OF THE INVENTION

[0017] Description of the embodiment The present embodiments comprise a system, method, and / or computer program for measuring the moisture content of insulating materials in transformers of an electrical grid.

[0018] The principles and operation of systems, methods, and / or computer programs for accurately determining the location of sources of electrical signals resulting from intermittent faults in electrical cables of an electrical grid, according to some example embodiments, may be better understood with reference to the following drawings and accompanying description.

[0019] Before describing at least one embodiment in detail, it is to be understood that the embodiments are not limited in their application to the details of the organization and arrangement of components set forth in the following description or illustrated in the drawings. Other embodiments may be practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0020] Elements of the drawings labeled with numbers not described within the drawings but described in previous drawings have the same purpose and description as in the previous drawing. Similarly, elements identified in the text by numbers that do not appear in the drawing described by the text have the same purpose and description as in the previous drawing in which they are described.

[0021] The drawings in this document may not be intended to be to any scale: different figures may use different scales, and different scales may even be used within the same drawing, for example, different scales are used for different views of the same object, or different scales are used for two adjacent objects.

[0022] The phrases "at least one," "one or more," and "and / or" are open-ended expressions that are both conjunctions and disjunctions in operation. For example, the expressions "at least one of A, B and C," "at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C," and "A, B, and / or C" each mean "A only," "B only," "C only," "A and B together," "A and C together," "B and C together," or "A, B, and C together." The term "a" or "an entity" refers to one or more of that entity. As such, the terms "a" (or "an"), "one or more," and "at least one" can be used interchangeably herein.

[0023] It should also be noted that the terms "comprising," "including," "containing," "characterized by," and "having" are all inclusive, open-ended, do not exclude additional, unrecited elements or method steps, and can be used synonymously. In particular, these terms may imply the inclusion of a stated integer or step or group of integers or steps, but may not imply the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising," such as "comprise" and "comprises."

[0024] References throughout this specification to "one embodiment," "an embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0025] As used herein, the term "plurality" is defined as two or more than two. As used herein, the term "another" is defined as at least a second or more. As used herein, the term "coupled" is defined as "connected," although not necessarily directly, and not necessarily mechanically.

[0026] As used herein, the term "computing device" may refer to any type of computing machine, including, but not limited to, a controller, a computer, a portable computer, a laptop computer, a tablet computer, a mobile communication device, a network server, a cloud computer, etc., and any combination thereof. Such a computing device or computing machine may include any type of device or combination thereof, including, but not limited to, a processor or processing device, a memory device, a storage device, a user interface device, and / or a communication device.

[0027] The terms "execute," "perform," "compute," "calculate," etc. may refer to a processor of a computing device executing software program code embodied on a non-transitory computer-readable medium to achieve a result as described after any of the terms "execute," "perform," "compute," "calculate," etc.

[0028] The terms "client computing device," or "client device," or "user device," may refer to any type of computing device that is used or operated directly by a user. Such a device may include a user interface that can be used directly by the user, including means for user input and / or user output. Such a device may be communicatively coupled to another computing device, such as a network server, via a communications network.

[0029] Means for user input may include a keyboard, a pointing device such as a mouse, a microphone, a camera, a touch-sensitive plate or display, means for user gesture control, means for tactile user control, and the like.

[0030] The means for user output may include a display and / or any other means for providing visual information, a speaker or earphones and / or any other means for providing audible information, means for providing tactile and / or tactile information, etc.

[0031] The term "communication network" or "network" may refer to any type or technology of digital communications, including, but not limited to, the Internet, WAN, LAN, MAN, PSDN, etc. Any of the above-mentioned technologies may be wired or wireless, e.g., wireless WANs such as WiMAX, WLAN (Wi-Fi), WPAN (Bluetooth®), etc. Wireless networking technologies may also include PLMNs and / or any type of cellular network. The term "communication network" or "network" may refer to any combination of communication technologies and any combination of physical networks. The term "communication network" or "network" may refer to any number of interconnected communication networks that may be operated by one or multiple network operators.

[0032] The term "application" may refer to software programming running on or executed by one or more processors of a computing device, particularly a software program executed by a mobile computing device such as a mobile phone, tablet, smartphone, or any other mobile or portable computing facility. The term "mobile application" may refer to an application executed by a mobile computing device.

[0033] As used herein, the terms "electric transmission network," "electrical transmission network," "electricity transmission network," "electric power transmission," "power line," "power transmission," and "power grid" are used interchangeably and can refer to either or both underground and overhead transmission. The term "grid" or "electric grid" or "electric network" can refer to an electric transmission and / or distribution network, and any portion of such a network between one or more generating stations and a load or customer(s).

[0034] The device that measures the electrical signal may be an electrical sensor operable to measure one or more electrical parameters, such as voltage and / or current.

[0035] The term "measurement" or "electrical measurement" may refer to any type of measurement of any electrical parameter, such as voltage, current, electric field, magnetic field, resistance, capacitance, inductance, charge, etc. The term "physical measurement" or "mechanical measurement" may refer to any type of measurement of any physical parameter other than an electrical parameter. Such parameters may be temperature, humidity, etc.

[0036] The terms "electrically coupled," or "electrically connected," or simply "connected," can refer to direct or indirect electrical contact (galvanic contact).

[0037] The terms "water content," "moisture content," "moisture," and "humidity" may be used interchangeably to refer to the amount of any aqueous phase contained within another fluid or solid.

[0038] The terms "insulator," "insulator material," "solid insulator," "paper insulator," and "paper" may be used interchangeably to refer to insulating materials used in power transformers, such as oil-impregnated cellulose insulating materials.

[0039] The term "oil" may refer to any dielectric fluid that may be used to cool the core of a power transformer.

[0040] Reference is now made to FIG. 1, which is a simplified diagram of a transformer monitoring system 10 including a transformer 11, a monitoring computer 12, and sensors, according to one exemplary embodiment.

[0041] FIG. 1 shows a simplified diagram of a cutaway view of a power transformer 11. The cutaway view reveals a tank 13 filled with oil 14 and an active portion transformer 15 immersed in the oil 14. The active portion 15 may include a magnetic core 16 around which a primary winding 17 and a secondary winding 18 are wound. The primary winding 17 and the secondary winding 18 are made from conductive wire. The primary winding 17 and the secondary winding 18 are shown in FIG. 1 in a symbolic, diagrammatic manner.

[0042] Each of the primary winding 17 and the secondary winding 18 is made from insulated wire. Insulating material, such as an insulating barrier 19, may be provided between the windings 17 and 18, between the windings 18 and the core 16, and between the windings 17 and the tank 13. The insulating material 19 may be made from cellulose, such as paper and pressboard; however, any applicable material is contemplated.

[0043] Several sensors of the transformer monitoring system 10 are installed in the transformer 11 and electrically coupled to the computer 12. A first pair of sensors, including one temperature sensor 20 and one humidity sensor 21, is installed at a first location in the oil 14, and a second pair of sensors, including one temperature sensor 22 and one humidity sensor 23, is installed at a second location in the oil 14. The temperature of the oil 14 at the first location should be different from the temperature of the oil 14 at the second location. Therefore, the temperature sensor 20 and the humidity sensor 21 are located in a higher portion of the oil 14 in the tank 13 where the temperature is relatively high, and the temperature sensor 22 and the humidity sensor 23 are located in a lower portion of the oil 14 in the tank 13 where the temperature is relatively low.

[0044] Another group of sensors includes temperature sensors 24 that may be located within the insulating material 19. It should be understood that the transformer monitoring system 10 may use any number of temperature sensors 24 to calculate the moisture content at several discrete locations within the insulating material 19 where the temperature sensors 24 are located.

[0045] Equation 1 below calculates the moisture content Wpx, ie, humidity, in the insulator 19 where the temperature sensor 24 is located based on measurements from the temperature sensors 20, 22, and 24 and the humidity sensors 21 and 23.

[0046] In Equation 1, the measurement of temperature sensor 20 is denoted by T1, the measurement of temperature sensor 22 is denoted as T2, and the measurement of temperature sensor 24 is denoted by Tx, all expressed in degrees Kalvin. RH1 denotes the measurement of humidity sensor 21, and RH2 denotes the measurement of humidity sensor 23, both given as the relative humidity of water in oil. Equation 1)

number

number

[0047] The parameters a, b, k, and d may depend on the insulating material used. For example, the parameters a, b, k, and d are given in Table A below for two exemplary types of insulating material. [Table A] The parameters 8.94 and 2254 in Equation 2 are empirical values ​​for calculating the maximum water vapor pressure of water in air Pn in Torr as a function of air temperature as follows: logPn=8.94-2254 / T

[0048] Therefore, by substituting the measured values ​​T1 (temperature sensor 20), RH1 (moisture sensor 21), T2 (temperature sensor 22), RH2 (moisture sensor 23), and Tx (temperature sensor 24) into equations 1 and 2 and selecting the appropriate parameters a, b, k, and d (related to the insulating material used), it is possible to calculate the moisture content Wpx in percent (%) in the insulating material 19 of the transformer 11.

[0049] It should be appreciated that the temperature sensor 24 may use optical temperature measurement techniques, such as a fiber optic temperature sensor that may be connected to the high voltage winding. Other types of sensors that simulate winding temperature may also be used.

[0050] It should be understood that Equations 1 and 2 and the parameters selected (a, b, k, and d) for the insulating material used can provide the moisture content of the insulating material independent of the type of oil used, the age of the oil, etc.

[0051] Reference is now made to FIG. 2, which is a simplified block diagram of a computing device 25, typically provided as a computer 12 or similar means for controlling the transformer monitoring system 10, according to one exemplary embodiment.

[0052] Optionally, the block diagram of Figure 2 may be viewed in the context of the details of previous figures. However, it should be understood that the block diagram of Figure 2 may be viewed in the context of any desired environment. Furthermore, the foregoing definitions may be equally applicable to the following description.

[0053] As shown in FIG. 2, the computing device 25 may include at least one processor unit 26, one or more memory units 27 (e.g., random access memory (RAM), non-volatile memory such as flash memory), and one or more storage units 28 (e.g., including hard disk drives and / or removable storage drives, representing floppy disk drives, magnetic tape drives, compact disk drives, flash memory devices, etc.).

[0054] Computing device 25 may also include one or more communication units 29. Such communication units 29 may use any type of communication technology, particularly RF communication technology, particularly Wi-Fi, Bluetooth, ZigBee, and any remote control communication technology such as may be used by cable device 10, to communicate with any other cable device 10, or a remote controller, remote server, or any other computing device.

[0055] Computing device 25 may also include one or more communication buses 30 connecting the above units. Computing device 25 may also include one or more control circuitry 31 for controlling other devices coupled to or included within computing device 25. Such devices may be temperature sensors 20, 22, and / or 24, and / or humidity sensors 21 and / or 23.

[0056] Computing device 25 may also include one or more computer programs 32 or computer control logic algorithms, which may be stored in either memory unit 27 and / or storage unit 28. Such computer programs, when executed, enable computing system 25 to perform various functions as described herein. Memory unit 27 and / or storage unit 28 and / or any other storage device are possible examples of tangible computer-readable media. In particular, computer program 32 may include a software program and collected data for calculating the moisture content in insulating material 19 according to Equation 1 and Equation 2 as described above.

[0057] Reference is now made to FIG. 3, which is a simplified flowchart of a process 33 for calculating moisture content in insulating material 19, according to one exemplary embodiment.

[0058] Optionally, the block diagram of Figure 3 may be viewed in the context of the details of previous figures. However, it should be understood that the block diagram of Figure 3 may be viewed in the context of any desired environment. Furthermore, the foregoing definitions may be equally applicable to the following description.

[0059] Figure 3 may illustrate a process or method 33 for calculating the moisture content in the insulating material 19 of the transformer 11 using the sensors of Figure 1. The process or method may be performed by a user using the computer 12 and may be embodied (in part or in whole) in computer code, such as the computer code 32 of the computing device 25 of Figure 2.

[0060] Process or method 33 may begin at operation 34 by identifying the type of insulating material 19 used in transformer 11. Process 33 may then proceed to operation 35 to obtain specific parameters a, b, k, and d related to the type of insulating material 19 used in transformer 11 and substitute these values ​​into code 32. For example, a user may select the specific parameters a, b, k, and d from a database of codes 32.

[0061] Process 33 or code 32 may then proceed to operation 36 and obtain temperature and moisture content measurements at two different locations in the oil within transformer 11 where the temperatures are different, for example, the temperature as measured by temperature sensor 20 and the moisture level as measured by co-located humidity sensor 21, both located at a higher position within transformer 11, and the temperature as measured by temperature sensor 22 and the moisture level as measured by co-located humidity sensor 23, both located at a lower position within transformer 11. If these two temperatures are not different in operation 37, process 33 notifies the user and stops (operation 38).

[0062] If the two temperature sensors 20 and 22 are different, the process 33 may proceed to operation 39 to obtain a temperature measurement within the insulating material within the transformer as may be measured by the temperature sensor 24 .

[0063] Process 33 may then proceed to operation 40 to calculate the moisture content in the insulating material according to equations 1 and 2, resulting in the moisture content in the region of insulating material 19 where temperature sensor 24 is located. Process 33 may then proceed to operation 41 to communicate the calculation results to a user.

[0064] It should be understood that process 33 can be performed automatically, repeatedly, and / or continuously by computer 12. Therefore, all measurements are performed repeatedly and / or continuously, and all calculations of the water vapor pressure in the insulation material are performed automatically, repeatedly, and / or continuously. It should be understood that the calculation of the moisture content or water vapor pressure in the insulation material is independent of the oil properties and therefore does not require sampling the oil or measuring oil parameters. Therefore, a user can set a threshold value for the water vapor pressure in the insulation, and the transformer monitoring system 10 can alert the user when the calculated water vapor pressure equals and / or exceeds the threshold value.

[0065] 3, process 33 may proceed to operation 42 to compare the calculated water vapor pressure to a threshold value, and if the calculated water vapor pressure is higher than the threshold value, may continue to operation 43 to alert the user. Process 33 may continually repeat operations 36-43. Alternatively, process 33 may repeat operations 36-38 and operations 39-43 independently of each other.

[0066] It should be understood that certain features that are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0067] While the description has been provided above in conjunction with specific embodiments thereof, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims. All publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art.

Claims

1. 1. A method for calculating moisture content in an insulating material of a voltage transformer, the method comprising: obtaining temperature and relative humidity measurements at two points in the oil, the two temperatures being different; and obtaining a measurement of temperature in the insulator material; Obtaining the parameters (a, b, k, and d) for a particular material of the insulator; calculating the water content in the insulating material from the relative humidity and temperature at two points in the oil using the parameters of the insulating material and according to the temperature measured in the insulating material; A method comprising:

2. The method of claim 1 , additionally comprising measuring the temperature in the insulating material using a fiber optic temperature sensor.

3. The acquired parameters are: a = 6.1, b = 0.04, k = 0.33, and d = 0.0033, and a = 3.74, b = 0.032, k = 0.63, and d = -0.0017 The method of claim 1 , wherein the method is at least one of:

4. The method of claim 1 , wherein all measurements and the calculation of the moisture content in the insulating material are performed repeatedly and / or continuously.

5. Obtaining a threshold value; comparing the calculated moisture content in the insulating material to a threshold value; alerting a user when the calculated moisture content in the insulating material is at least one of above and equal to the threshold value; 10. The method of claim 1, further comprising:

6. 1. A system for determining moisture content in an insulating material of a transformer, the system comprising: a first pair of a first temperature sensor and a first humidity sensor located at a first location in the oil inside the transformer; a second pair of a second temperature sensor and a second humidity sensor located at a second location in the oil inside the transformer, the temperature at the second location being different from the temperature at the first location; a third temperature sensor located within the insulating material; a computing device electrically coupled to the first temperature sensor, the first humidity sensor, the second temperature sensor, the second humidity sensor, and the third temperature sensor; obtaining temperature and relative humidity measurements at the two locations in the oil; obtaining a measurement of temperature in the insulator material; Obtaining the parameters (a, b, k, and d) for the insulating specific material; calculating the water content in the insulating material from the relative humidity and temperature at two points in the oil using the selected parameters of the insulating material and according to the temperature measured in the insulating material; a computing device operative to: A system comprising:

7. The system of claim 6 , wherein the temperature sensor in the insulating material is a fiber optic temperature sensor.

8. The acquired parameters are: a = 6.1, b = 0.04, k = 0.33, and d = 0.0033, and a = 3.74, b = 0.032, k = 0.63, and d = -0.0017 The system of claim 6 , wherein at least one of

9. The system of claim 6 , wherein all measurements and the calculations of the moisture content in the insulating material are performed repeatedly and / or continuously.

10. a user interface module for obtaining the threshold value; a module for comparing the calculated water content to a threshold value; a user interface module for communicating an alert to a user when the calculated moisture content in the insulating material is at least one of above and equal to the threshold value; 7. The method of claim 6, further comprising:

11. 1. A computer program product embodied on a non-transitory computer-readable medium, said computer program product comprising: obtaining temperature and relative humidity measurements at two points in the oil, the two temperatures being different; and obtaining a measurement of temperature in the insulator material; Obtaining the parameters (a, b, k, and d) for a particular material of the insulator; calculating the water content in the insulating material from the relative humidity and temperature at two points in the oil using the parameters of the insulating material and according to the temperature measured in the insulating material; 1. A computer program product comprising computer code for performing the steps of:

12. 12. The computer program product of claim 11, additionally comprising measuring the temperature in the insulating material using a fiber optic temperature sensor.

13. The acquired parameters are: a = 6.1, b = 0.04, k = 0.33, and d = 0.0033, and a = 3.74, b = 0.032, k = 0.63, and d = -0.0017 12. The computer program product of claim 11, wherein at least one of:

14. 12. The computer program product of claim 11, wherein all measurements and the calculation of the moisture content in the insulating material are performed repeatedly and / or continuously.

15. Obtaining a threshold value; comparing the calculated moisture content in the insulating material to a threshold value; alerting a user when the calculated moisture content in the insulating material is at least one of above and equal to the threshold value; 12. The computer program product of claim 11, further comprising:

Images