Continuous monitoring of water content in solid insulation of transformer

Abstract

A system, method and / or computer program for measuring the moisture content in an insulating material of a transformer, comprising acquiring measurements of temperature and relative humidity at two points in the oil, where the two temperatures are different, acquiring measurements of temperature in the insulator material, acquiring parameters (a, b, k and d) of the insulator-specific material, and determining the moisture content in the insulator-specific material according to the parameters (a, b, k and d) of the insulator-specific material. And calculating the moisture content in the insulating material from the relative humidity and temperature at two points in the oil using parameters of the insulating material as a function of the measured temperature in the insulating material.

Description

TECHNICAL FIELD

[0001] The methods and apparatuses disclosed herein relate to the field of power grids, and more specifically, but not exclusively, to power stations, transformers and reactors of power stations, and substations, and more specifically, but not exclusively, to monitoring and calculating the water content in the solid insulation of transformers. BACKGROUND

[0002] Transformers are critical elements of every power station and power grid. Transformers are immersed in a dielectric liquid and comprise a magnetic core and windings. The windings comprise wires insulated by cellulose paper, such as Kraft paper. The insulation between the windings, between the windings and the core, between the windings and the oil tank containing the dielectric liquid is made of pressboard.

[0003] Water in the insulation materials adversely affects their performance. In transformers, about 99% of the water is in the cellulose insulation and 1% is in the oil. An increased amount of water in the insulation can lead to the formation of partial discharges and electrical breakdown.

[0004] Since the water content of the solid insulation cannot be measured directly, it is indirectly assessed by measuring the water content of the insulating liquid. The water absorption parameters of the insulating liquid are different and, for the same liquid, these parameters can 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 the oil within the insulation material. SUMMARY

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

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

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

[0009] According to yet another exemplary embodiment, all the measurements and the calculation of the water content in the insulation 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 one of ordinary skill in the art to which the application belongs. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting. Unless otherwise necessary or inherent within the process itself, the particular order of steps or phases of the methods and processes described in the present disclosure, including the appended drawings, is not intended or implied to be crucial to the claimed application. In many instances, the order of process steps can be changed without changing the purpose or effect of the described methods. BRIEF DESCRIPTION OF DRAWINGS

[0011] The various embodiments are described herein with reference to the accompanying drawings. The use of the same reference numbers in different figures indicates similar or identical elements.

[0012] In this regard, no attempt is made to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of the principles and concepts in which the embodiments are based. The description of the drawings made with reference to the accompanying drawings makes it apparent to those having ordinary skill in the art how the several forms and structures can be embodied in practice.

[0013] In the drawings:

[0014] Figure 1 is a simplified diagram of a transformer monitoring system including a power transformer, a monitoring computer, and sensors;

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

[0016] Figure 3 is a simplified flowchart of a process for calculating a water content in an insulation material of a transformer. DETAILED DESCRIPTION

[0017] The present embodiments include systems, methods, and / or computer programs for measuring water content of an insulation material of a transformer of an electrical grid.

[0018] The principles and operations of a system, method, and / or computer program for accurately measuring a starting point location of an electrical signal caused by an intermittent fault in a cable of an electrical grid according to several example embodiments can be better understood with reference to the following drawings and descriptions.

[0019] Before any embodiments are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. Other embodiments can be practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0020] In this document, elements of the drawings that are not described in the context of a figure and that are labeled with a number that has already been used in a previous figure to label an element of that figure have the same use and description as in the previous figure.

[0021] The drawings herein can not imply any scale. Different drawings can use different scales, and even different scales can be used within the same drawing, for example, different scales for different views of the same object, or different scales for two adjacent objects.

[0022] The phrases “at least one”, “one or more” and “and / or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of 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” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together. The term “one” or “a” means one or more. Thus, the terms “one”, “a”, “one or more” and “at least one” are used interchangeably in this document.

[0023] It is also to be noted that the terms “comprising”, “including”, “containing”, “characterized by”, and “having” are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. Specifically, these terms can imply the inclusion of stated integers or steps — and of additional integers or steps — that are not expressly stated. This limitation is also applicable to variations of the term “comprising” such as “comprise” and “comprises”.

[0024] References throughout this specification to “one implementation”, “an implementation”, or similar language mean that a particular feature, structure, or characteristic described in connection with the implementation is included in at least one embodiment of the present disclosure. The appearance of the phrase “in one implementation”, “in an implementation”, and similar language throughout this specification

[0025] The term “a plurality” is defined as two or more. The term “another” is defined as at least a second or more. The term “coupled” is defined as connected, although not necessarily directly, and not necessarily mechanically.

[0026] In this document, the term “computing device” can refer to any type of computerized machine, including, but not limited to, controllers, computers, portable computers, laptop computers, tablet computers, mobile communication devices, network servers, cloud computers, etc., and any combination thereof. Such computing devices or computerized machines can include any type or combination of devices, including, but not limited to: processors or processing devices, memory devices, storage devices, user interface devices, and / or communication devices.

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

[0028] The term “client computing device” or “client device”, “user device” can refer to any type of computing device directly used or operated by a user. Such a device can contain a user interface that can be directly used by a user, including devices for user input and / or user output. Such a device can be communicatively coupled to another computing device, such as a network server, via a communication network.

[0029] Devices for user input can include a keyboard, a pointing device such as a mouse, a microphone, a camera, a touch-sensitive pad or display, devices for user gesture control, devices for tactile user control, etc.

[0030] Devices for user output can include a display, and / or any other device for providing visual information, a speaker or earphone, and / or any other device for providing audible information, devices for providing tactile and / or haptic information, etc.

[0031] The term “communication network” or “network” can refer to any type or technology for digital communication, including but not limited to the Internet, WAN, LAN, MAN, PSDN, etc. Any of the above technologies can be wired or wireless, e.g., wireless WAN such as WiMAX, WLAN (Wi-Fi), WPAN (Bluetooth), etc. Wireless network technologies can also include PLMN and / or any type of cellular network. The term “communication network” or “network” can refer to any combination of communication technologies, as well as any combination of physical networks. The term “communication network” or “network” can refer to any number of interconnected communication networks, which can be operated by one or more network operators.

[0032] The term “application” can refer to a software program running on or executed by one or more processors of a computing device, and in particular, by mobile computing devices such as mobile phones, tablets, smartphones, etc., as well as any other mobile or portable computing facilities. The term “mobile application” can refer to an application executed by a mobile computing device.

[0033] In this document, the terms “power transmission network”, “electric transmission network”, “power transmission network”, “power transmission”, “power line”, “electric transmission”, and “grid” can be used interchangeably and relate to either or both of underground transmission and overhead transmission. The term “grid” or “power grid” or “electric grid” can refer to a power transmission grid and / or a power distribution grid, and refers to any part of such network between one or more power plants and a load or one or more consuming devices.

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

[0035] The term “measure” or “electrical measure” can 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 measure” or “mechanical measure” can refer to any type of measurement of any physical parameter other than an electrical parameter. Such parameters can be temperature, humidity, etc.

[0036] The term “electrically coupled” or “electrically connected” or simply “connected” can refer to direct or indirect electrical contact (current contact).

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

[0038] The terms “insulator”, “insulator material”, “solid insulator”, “paper insulator”, and “paper” can be used interchangeably to indicate an insulator material used in a power transformer, such as an oil-impregnated cellulose insulator material.

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

[0040] Reference is now made to Figure 1 , Figure 1 is a simplified illustration of a transformer monitoring system 10 comprising a transformer 11, a monitoring computer 12 and sensors, according to an exemplary embodiment.

[0041] Figure 1 A cross-sectional simplified illustration of a power transformer 11 is shown. The cross-section reveals an oil tank 13 filled with oil 14, and an active part transformer 15 immersed in the oil 14. The active part 15 can comprise a magnetic core 16, on which a primary winding 17 and a secondary winding 18 are wound. The primary winding 17 and the secondary winding 18 are composed of electrically conductive wire. The primary winding 17 and the secondary winding 18 are shown in a symbolic graphical manner in Figure 1 .

[0042] The primary coil 17 and the secondary coil 18 are composed of insulated wire. Insulation material, such as insulation barrier 19, can be provided between the windings 17 and 18, and between the winding 18 and the core 16, and between the winding 17 and the oil tank 13, by the insulation barrier 19. The insulation material 19 can be made of cellulose, for example paper and pressboard, however, any applicable material can be considered.

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

[0044] Another group of sensors comprises a temperature sensor 24, which can be located within the insulation material 19. It should be appreciated that the transformer monitoring system 10 can use any number of temperature sensors 24 to calculate the water content in several corresponding locations within the insulation material 19 in which the temperature sensors 24 are located.

[0045] The following equation 1 calculates the water content W px , or humidity, in the insulation 19 in which the temperature sensors 24 are located, based on the measurements of the temperature sensors 20, 22 and 24, and the humidity sensors 21 and 23.

[0046] In Equation 1, the measured value of temperature sensor 20 is represented by T1, the measured value of temperature sensor 22 is represented by T2, and the measured value of temperature sensor 24 is represented by T x , all in units of degrees Kelvin. RH1 represents the measured value of humidity sensor 21, and REE represents the measured value of humidity sensor 23, both given as relative humidity of water in the oil.

[0047] Eq. 1)

[0048] where the term v can be calculated from Equation 2.

[0049] Eq. 2)

[0050]

[0051] The parameters a, b, k, and d can depend on the insulation material used. For example, the parameters a, b, k, and d are given in Table A below for two exemplary types of insulation materials.

[0052] Table A

[0053]

[0054] The parameters 8.94 and 2254 in Equation 2 are empirical values for calculating the maximum vapor pressure P n (in units of torr) of water in air, which is a function of air temperature, as follows:

[0055] log P n = 8.94 - 2254 / T.

[0056] Thus, by substituting the measured value T1 (of temperature sensor 20), RH1 (of humidity sensor 21), the measured value T2 (of temperature sensor 22), RH2 (of humidity sensor 23), and T x x (of temperature sensor 24) into Equations 1 and 2, and selecting the appropriate parameters a, b, k, and d (for the insulation material used), the moisture content W px (in percent, %) of the insulation material 19 of transformer 11 can be calculated.

[0057] It should be understood that temperature sensor 24 can use optical temperature measurement techniques, such as a fiber optic temperature sensor that can be connected to the high voltage winding. Other types of sensors that analog the winding temperature can be used.

[0058] It should be understood that Equations 1 and 2, and the selected parameters (a, b, k, and d) for the insulation material, can provide the water content of the insulation material, independent of the type of oil used, the aging of the oil, etc.

[0059] Reference is now made to Figure 2 , Figure 2 is a simplified block diagram of a computing device 25 according to an exemplary embodiment, which is generally provided as the computer 12 or similar device controlling the transformer monitoring system 10.

[0060] As an option, the block diagram of Figure 2 may be viewed in the context of the details of the previous figures. However, of course, Figure 2 the block diagram of may be viewed in the context of any desired environment. Further, the aforementioned definitions can equally apply to the description below. Thus, the

[0061] As shown in Figure 2 , the computing device 25 can include at least one processor unit 26, one or more memory units 27 (e.g., random access memory (RAM), non-volatile memory (e.g., flash memory), etc.), and one or more storage units 28 (e.g., including a hard disk drive and / or a removable storage drive representing a floppy disk drive, magnetic tape drive, optical disk drive, flash memory device, etc.).

[0062] The computing device 25 can also include one or more communication units 29. The communication unit 29 can use any type of communications technology, in particular RF communication technology, in particular communication technologies such as Wi-Fi, Bluetooth, ZigBee, and any remote control communication technology that can be used by the cable device 10 for communication with any other cable device 10 or with a remote control, a remote server, or any other computing device.

[0063] The computing device 25 can also include one or more communication buses 30 connecting the above-described units. The computing device 25 can also include one or more control circuits 31 for controlling other devices coupled to or included in the computing device 25. Such devices can be the temperature sensors 20, 22, and / or the temperature sensor 24 and / or the humidity sensor 21, and / or the humidity sensor 23.

[0064] The computing device 25 can also include one or more computer programs 32 or computer control logic algorithms that can be stored in any of the memory units 27 and / or storage units 28. Such computer programs, when executed, enable the computing system 25 to perform various functions as set forth herein. The memory units 27 and / or storage units 28 and / or any other storage are possible examples of tangible computer-readable media. In particular, the computer programs 32 can include a software program and collected data for calculating the water content in the insulating material 19 according to equation 1 and equation 2 as described above.

[0065] Reference is now made to Figure 3 , Figure 3is a simplified flowchart of a process 33 for calculating the water content in the insulation material 19 according to one exemplary embodiment.

[0066] As an option, Figure 3 The block diagram of Fig. 1 can be understood in the context of the details of the previous figures. However, of course, Figure 3 The block diagram of Fig. 1 can be interpreted in the context of any desired environment. Moreover, the above definitions can equally apply to the following description.

[0067] Figure 3 A process or method 33 for calculating the moisture content in the insulation material 19 of a transformer 11 using sensors of the type Figure 1 may be described. The process or method can be executed by a user using a computer 12 and can (partly or fully) be embodied in computer code of a computer code 32 of a computing device 25 such as Figure 2

[0068] The process or method 33 can start from an action 34 by identifying the type of insulation material 19 used in the transformer 11. Then, the process 33 can proceed to an action 35 to acquire specific parameters a, b, k and d for the type of insulation material 19 in the transformer 11 and to introduce these values into the code 32. For example, the user can select the specific parameters a, b, k and d from a code database 32.

[0069] Then, the process 33 or code 32 can proceed to an action 36 to acquire measurements of temperature and moisture content at two different locations in the oil in the transformer 11, where the temperature is different. For example, the temperature measured by the temperature sensor 20 and the moisture level measured by the co-located humidity sensor 21, both located at a high location in the transformer 11, and the temperature measured by the temperature sensor 22 and the moisture level measured by the co-located humidity sensor 23, both located at a low location in the transformer 11. If the two temperatures are different in an action 37, the process 33 informs the user and stops (action 38).

[0070] If the two temperatures of the temperature sensors 20 and 22 are different, the process 33 can proceed to an action 39 to acquire a temperature measurement within the insulation material in the transformer, for example, can be measured by the temperature sensor 24.

[0071] The process 33 can then proceed to an action 40 to calculate the moisture content in the insulation material according to equations 1 and 2, to learn the moisture content at the area of the insulation material 19 where the temperature sensor 24 is located. Then, the process 33 can proceed to an action 41 to communicate the result of the calculation to the user.

[0072] ​It will be appreciated that the process 33 can be performed automatically, repeatedly and / or continuously by the computer 12. Thus, all measurements are performed repeatedly and / or continuously and the calculation of the water vapour pressure in the insulator material is performed automatically, repeatedly and / or continuously. It will be appreciated that the calculation of the water content or water vapour pressure in the insulator material is independent of the properties of the oil and thus there is no need to sample the oil to measure the oil parameters. Thus, a user can set a threshold for the water vapour pressure in the insulator and the transformer monitoring system 10 can alert the user when the calculated water vapour pressure is equal to and / or greater than the threshold.

[0073] Returning to Figure 3 , the process 33 can proceed to act 42 to compare the calculated water vapour pressure to a threshold and, if the calculated water vapour pressure is higher than the threshold, proceed to act 43 to alert the user. The process 33 can repeat acts 36 to 43 continuously. Alternatively, the process 33 can repeat acts 36 to 38 and acts 39 to 43 independently of each other.

[0074] It will be appreciated that, for clarity, certain features of the embodiments described in the context of separate embodiments can also be provided in combination in a single embodiment. Conversely, various features of the embodiments described in the context of a single embodiment can also be provided separately or in any appropriate

[0075] Although the description above has been provided in conjunction with specific embodiments thereof, it will be evident that many alternatives, modifications and variations will be apparent to those of ordinary skill in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated by reference in their entirety for the purpose of describing and disclosing, for example, the methodologies described in such publications, which might be used in connection with the embodiments described in this specification. In addition, the references cited herein are not to be construed as an admission that such references represent or are prior art to the present application.

Claims

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

2. The method according to claim 1, further comprising: The temperature in the insulating material is measured using a fiber optic temperature sensor.

3. The method according to claim 1, wherein The acquired parameter is at least one of the following: 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.

4. The method according to claim 1, wherein All measurements and calculations of the moisture content in the insulation material are performed in at least one of a repetitive and continuous manner.

5. The method according to claim 1, further comprising: Get the threshold value; comparing the calculated moisture content in the insulating material with the threshold value; as well as When the calculated moisture content in the insulating material is greater than or equal to the threshold, a user is warned.

6. A system for determining the moisture content in an insulation material of a transformer, the system comprising: a first pair of a first temperature sensor and a first humidity sensor, located at a first position in the oil inside the transformer; a second pair of second temperature sensors and second humidity sensors located at a second location in the oil inside the transformer, wherein the temperature at the second location is different from the temperature at the first location; a third temperature sensor located within the insulator 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, and operable to: obtaining measurements of temperature and relative humidity at two locations in the oil; obtaining a temperature measurement in the insulator material; Obtaining the material-specific parameters (a, b, k, and d) of the insulator; and The water content in the insulating material is calculated from the relative humidity and temperature at two points in the oil using selected parameters of the insulating material based on the temperature measured in the insulating material.

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

8. The system according to claim 6, wherein: The acquired parameter is at least one of the following: a=6.1, b=0.04, k=0.33, and d=0.0033; and a=3.74, b=0.032, k=0.63, d=-0.0017.

9. The system according to claim 6, wherein: All measurements and calculations of the moisture content in the insulation material are performed in at least one of a repetitive and continuous manner.

10. The method according to claim 6, further comprising: A user interface module for obtaining a threshold value; means for comparing the calculated moisture content to the threshold value; as well as A user interface module is configured to transmit an alert to a user when the calculated moisture content in the insulating material is greater than or equal to the threshold value.

11. A computer program product embodied on a non-transitory computer readable medium, comprising computer code for: Get measurements of temperature and relative humidity at two points in the oil, where The two temperatures are different; Obtaining temperature measurements in insulating materials; Obtaining specific parameters (a, b, k and d) of the insulator material; as well as The water content in the insulating material is calculated from the relative humidity and temperature at two points in the oil using parameters of the insulating material according to the temperature measured in the insulating material.

12. The computer program product of claim 11, further comprising: The temperature in the insulating material is measured using a fiber optic temperature sensor.

13. The computer program product of claim 11, wherein: The acquired parameter is at least one of the following: 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.

14. The computer program product of claim 11, wherein: All measurements and calculations of the moisture content in the insulation material are performed in at least one of a repetitive and continuous manner.

15. The computer program product of claim 11, further comprising: Get the threshold value; comparing the calculated moisture content in the insulating material with the threshold value; as well as When the calculated moisture content in the insulating material is greater than or equal to the threshold, a user is warned.

Images