System and method for measuring and calculating winding hot-spot temperature of portable oil-immersed transformer

Abstract

The invention discloses a portable oil-immersed transformer winding hot-spot temperature measuring and calculating system and method, and relates to the technical field of power equipment monitoring and temperature measurement, and the method comprises the steps: collecting environment temperature data through a data collection module, and carrying out the preprocessing; data such as oil temperature actually measured by the oil temperature meter, current actually measured by the current transformer, transformer parameters and the like are input through the key input module; the winding hot-spot temperature of the transformer is calculated through a calculation module; and the control panel is used for displaying. The device is an independent handheld device, is not related to the connection with power equipment, and can be carried by a worker. Connection with a main transformer is not involved, safe and reliable operation of a power system is not affected, and personal safety of users can be guaranteed. The device is based on a winding hot-spot temperature algorithm, the influence of environment temperature is also considered, and the accuracy does not change along with the operating age limit.

Description

Technical Field

[0001] The invention relates to the technical field of power equipment monitoring and temperature measurement, and in particular to a portable oil-immersed transformer winding hot spot temperature measurement system and method. Background Art

[0002] As one of the core equipment in the power transmission and transformation process, the power transformer must ensure stable and reliable operation, and the hot spot temperature of the transformer winding is an important feature reflecting its health status. It is often necessary to obtain the hot spot temperature data of the winding in the work of thermal engineering meter inspection, oil test, high-voltage test, etc. At present, the methods for obtaining the hot spot temperature of the transformer winding mainly include direct measurement method, indirect calculation measurement method and thermal simulation measurement method.

[0003] The direct measurement method usually uses a fiber optic temperature sensor with good electrical insulation and strong anti-interference ability to directly measure the hot spot temperature of the winding near the winding. Among the power transformers currently in operation, only a small number are equipped with fiber optic temperature sensors at the factory, and most of them cannot directly obtain the hot spot temperature of the winding. Moreover, the sensor burial point is not necessarily the highest point of the winding temperature. Most power transformers use thermal simulation measurement method to measure the winding temperature.

[0004] The thermal simulation measurement method is highly dependent on the matching device. However, the shunt resistance of the matching device is prone to change with the increase of service life and the influence of the surrounding environment, which often leads to inaccurate simulated winding temperature rise. Therefore, the staff of thermal instrumentation professionals need to calibrate the winding temperature meter in each test cycle. This process requires background data acquisition and comparison with on-site temperature, which consumes a lot of manpower and time, and has low work efficiency. The indirect calculation measurement method uses the measured oil temperature, load factor and ambient temperature data, and uses an algorithm to calculate the hot spot temperature of the winding. It is easy to operate, the accuracy does not change over time, and it is highly practical.

[0005] Therefore, in order to solve the above problems, this scheme intends to develop a portable transformer winding hot spot temperature measuring device based on the indirect calculation measurement method, which is used to measure the winding hot spot temperature on site, in order to save on-site human resources and reduce working time, and improve the work efficiency of on-site staff. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention is proposed.

[0007] Therefore, the technical problem solved by the present invention is: how to solve the problems of inaccurate calculation of transformer winding hot spot temperature, non-portability of data acquisition devices, complex calculation algorithms and large data requirements in the prior art. Specifically, the invention reduces calculation errors by collecting data such as ambient temperature, inputting measured oil temperature and load current, and provides a more accurate method for measuring the hot spot temperature of the winding; at the same time, a portable data acquisition device is designed to facilitate on-site operation without affecting the operation of the transformer; in addition, a simple and efficient algorithm is used to reduce dependence on large amounts of data and improve calculation speed and accuracy.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a portable oil-immersed transformer winding hot spot temperature measurement system, which comprises the following steps:

[0009] Data acquisition module, calculation module, key input module and display module.

[0010] The data acquisition module includes a temperature sensor and an A / D conversion module.

[0011] As a preferred solution of the portable oil-immersed transformer winding hot spot temperature measurement system described in the present invention, the data acquisition module is responsible for measuring the ambient temperature of the power transformer on site and directly inputting the ambient temperature into the calculation module.

[0012] The A / D conversion module is responsible for converting the analog signal from the temperature sensor into a digital signal.

[0013] The key input module is used to receive user instructions and input the oil temperature actually measured by the oil temperature meter, the current actually measured by the current transformer, and transformer parameter data.

[0014] The calculation module calculates the hot spot temperature of the transformer winding based on the differential equation solution, using the ambient temperature obtained by the data acquisition module and the measured oil temperature, current, and transformer parameter data obtained by the key input template.

[0015] The display module displays the final result on the control panel.

[0016] Another object of the present invention is to provide a portable method for measuring the hot spot temperature of an oil-immersed transformer winding, which can quickly and accurately calculate the hot spot temperature of the transformer winding by collecting real-time data such as ambient temperature, inputting measured oil temperature and load current, and combining a simplified calculation model, thereby solving the problems in the prior art of large winding temperature calculation errors, non-portable data acquisition devices, complex algorithms and large data requirements.

[0017] In order to solve the above technical problems, the present invention provides the following technical solutions: a portable method for measuring hot spot temperature of oil-immersed transformer windings, comprising:

[0018] The ambient temperature data is collected through the data acquisition module and preprocessed; the oil temperature, current value, and transformer parameter data are input through the key input module; the transformer winding hot spot temperature is calculated through the calculation module; and it is displayed through the control panel.

[0019] As a preferred solution of the portable oil-immersed transformer winding hot spot temperature measurement method described in the present invention, the preprocessing includes converting the analog signal from the temperature sensor into a digital signal through an A / D conversion module.

[0020] As a preferred solution of the portable oil-immersed transformer winding hot spot temperature measurement method described in the present invention, wherein: the calculation of the transformer winding hot spot temperature includes solving the differential equation of the top oil temperature, which is expressed as:

[0021]

[0022] Among them, Δθ or represents the top oil temperature rise, R represents the ratio of the transformer's load loss to no-load loss, K represents the load factor, k 11 Represents the transformer characteristic parameters, τ o represents the oil time constant, θ o represents the top oil temperature, θ a Indicates the ambient temperature.

[0023] Solve for the hotspot temperature rise, expressed as,

[0024] Δθ h =Δθ h1 -Δθ h2

[0025] Among them, Δθ h1 , Δθ h2 They are respectively expressed as the first change of the winding hotspot temperature rise and the second change of the winding hotspot temperature rise.

[0026] As a preferred solution of the portable oil-immersed transformer winding hot spot temperature measurement method described in the present invention, wherein: the Δθ h1 , Δθ h2 The descriptions are expressed as,

[0027]

[0028]

[0029] The hot spot temperature is expressed as,

[0030] θ h =θ o +Δθh

[0031] Among them, k 21 , k 22 represents the transformer characteristic parameters, y represents the winding index, Δθ hr Expressed as the temperature rise of the hot spot to the top oil at rated current, τ w Expressed as the winding time constant.

[0032] As a preferred solution of the portable oil-immersed transformer winding hot spot temperature measurement method described in the present invention, wherein: the calculation of the transformer winding hot spot temperature also includes, for the running oil-immersed transformer, transforming the differential equation into a difference equation, expressed as,

[0033]

[0034] The operator D represents the difference of the relevant variables corresponding to each time period Dt, Dθ o The nth value of is calculated by the n-1th value, expressed as,

[0035] θ o(n) =θ o(n-1) +Dθ o(n)

[0036] For a running oil-immersed transformer, Δθ h1 , Δθ h2 The descriptions are expressed as,

[0037]

[0038]

[0039] In the nth time period, the total hot spot temperature rise is,

[0040]

[0041] The hot spot temperature in the nth time period is,

[0042] θ h(n) =θ o(n) +Δθ h(n) .

[0043] As a preferred solution of the portable oil-immersed transformer winding hot spot temperature measurement method described in the present invention, the display through the control panel includes: the staff inputs the on-site oil temperature meter data and current data into the measurement device, the ambient temperature is measured by the temperature sensor, and the final result is displayed on the control panel after calculation.

[0044] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the above-mentioned portable oil-immersed transformer winding hot spot temperature measurement method are implemented.

[0045] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned portable oil-immersed transformer winding hot spot temperature measurement method.

[0046] Beneficial effects of the present invention:

[0047] (1) This device is an independent handheld device that does not involve connection with power equipment and can be carried by staff.

[0048] (2) High safety: It does not involve connection with the main transformer, does not affect the safe and reliable operation of the power system, and can also ensure the personal safety of users.

[0049] (3) Stable accuracy: This device is based on the winding hot spot temperature algorithm and also takes into account the influence of ambient temperature. Its accuracy does not change with the years of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0051] Figure 1 The overall framework diagram of a portable oil-immersed transformer winding hot spot temperature measurement system provided in the first embodiment of the present invention.

[0052] Figure 2 An overall flow chart of a portable method for measuring hot spot temperature of oil-immersed transformer windings provided in accordance with the second embodiment of the present invention.

[0053] Figure 3 A thermal distribution diagram inside a transformer in a portable method for measuring hot spot temperature of windings of an oil-immersed transformer provided in a second embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0055] Example 1, reference Figure 1 , as an embodiment of the present invention, provides a portable oil-immersed transformer winding hot spot temperature measurement system, characterized in that:

[0056] A data acquisition module 100 , a calculation module 200 , a key input module 300 and a display module 400 .

[0057] The data acquisition module 100 includes a temperature sensor and an A / D conversion module.

[0058] The data acquisition module 100 is responsible for measuring the ambient temperature around the power transformer on site and directly inputting the ambient temperature data into the calculation module.

[0059] The A / D conversion module is responsible for converting the analog signal from the temperature sensor into a digital signal.

[0060] The key input module 300 is used to receive user instructions and input data such as the oil temperature actually measured by the oil temperature meter, the current actually measured by the current transformer, and transformer parameters.

[0061] The calculation module 200 calculates the hot spot temperature of the transformer winding based on the differential equation solution, using the ambient temperature data collected by the data collection module 100 and the measured oil temperature, current, transformer parameters and other data obtained by the key input module 300.

[0062] The display module 400 displays the final result on the control panel.

[0063] Example 2, reference Figure 2-Figure 3 , as an embodiment of the present invention, provides a method for measuring hot spot temperature of a portable oil-immersed transformer winding, characterized in that:

[0064] The national standard GB / T 1094.7-2008 "Power Transformer Part 7: Oil-Immersed Power Transformer Load Guidelines" provides exponential equation solution and differential equation solution as calculation methods for obtaining the hot spot temperature of transformer windings. Among them, the exponential equation solution is applicable to the case where the load change is a step function, that is, there is a sudden change at the moment of load change, such as the load change in the manufacturer's test. The differential equation method is applicable to any time-varying load and time-varying ambient temperature, such as online monitoring of transformer performance. Combined with the characteristics of large random fluctuations in oil-immersed transformer loads and complex service environments, this scheme uses the differential equation method as the calculation method for obtaining the hot spot temperature of transformer windings, as shown below.

[0065] S1: Collect ambient temperature data through the data acquisition module and perform preprocessing;

[0066] Preprocessing includes converting the analog signal from the temperature sensor into a digital signal through an A / D conversion module.

[0067] S2: Input the oil temperature measured by the oil temperature meter, the current measured by the current transformer, the transformer parameters and other data through the key input module.

[0068] S3: Calculate the hot spot temperature of the transformer winding through the calculation module.

[0069] like Figure 3 The figure shows the simplified schematic diagram of the temperature distribution in the transformer, where g t is the average winding temperature rise, H is the hot spot coefficient, H×g t represents the hot spot temperature rise, P is the hot spot temperature, and Q is the average winding temperature measured by the resistance method. Calculating the hot spot temperature of the transformer winding includes solving the differential equation for the top oil temperature, which is expressed as,

[0070]

[0071] Among them, Δθ or represents the top oil temperature rise, R represents the ratio of the transformer's load loss to no-load loss, K represents the load factor, k 11 Represents the transformer characteristic parameters, τ o represents the oil time constant, θ o represents the top oil temperature, θ a Indicates the ambient temperature.

[0072] Solve for the hotspot temperature rise, expressed as,

[0073] Δθ h =Δθ h1 -Δθ h2 (2)

[0074] Among them, Δθ h1 , Δθh2 They are respectively expressed as the first change of the winding hotspot temperature rise and the second change of the winding hotspot temperature rise.

[0075] Δθ h1 , Δθ h2 The descriptions are expressed as,

[0076]

[0077]

[0078] Substituting (3) and (4) into (2) can calculate the hot spot temperature rise.

[0079] The hot spot temperature is expressed as,

[0080] θ h =θ o +Δθ h (5)

[0081] Among them, k 21 , k 22 represents the transformer characteristic parameters, y represents the winding index, Δθ hr Expressed as the temperature rise of the hot spot to the top oil at rated current, τ w Expressed as the winding time constant.

[0082] The calculation of the hot spot temperature of the transformer winding also includes that for the running oil-immersed transformer, the ambient temperature collected by the data acquisition device and the current collection value measured by the input current transformer are discrete time series data, not a clear time function. Therefore, transforming the differential equation into a difference equation can calculate the result more effectively and accurately. The difference equation transformed from the differential equation is as follows:

[0083]

[0084] The operator D represents the difference of the relevant variables corresponding to each time period Dt, Dθ o The nth value of is calculated by the n-1th value, expressed as,

[0085] θ o(n) =θ o(n-1) +Dθ o(n) (7)

[0086] For a running oil-immersed transformer, (3) and (4) become,

[0087]

[0088]

[0089] In the nth time period, the total hot spot temperature rise is,

[0090]

[0091] The hot spot temperature in the nth time period is,

[0092] θ h(n) =θ o(n) +Δθ h(n) . (11)

[0094] To ensure the accuracy of the calculation results, the time period Dt should be as small as possible and should not be greater than half of the minimum time constant in the heating model.

[0095] S4: Display via the control panel.

[0096] Display through the control panel includes that the staff inputs the on-site oil temperature meter data and current data into the measuring device, the ambient temperature is measured by the temperature sensor, and the final result is displayed on the control panel after calculation.

[0097] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0098] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0099] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0100] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0101] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A portable oil-immersed transformer winding hot spot temperature measurement system, characterized in that: include: A data acquisition module (100), a calculation module (200), a key input module (300) and a display module (400); The data acquisition module (100) comprises a temperature sensor and an A / D conversion module.

2. A portable oil-immersed transformer winding hot spot temperature measurement system as claimed in claim 1, characterized in that: The data acquisition module (100) is responsible for measuring the ambient temperature of the power transformer on site and directly inputting the ambient temperature into the calculation module; The A / D conversion module is responsible for converting the analog signal from the temperature sensor into a digital signal; The key input module (300) is used to receive user instructions, input the oil temperature actually measured by the oil temperature meter, the current actually measured by the current transformer, and transformer parameter data; The calculation module (200) calculates the hot spot temperature of the transformer winding based on the differential equation solution and uses the ambient temperature obtained by the data acquisition module (100) and the measured oil temperature, current, and transformer parameter data obtained by the key input template; The display module (400) displays the final result on the control panel.

3. A method using a portable oil-immersed transformer winding hot spot temperature measurement system as claimed in any one of claims 1 to 2, characterized in that: include: The ambient temperature is collected through the data acquisition module and preprocessed; Input oil temperature, current value, and transformer parameter data through the key input module; Calculate the hot spot temperature of the transformer winding through the calculation module; Displayed via the control panel.

4. A portable oil-immersed transformer winding hot spot temperature measurement method as claimed in claim 3, characterized in that: The preprocessing includes converting the analog signal from the temperature sensor into a digital signal through an A / D conversion module.

5. A portable oil-immersed transformer winding hot spot temperature measurement method as claimed in claim 4, characterized in that: The calculation of the hot spot temperature of the transformer winding includes solving the differential equation of the top oil temperature, which is expressed as: Among them, Δθ or represents the top oil temperature rise, R represents the ratio of the transformer's load loss to no-load loss, K represents the load factor, k 11 Represents the transformer characteristic parameters, τ o represents the oil time constant, θ o represents the top oil temperature, θ a Indicates the ambient temperature; Solve for the hotspot temperature rise, expressed as, Dth h =Δθ h1 -Dth h2 Among them, Δθ h1 , Δθ h2 They are respectively expressed as the first change of the winding hotspot temperature rise and the second change of the winding hotspot temperature rise.

6. A portable oil-immersed transformer winding hot spot temperature measurement method as claimed in claim 5, characterized in that: The Δθ h1 , Δθ h2 The descriptions are expressed as, The hot spot temperature is expressed as, i h =θ o +Δθ h Among them, k 21 , k 22 represents the transformer characteristic parameters, y represents the winding index, Δθ hr Expressed as the temperature rise of the hot spot to the top oil at rated current, τ w Expressed as the winding time constant.

7. A portable oil-immersed transformer winding hot spot temperature measurement method as claimed in claim 6, characterized in that: The step of calculating the hot spot temperature of the transformer winding also includes, for the running oil-immersed transformer, transforming the differential equation into a difference equation, expressed as: The operator D represents the difference of the relevant variables corresponding to each time period Dt, Dθ o The nth value of is calculated by the n-1th value, expressed as, i o(n) =θ o(n-1) +Dθ o(n) For a running oil-immersed transformer, Δθ h1 , Δθ h2 The descriptions are expressed as, In the nth time period, the total hot spot temperature rise is, The hot spot temperature in the nth time period is, i h(n) =θ o(n) +Δθ h(n) 。 8. A portable oil-immersed transformer winding hot spot temperature measurement method as claimed in claim 6, characterized in that: The display through the control panel includes that the staff inputs the on-site oil temperature meter data and the current and transformer parameter data into the measuring device, the ambient temperature is measured by the temperature sensor and input into the measuring device, and the final result is displayed on the control panel after calculation.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a portable oil-immersed transformer winding hot spot temperature measurement method according to any one of claims 3 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a portable oil-immersed transformer winding hot spot temperature measurement method as described in any one of claims 3 to 8 are implemented.

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