Transformer current-carrying capacity determination method and device, equipment and storage medium

Abstract

The invention discloses a current-carrying capacity determination method and device of a transformer, equipment and a storage medium. The method comprises the steps of obtaining operation data and temperature data of the transformer; determining heat exchange data based on the temperature data; determining heat source data based on the operation data; determining an insulation temperature change curve based on the heat exchange data and the heat source data; and determining the current-carrying capacity of the transformer based on the insulation temperature change curve. The current-carrying capacity calculation accuracy of the transformer can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of transformer current-carrying calculation, and in particular to a method, device, equipment and storage medium for determining the current-carrying capacity of a transformer. Background Art

[0002] The current carrying capacity refers to the maximum current value that the transformer can withstand, indicating the maximum current that the transformer can deliver. The current carrying capacity of the transformer is divided into two types: common current carrying capacity and rated current carrying capacity. Common current carrying capacity refers to the maximum current value that the transformer can withstand under normal use conditions, usually 80% of the rated current carrying capacity. The rated current carrying capacity refers to the maximum current value that the transformer can withstand under long-term continuous use conditions.

[0003] In the existing current carrying capacity calculation, the transformer is assumed to operate under constant conditions to calculate the current carrying capacity of the transformer under constant conditions. However, the operating data and ambient temperature of the dry-type transformer during continuous operation are not constant. The dry-type transformer and the environment are constantly influencing each other and changing their state. This results in the existing current carrying capacity being only a reference value, which cannot reflect the actual current carrying capacity of the dry-type transformer, and the accuracy of the current carrying capacity calculation is poor. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the embodiments of the present application provide a method, device, equipment and storage medium for determining the current carrying capacity of a transformer. The heat exchange data is determined according to the temperature data of the transformer, the heat source data is determined according to the operation data of the transformer, and the core insulation temperature and the winding insulation temperature are deduced based on the heat exchange data and the heat source data to obtain the insulation temperature change curve, and the current carrying capacity of the transformer is determined by the insulation temperature change curve, so as to improve the accuracy of the current carrying capacity calculation by considering the influence of the transformer operation data and temperature data on the current carrying capacity of the transformer.

[0005] In a first aspect, an embodiment of the present application provides a method for determining the current carrying capacity of a transformer, which is applied to a controller of a transformer, wherein the transformer further comprises an iron core and a winding, a first temperature sensor is disposed on the surface of the iron core, a second temperature sensor is disposed on the surface of the winding, and the winding is connected to an electrical data collector; the electrical data collector, the first temperature sensor, and the second temperature sensor are all communicatively connected to the controller; a third temperature sensor is disposed on the surface of the transformer, and the third temperature sensor is communicatively connected to the controller; the method comprises:

[0006] Acquire the operating data and temperature data of the transformer; wherein the operating data includes winding current and operating power, and the winding current and the operating power are both collected by the electrical data collector; the temperature data includes: core insulation temperature, winding insulation temperature and ambient temperature, the core insulation temperature is collected by the first temperature sensor, the winding insulation temperature is collected by the second temperature sensor, and the ambient temperature is collected by the third temperature sensor;

[0007] Based on the temperature data, heat exchange data is determined; the heat exchange data includes a core heat flow rate and a winding heat flow rate;

[0008] Based on the operation data, heat source data is determined; the heat source data includes core heating power and winding heating power;

[0009] Based on the heat exchange data and the heat source data, determining an insulation temperature change curve; the insulation temperature change curve includes an iron core insulation temperature change curve and a winding insulation temperature change curve;

[0010] Based on the insulation temperature variation curve, the current carrying capacity of the transformer is determined.

[0011] In a second aspect, an embodiment of the present application provides a current carrying capacity determination device, which is applied to a controller of a transformer, wherein the transformer further comprises an iron core and a winding, a first temperature sensor is disposed on the surface of the iron core, a second temperature sensor is disposed on the surface of the winding, and the winding is connected to an electrical data collector; the electrical data collector, the first temperature sensor, and the second temperature sensor are all communicatively connected to the controller; a third temperature sensor is disposed on the surface of the transformer, and the third temperature sensor is communicatively connected to the controller; the device comprises:

[0012] an acquisition unit, configured to acquire operation data and temperature data of the transformer; wherein the operation data includes winding current and operation power, and both the winding current and the operation power are acquired through the electrical data collector; the temperature data includes: core insulation temperature, winding insulation temperature and ambient temperature, and the core insulation temperature is acquired through the first temperature sensor, the winding insulation temperature is acquired through the second temperature sensor, and the ambient temperature is acquired through the third temperature sensor;

[0013] A processing unit, configured to determine heat exchange data based on the temperature data; the heat exchange data includes a core heat flow rate and a winding heat flow rate;

[0014] Based on the operation data, heat source data is determined; the heat source data includes core heating power and winding heating power;

[0015] Based on the heat exchange data and the heat source data, determining an insulation temperature change curve; the insulation temperature change curve includes an iron core insulation temperature change curve and a winding insulation temperature change curve;

[0016] Based on the insulation temperature variation curve, the current carrying capacity of the transformer is determined.

[0017] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a processor and a memory, the processor being connected to the memory, the memory being used to store a computer program, and the processor being used to execute the computer program stored in the memory, so that the electronic device performs the method described in the first aspect.

[0018] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method described in the first aspect.

[0019] In a fifth aspect, an embodiment of the present application provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program, and the computer program product is operable to cause a computer to execute the method described in the first aspect.

[0020] Implementing the embodiments of the present application has the following beneficial effects:

[0021] In an embodiment of the present application, the core insulation temperature is obtained by a first temperature sensor deployed on the surface of the core of the transformer, the winding current and operating power are obtained by an electrical data collector connected to the winding, the winding insulation temperature is obtained by a second temperature sensor deployed on the surface of the winding, and the ambient temperature is obtained by a third temperature sensor deployed on the surface of the transformer, thereby obtaining the operating data and temperature data of the transformer. Then, based on the temperature data, the heat exchange data of the transformer is determined, and based on the operating data, the heat source data of the transformer is determined. Further, based on the heat exchange data and the heat source data, the insulation temperature change curve is determined. Finally, based on the insulation temperature change curve, the current carrying capacity of the transformer is determined. Therefore, in combination with the operating data and temperature data of the transformer, the transformer is subjected to heat exchange calculation and heat source data calculation, and the insulation temperature change curve of the transformer under the current operating data and temperature data can be deduced, and based on the insulation temperature change curve, the current carrying capacity of the transformer is determined, and the current carrying capacity corresponds to the operating data and temperature data of the transformer, thereby improving the accuracy of the current carrying capacity calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic diagram of a system for determining the current carrying capacity of a transformer provided in an embodiment of the present application;

[0024] Figure 2 A schematic flow chart of a method for determining the current carrying capacity of a transformer provided in an embodiment of the present application;

[0025] Figure 3 A block diagram of the functional units of a current carrying capacity determination device provided in an embodiment of the present application;

[0026] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] The terms "first", "second", "third", etc. in the specification and claims of the present application and the drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0029] Reference to "embodiments" herein means that a particular feature, result, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] First, see Figure 1 , Figure 1A schematic diagram of a transformer current carrying capacity determination system provided in an embodiment of the present application. Figure 1 As shown, the current carrying capacity determination system of the transformer includes: a transformer, a first temperature sensor, a second temperature sensor, a third temperature sensor, and an electrical data collector.

[0031] Among them, the transformer is an electrical device that uses the principle of electromagnetic induction to change the AC voltage. The transformer includes: a controller, an iron core and a winding. A first temperature sensor is deployed on the surface of the iron core, a second temperature sensor is deployed on the surface of the winding, and the winding is connected to an electrical data collector; the electrical data collector, the first temperature sensor and the second temperature sensor are all connected to the controller for communication; a third temperature sensor is deployed on the surface of the transformer, and the third temperature sensor is connected to the controller for communication. Figure 1 The transformer shown is a three-phase transformer, and the first temperature sensor is deployed on the surface of the iron core of the three-phase transformer. In the embodiment of the present application, the iron core can be any iron core in the transformer, and the first temperature sensor is the first temperature sensor corresponding to the iron core. The iron core is the magnetic circuit part of the transformer, which is usually stacked with silicon steel sheets. The shape of the iron core is generally core-type and shell-type. The core-type iron core is a winding wrapped iron core, while the shell-type iron core is an iron core wrapped winding, such as Figure 1 The iron core shown is a core-type iron core, and the winding is wrapped around the iron core. The winding is the circuit part of the transformer, which is wound by insulated wire. The winding includes a primary winding and a secondary winding. The primary winding is connected to the power supply. When the current of the power supply changes, an induced magnetic field is generated in the coil of the primary winding, thereby generating an induced electromotive force in the coil of the secondary winding to achieve the function of voltage transformation. Figure 1 The transformer shown includes three primary windings and three secondary windings, and each primary winding and each secondary winding are provided with a second temperature sensor. The winding in the embodiment of the present application can be any one of the three primary windings and the three secondary windings, and the second temperature sensor is the second temperature sensor corresponding to the winding. The electrical data collector is connected to any one of the windings through a wire, and the operating data of any one of the windings can be collected. According to the cooling method, the transformer can be divided into an oil-immersed transformer and a dry-type transformer. In the oil-immersed transformer, the iron core and the winding are immersed in insulating oil, and the heat generated by the transformer is transferred to the outside through the insulating oil for heat dissipation. In the dry-type transformer, the iron core and the winding are not immersed in a liquid medium, and the heat is dissipated by natural cooling methods such as air convection or by installing a fan. The embodiment of the present application is mainly explained by taking the transformer as a dry-type transformer as an example.

[0032] Among them, the controller of the transformer can be a processor chip for state monitoring, voltage regulation, circuit protection, data processing and data communication, including: a central processing unit (CPU), a digital signal processor (DSP), a field programmable gate array (FPGA), etc. The controller can be an electronic device integrating the above-mentioned processor chip, including: a computer, a smart phone, etc. The first temperature sensor is used to collect the core insulation temperature, the second temperature sensor is used to collect the winding insulation temperature, the third temperature sensor is used to collect the ambient temperature, and the electrical data collector is used to collect the operation data of the transformer. In an embodiment of the present application, the controller can obtain the core insulation temperature from the first temperature sensor, the winding insulation temperature from the second temperature sensor, the ambient temperature from the third temperature sensor, and the operation data of the transformer from the electrical data collector. And according to the operation data and temperature data, the current carrying capacity of the transformer is determined.

[0033] It should be noted that in the existing method for determining the current carrying capacity of a transformer, it is usually assumed that the transformer operates at constant operating data and temperature data, and the current carrying capacity of the transformer is calculated when the transformer operates at constant operating data and temperature data. However, the operating data and temperature data of the transformer are changing at any time, resulting in inaccurate calculation of the current carrying capacity of the transformer.

[0034] To this end, the controller used in the current carrying capacity determination system of the above-mentioned transformer, in the current carrying capacity determination method of the transformer of the present application, obtains the operating data and temperature data of the transformer; wherein the operating data includes the winding current and the operating power, and the winding current and the operating power are both collected by the electrical data collector; the temperature data includes: the core insulation temperature, the winding insulation temperature and the ambient temperature, the core insulation temperature is collected by the first temperature sensor, the winding insulation temperature is collected by the second temperature sensor, and the ambient temperature is collected by the third temperature sensor;

[0035] The controller determines heat exchange data based on the temperature data; the heat exchange data includes the heat flow rate of the core and the heat flow rate of the winding;

[0036] The controller determines the heat source data based on the operation data; the heat source data includes the heating power of the core and the heating power of the winding;

[0037] The controller determines the insulation temperature change curve based on the heat exchange data and the heat source data; the insulation temperature change curve includes the core insulation temperature change curve and the winding insulation temperature change curve;

[0038] The controller determines the current carrying capacity of the transformer based on the insulation temperature variation curve.

[0039] It can be seen that in the current carrying capacity determination system applied to the above transformer, the controller can obtain the operation data and temperature data of the transformer, determine the heat exchange data of the transformer based on the temperature data, and determine the heat source data of the transformer based on the operation data. Then, the insulation temperature change curve of the transformer is derived based on the heat exchange data and the heat source data, and the current carrying capacity of the transformer is determined based on the insulation temperature change curve. The current carrying capacity corresponds to the operation data and temperature data of the transformer, thereby improving the accuracy of the current carrying capacity calculation.

[0040] See also Figure 2 , Figure 2 A flow chart of a method for determining the current carrying capacity of a transformer provided in an embodiment of the present application. The method is applied to a controller of a transformer, and the transformer also includes an iron core and a winding. A first temperature sensor is disposed on the surface of the iron core, and a second temperature sensor is disposed on the surface of the winding, and the winding is connected to an electrical data collector. The electrical data collector, the first temperature sensor, and the second temperature sensor are all connected to the controller in communication. A third temperature sensor is disposed on the surface of the transformer, and the third temperature sensor is connected to the controller in communication. This includes but is not limited to the following steps:

[0041] 201: Obtain the operation data and temperature data of the transformer.

[0042] In an embodiment of the present application, the operating data includes winding current and operating power, and the winding current and operating power are collected by an electrical data collector. The temperature data includes: core insulation temperature, winding insulation temperature and ambient temperature, the core insulation temperature is collected by a first temperature sensor, the winding insulation temperature is collected by a second temperature sensor, and the ambient temperature is collected by a third temperature sensor. Among them, the core insulation temperature is the maximum temperature of the core surface when the insulating material in the core maintains insulation, and can also be regarded as the hot spot temperature of the core. The winding insulation temperature is the maximum temperature of the winding surface when the insulating material in the winding maintains insulation, and can also be regarded as the hot spot temperature of the winding. Optionally, the winding current can be a low-voltage winding current or a high-voltage winding current, which is not limited in this application. The operating data can also include a high-voltage winding voltage and a low-voltage winding voltage.

[0043] Optionally, there may be abnormal values, missing values, etc. in the winding current and operating power collected by the electrical data collector, the core insulation temperature collected by the first temperature sensor, the winding insulation temperature collected by the second temperature sensor, and the ambient temperature collected by the third temperature sensor. The controller can perform data cleaning and preprocessing on the collected data, including: removing abnormal values, interpolating missing values, etc. Among them, the controller can synchronously store the operating data and temperature data obtained from the electrical data collector, the first temperature sensor, the second temperature sensor, and the third temperature sensor in the database, and the synchronization method includes homogeneous database synchronization or heterogeneous database synchronization. The controller can query the operating data and temperature data of the transformer from the database by means of clustered column storage index.

[0044] 202: Determine heat exchange data based on the temperature data.

[0045] In the embodiment of the present application, the heat exchange data includes the core heat flow rate and the winding heat flow rate. The core heat flow rate indicates the amount of heat transferred through the core surface by conduction, convection, radiation, etc. per unit time. The winding heat flow rate indicates the amount of heat transferred through the winding surface by conduction, convection, radiation, etc. per unit time. Among them, the heat exchange method of the dry-type transformer is mainly convection heat exchange, and the controller can determine the heat exchange data according to the temperature data of the transformer.

[0046] Exemplarily, determining heat exchange data based on temperature data may include:

[0047] Obtain the transformer type, core thickness, core heat dissipation area, winding thickness, and winding heat dissipation area of ​​the transformer;

[0048] Based on the temperature data, determine the heat exchange efficiency coefficient corresponding to the transformer type;

[0049] Determine the core heat flow rate based on the heat exchange efficiency coefficient, core heat dissipation area, core thickness, core insulation temperature and ambient temperature;

[0050] The winding heat flow rate is determined based on the heat exchange efficiency coefficient, the winding heat dissipation area, the winding thickness, the winding insulation temperature and the ambient temperature.

[0051] In an embodiment of the present application, transformer types include: self-cooling transformers, air-cooled transformers, transformers with air ducts and transformers without air ducts, and so on. Different transformer types correspond to different heat exchange efficiency coefficients. The heat exchange efficiency coefficient is usually between 0.6 and 0.9, which is used to indicate the size of the heat exchange efficiency and is affected by factors such as transformer insulation materials, cooling methods, and ambient humidity. The heat dissipation area of ​​the core is the sum of the top area of ​​the upper iron yoke, the side surface areas of the upper and lower iron yokes, the covering area, and the core yoke air duct surface area. The heat dissipation area of ​​the winding is the sum of the horizontal air duct heat dissipation area, the internal winding surface covering area, and the vertical air duct heat dissipation area.

[0052] Specifically, the controller first obtains the transformer type, core thickness, core heat dissipation area, winding thickness, and winding heat dissipation area of ​​the transformer. The transformer type, core thickness, core heat dissipation area, winding thickness, and winding heat dissipation area of ​​the transformer are all parameter data when the transformer leaves the factory and are stored in a database. The controller can directly obtain the above data from the database. According to the temperature data, the heat exchange efficiency coefficient corresponding to the transformer type can be determined.

[0053] Optionally, the controller first obtains multiple historical temperature data and multiple historical heat exchange efficiency coefficients corresponding to the transformer type, and the historical temperature data includes: multiple historical ambient temperatures, multiple historical winding insulation temperatures, and multiple historical core insulation temperatures. Then, a preset deep learning model is obtained, and the preset deep learning model can be a convolutional neural network model. The multiple historical temperature data are used as input and the multiple historical heat exchange efficiency coefficients are used as output, and the preset deep learning model is trained to obtain a target deep learning model. Finally, the ambient temperature, winding insulation temperature, and core insulation temperature are input into the target deep learning model to obtain the heat exchange efficiency coefficient.

[0054] It should be noted that the heat flux can be expressed as the ratio of the heat passing through unit area and unit thickness to the differential of time, or as the product of heat flux density and area. From this, the calculation formulas for the heat flux of the core and the heat flux of the winding can be derived.

[0055] The controller may determine the core heat flow rate based on the heat exchange efficiency coefficient, the core heat dissipation area, the core thickness, the core insulation temperature and the ambient temperature. Specifically, the core heat flow rate may be determined by the following formula (1):

[0056]

[0057] in, represents the core heat flux, α represents the heat exchange efficiency coefficient, S0 represents the core heat dissipation area, T0 represents the core insulation temperature, T amb represents the ambient temperature, and d0 represents the core thickness.

[0058] Finally, the controller can determine the winding heat flow rate based on the heat exchange efficiency coefficient, the winding heat dissipation area, the winding thickness, the winding insulation temperature and the ambient temperature. Specifically, the winding heat flow rate can be determined by the following formula (2):

[0059]

[0060] in, It represents the heat flow rate of the winding, S1 represents the heat dissipation area of ​​the winding, T1 represents the insulation temperature of the winding, and d1 represents the thickness of the winding.

[0061] It can be seen that by obtaining the transformer type, core thickness, core heat dissipation area, winding thickness and winding heat dissipation area of ​​the transformer, based on the temperature data, the heat exchange efficiency coefficient corresponding to the transformer type can be determined. Then, based on the heat exchange efficiency coefficient, core heat dissipation area, core thickness, core insulation temperature and ambient temperature, the core heat flow rate is determined. Finally, based on the heat exchange efficiency coefficient, winding heat dissipation area, winding thickness, winding insulation temperature and ambient temperature, the winding heat flow rate is determined. Therefore, the heat exchange data corresponding to the transformer can be determined according to the temperature data of the transformer, and the insulation temperature change of the transformer can be determined according to the heat exchange data to deduce the current carrying capacity of the transformer under the insulation temperature change, thereby improving the accuracy of the current carrying capacity calculation.

[0062] 203: Determine heat source data based on the operation data.

[0063] In an embodiment of the present application, the heat source data includes the core heating power and the winding heating power. It should be noted that the heat sources that generate heat during the operation of the dry-type transformer are the core and the winding. The main reason for the heat generated by the core is iron loss. The iron loss is the heat loss caused by the change of magnetic flux in the magnetic circuit of the transformer, also known as induction loss. The loss power corresponding to the iron loss is the core loss power. The main reason for the heat generated by the winding is copper loss. The copper loss is the heat loss generated by the current in the coil of the winding, also known as resistance loss. The loss power corresponding to the copper loss is the winding loss power. Therefore, the controller determines the core loss power to determine the core heating power. The controller determines the winding loss power based on the operating data to determine the winding heating power.

[0064] Exemplarily, determining heat source data based on the operating data may include:

[0065] Acquire a plurality of first component materials and a plurality of first masses corresponding to the iron core, and a plurality of second component materials and a plurality of second masses corresponding to the winding;

[0066] determining a heat capacity of each of the plurality of first component materials to obtain a plurality of first heat capacities;

[0067] determining a ratio of each first mass in the plurality of first masses to a total mass of the plurality of first masses, to obtain a plurality of first ratios;

[0068] determining a first effective heat capacity of the core based on the plurality of first heat capacities and the plurality of first ratios;

[0069] Determine the no-load power of the transformer based on the operating power, and use the no-load power as the core loss power;

[0070] Determining the core heating power based on the first effective heat capacity and the core loss power;

[0071] determining a heat capacity of each second component material in the plurality of second component materials to obtain a plurality of second heat capacities;

[0072] determining a ratio of each second mass in the plurality of second masses to the total mass of the plurality of second masses, to obtain a plurality of second ratios;

[0073] determining a second effective thermal capacity of the winding based on the plurality of second thermal capacities and the plurality of second ratios;

[0074] Based on the winding current, determine the winding power loss;

[0075] The winding heating power is determined based on the second effective heat capacity and the winding loss power.

[0076] In the embodiment of the present application, the plurality of first component materials correspond one-to-one to the plurality of first masses, and the plurality of second component materials correspond one-to-one to the plurality of second masses.

[0077] Specifically, the controller first obtains a plurality of first component materials corresponding to the iron core and a plurality of first masses corresponding to the plurality of first component materials. For example, the component materials of the iron core are usually the iron core conductor part, the internal insulation part and the external insulation resin. And obtains a plurality of second component materials corresponding to the winding and a plurality of second masses corresponding to the plurality of second component materials. For example, the component materials of the winding are usually the winding metal conductor part, the winding internal insulation paper part and the external insulation resin. The plurality of first component materials, the plurality of first masses, the plurality of second component materials and the plurality of second masses are all factory parameters of the transformer, which are stored in the database and can be obtained by the controller from the database.

[0078] Then, the controller determines the heat capacity of each first component material among the multiple first component materials to obtain multiple first heat capacities. It should be noted that the first heat capacity corresponding to each first component material is the material's own property, that is, the corresponding relationship between the first component material and the first heat capacity can be preset according to the material's own property. Next, the controller determines the total mass of the multiple first masses, and uses the ratio of each first mass to the total mass of the multiple first masses as the first ratio of the first component material corresponding to the first mass to obtain multiple first ratios. Finally, the controller multiplies the first heat capacity corresponding to each first component material among the multiple first component materials by the first ratio to obtain multiple first products, and uses the sum of the multiple first products as the first effective heat capacity of the iron core.

[0079] Further, the controller determines the no-load power of the transformer according to the operating power. It can be understood that the no-load power of the transformer can be approximately regarded as iron loss. The no-load power is a factory parameter of the transformer. It is affected by the operating voltage fluctuation. The mapping relationship between the no-load power and the operating voltage can be preset according to the actual test results. The controller can determine the operating voltage of the transformer according to the operating power and winding current of the transformer, and then determine the no-load power of the transformer according to the operating voltage of the transformer, and use the no-load power as the core loss power. Finally, the controller can determine the core heating power according to the core loss power and the first effective heat capacity. The mapping relationship between the core loss power and the first effective heat capacity and the core heating power can be preset according to the actual test results.

[0080] Optionally, after determining the first effective heat capacity of the iron core, the controller may also multiply the product of the total mass of the plurality of first masses and the first effective heat capacity by the heat flux of the iron core to obtain the heating power of the iron core.

[0081] Then, the controller determines the heat capacity of each second component material in the plurality of second component materials to obtain a plurality of second heat capacities. It should be noted that the second heat capacity corresponding to each second component material is a material property itself, that is, the correspondence between the second component material and the second heat capacity can be preset according to the material property itself. Next, the controller determines the total mass of the plurality of second masses, and uses the ratio of each second mass to the total mass of the plurality of second masses as the second ratio of the second component material corresponding to the second mass, to obtain a plurality of second ratios. Finally, the controller multiplies the second heat capacity corresponding to each second component material in the plurality of second component materials by the second ratio to obtain a plurality of second products, and uses the sum of the plurality of second products as the second effective heat capacity of the winding.

[0082] Furthermore, the controller may determine the winding loss power based on the winding current of the transformer.

[0083] Exemplarily, determining the winding power loss based on the winding current may include:

[0084] Obtain the corresponding resistance value, resistance temperature coefficient and factory winding insulation temperature of the winding;

[0085] The winding power loss is determined by the following formula (3):

[0086] P Cu =I 2 R Cu [1+TCR(T Cu0 -T Cu )] Formula (3)

[0087] Among them, P Cu represents the winding power loss, I represents the winding current, R Cu represents the resistance value, TCR represents the temperature coefficient of resistance, T Cu0 Indicates the factory winding insulation temperature, T Cu Indicates the winding insulation temperature. The resistance temperature coefficient indicates the ratio of the change in the winding insulation temperature to the winding insulation temperature when the winding insulation temperature increases by one unit temperature.

[0088] Specifically, the controller first obtains the resistance value, resistance temperature coefficient and factory winding insulation temperature corresponding to the winding. The resistance value, resistance temperature coefficient and factory winding insulation temperature are all factory parameters of the transformer, which are stored in the database and can be obtained by the controller from the database. Then, the winding loss power is determined by formula (3), so that the winding heating power can be determined according to the winding loss power, so as to deduce the winding insulation temperature, determine the current carrying capacity of the transformer, and improve the accuracy of the current carrying capacity calculation.

[0089] Finally, the controller can determine the winding heating power based on the winding power loss and the second effective heat capacity. The mapping relationship between the winding power loss and the second effective heat capacity and the winding heating power can be preset according to actual test results.

[0090] Optionally, after determining the second effective heat capacity of the winding, the controller may also multiply the product of the total mass of the plurality of second masses and the second effective heat capacity by the heat flow rate of the winding to obtain the heating power of the winding.

[0091] It can be seen that the controller can determine the first effective heat capacity of the core according to the multiple first heat capacities and the multiple first masses corresponding to the multiple components of the core, and then determine the no-load power of the transformer according to the operating power, and use the no-load power as the core loss power, and determine the core heating power based on the first effective heat capacity and the core loss power. Next, the second effective heat capacity of the winding is determined according to the multiple second heat capacities and the multiple second masses corresponding to the multiple second components of the winding, and further, the winding loss power is determined according to the winding current, and the winding heating power can be determined based on the second effective heat capacity and the winding loss power. In this way, the heat source data of the transformer can be determined, and the insulation temperature of the transformer can be deduced according to the heat source data, and finally the current carrying capacity of the transformer is determined, which fully considers the influence of the temperature change of the transformer and improves the accuracy of the current carrying capacity calculation.

[0092] 204: Determine an insulation temperature variation curve based on the heat exchange data and the heat source data.

[0093] In the embodiment of the present application, the insulation temperature change curve includes a core insulation temperature change curve and a winding insulation temperature change curve. The core insulation temperature change curve is used to indicate the change of the core insulation temperature with temperature, and the winding insulation temperature change curve is used to indicate the change of the winding insulation temperature with temperature. It should be noted that the heat balance relationship corresponding to the transformer can be established based on the heat exchange data and the heat source data, so as to determine the change relationship between the core insulation temperature and the winding insulation temperature in the transformer, so as to determine the core insulation temperature change curve and the winding insulation temperature change curve.

[0094] Exemplarily, determining the insulation temperature variation curve based on the heat exchange data and the heat source data may include:

[0095] Obtain the temperature change limit value of the transformer;

[0096] Based on the heat flow rate of the iron core and the heating power of the iron core, a first heat balance relationship is established; based on the first heat balance relationship, a temperature change relationship of the iron core insulation is determined;

[0097] Based on the temperature change limit value and the relationship between the core insulation temperature change, the core insulation temperature is deduced to obtain multiple expected core insulation temperatures;

[0098] Perform curve fitting on multiple expected core insulation temperatures to obtain a core insulation temperature variation curve;

[0099] Based on the heat flow rate of the winding and the heating power of the winding, a second heat balance relationship is established; based on the second heat balance relationship, a winding insulation temperature change relationship is determined;

[0100] Based on the temperature change limit value and the relationship between the winding insulation temperature change, the winding insulation temperature is deduced to obtain multiple expected winding insulation temperatures;

[0101] Curve fitting is performed on multiple expected winding insulation temperatures to obtain a winding insulation temperature variation curve.

[0102] In the embodiment of the present application, the temperature change limit value is a factory parameter of the transformer, indicating the maximum value of the temperature rise allowed by the transformer during operation, and is stored in the database. Specifically, the controller can obtain the temperature change limit value of the transformer from the database.

[0103] Then, the controller can establish a first heat balance relationship based on the core heat flow rate and the core heating power. Based on the first heat balance relationship, the core insulation temperature change relationship can be determined, and the core insulation temperature change relationship can be simplified and expressed by the following formula (4):

[0104]

[0105] Where dt represents the differential with respect to time, C Fe Represents the first effective heat capacity, m Fe represents the total mass of the plurality of first masses, ΔT0 represents the change in the insulation temperature of the core, and P0 represents the heating power of the core.

[0106] Furthermore, the controller deduce the core insulation temperature based on the temperature change limit value and the core insulation temperature change relationship, and deduce multiple expected core insulation temperatures when the core insulation temperature changes from the current core insulation temperature to the temperature change limit value. Curve fitting is performed on the multiple expected core insulation temperatures to obtain a core insulation temperature change curve.

[0107] Then, the controller establishes a second heat balance relationship based on the heat flow rate of the winding and the heating power of the winding. Based on the second heat balance relationship, the winding insulation temperature change relationship can be determined, and the winding insulation temperature change relationship can be simplified and expressed by the following formula (5):

[0108]

[0109] Among them, C Cu Represents the second effective heat capacity, m Cu represents the total mass of multiple second masses, ΔT1 represents the change in the insulation temperature of the winding, and P1 represents the heating power of the winding.

[0110] Furthermore, the controller deduces the winding insulation temperature based on the temperature change limit value and the winding insulation temperature change relationship, and deduces multiple expected winding insulation temperatures when the winding insulation temperature changes from the current winding insulation temperature to the temperature change limit value. Curve fitting is performed on the multiple expected winding insulation temperatures to obtain a winding insulation temperature change curve.

[0111] It can be seen that the first heat balance relationship is established through the core heat flux rate and the core heating power, and the core insulation temperature change relationship is determined according to the first heat balance relationship. The core insulation temperature can be deduced according to the temperature change limit value of the transformer and the core insulation temperature change relationship to obtain multiple expected core insulation temperatures. By curve fitting the multiple expected core insulation temperatures, the core insulation temperature change curve can be obtained. Then, based on the winding heat flux rate and the winding heating power, a second heat balance relationship can be established, and the winding insulation temperature change relationship can be determined according to the second heat balance relationship. According to the temperature change limit value and the winding insulation temperature change relationship, the winding insulation temperature can be deduced to obtain multiple expected winding insulation temperatures. By curve fitting the multiple expected winding insulation temperatures, the winding insulation temperature change curve can be obtained. Therefore, according to the core insulation temperature change curve and the winding insulation temperature change curve, the current carrying capacity of the transformer can be determined. The current carrying capacity fully considers the core insulation temperature change and the winding insulation temperature change, and improves the accuracy of the current carrying capacity calculation.

[0112] 205: Determine the current carrying capacity of the transformer based on the insulation temperature variation curve.

[0113] In the embodiment of the present application, the current carrying capacity of the transformer may include the current carrying capacity corresponding to the thermal balance point and / or the current carrying capacity corresponding to the critical point. The thermal balance point is the sample point corresponding to the moment when the core heat flow rate and the winding heat flow rate are both 0, and the critical point is the sample point when the core insulation temperature and the winding insulation temperature both reach the maximum insulation temperature and the maximum insulation temperature change value corresponding to the heat resistance grade of the transformer.

[0114] Exemplarily, when the current carrying capacity of the transformer includes the current carrying capacity corresponding to the thermal balance point, determining the current carrying capacity of the transformer based on the insulation temperature variation curve may include:

[0115] Acquire a plurality of first sample points and a plurality of first moments with a slope of 0 in the core insulation temperature variation curve;

[0116] According to the multiple first moments, obtaining multiple second sample points from the winding insulation temperature variation curve;

[0117] Determine the slopes of a plurality of second sample points in the winding insulation temperature variation curve, and take the second sample point with a slope of 0 as a thermal equilibrium point;

[0118] Get the thermal equilibrium point limit value;

[0119] Based on the thermal balance point limit value, determine the maximum winding heating power corresponding to the thermal balance point;

[0120] Determine the current carrying capacity based on the maximum winding heating power.

[0121] In the embodiment of the present application, multiple first sample points correspond to multiple first moments one by one. It should be noted that at the thermal equilibrium point, the heat flowing into the transformer plus the heat generated by the transformer itself is equal to the heat flowing out of the transformer, then the transformer is in a thermal steady state, and the temperature of any node does not change with time. At this time, the dry-type transformer is operating in a stable state, and as long as the core insulation temperature and the winding insulation temperature in the transformer are not higher than the temperature corresponding to the thermal equilibrium point, it can operate stably for a long time.

[0122] Specifically, the controller first determines the slope corresponding to each sample point in the core insulation temperature change curve, and takes the sample point with a slope of 0 in the core insulation temperature change curve as the first sample point to obtain multiple first sample points. And obtain multiple first moments corresponding to the multiple first sample points. Then, according to the multiple first moments, obtain multiple second sample points from the winding insulation temperature change curve, and determine the slope corresponding to each second sample point in the winding insulation temperature change curve. Further, the controller takes the point with a slope of 0 in the multiple second sample points as the thermal equilibrium point. It can be understood that there may be multiple second sample points with a slope of 0 in the multiple second sample points. The controller will obtain multiple second moments corresponding to the multiple second sample points with a slope of 0, and take the second sample point with the smallest slope of 0 in the second moment as the thermal equilibrium point.

[0123] Furthermore, the controller may obtain a thermal balance point limit value from a database, and the thermal balance point limit value is used to limit the change in the winding insulation temperature curve, and the insulation temperature change at this time is limited to 0. Based on the thermal balance point limit value, the controller may determine the maximum winding heating power corresponding to the thermal balance point by applying the convergence theorem, and determine the maximum winding loss power according to the maximum winding heating power. Finally, the controller may determine that the operating current corresponding to the maximum winding loss power is the current carrying capacity corresponding to the thermal balance point, that is, the current carrying capacity of the transformer.

[0124] It can be seen that by determining multiple first moments corresponding to multiple first sample points with a slope of 0 in the core insulation temperature change curve, and obtaining multiple second sample points in the winding insulation temperature change curve according to the multiple first moments, the second sample point with a slope of 0 among the multiple second sample points is used as the thermal balance point. Then, according to the thermal balance point limit value, the maximum winding heating power corresponding to the thermal balance point is determined, and the current carrying capacity is determined according to the maximum winding heating power. By operating the transformer at the current carrying capacity corresponding to the thermal balance point, not only can the insulation degradation be reduced, but also the dielectric strength, the structural integrity of the coil, the winding noise, the heat transfer and the partial discharge can be improved, so as to ensure the stable operation of the dry-type transformer and extend the service life of the transformer. At the same time, the current carrying capacity takes into account the core insulation temperature change and the winding insulation temperature change, and improves the accuracy of the current carrying capacity calculation.

[0125] Exemplarily, when the current carrying capacity of the transformer includes the current carrying capacity corresponding to the critical point, determining the current carrying capacity of the transformer based on the insulation temperature variation curve may include:

[0126] Get the thermal resistance grade of the insulation material in the transformer;

[0127] Based on the heat resistance grade, determine the maximum insulation temperature and the maximum insulation temperature change value;

[0128] Obtain a sample point in the core insulation temperature variation curve where the core insulation temperature is equal to the maximum insulation temperature and the core insulation temperature variation value is equal to the maximum insulation temperature variation value, to obtain at least one third sample point;

[0129] Acquire at least one fourth sample point corresponding to at least one third sample point from the winding insulation temperature variation curve;

[0130] taking a sample point in at least one fourth sample point where the winding insulation temperature is equal to the maximum insulation temperature and the winding insulation temperature change value is equal to the maximum insulation temperature change value as a critical point;

[0131] Determine the maximum winding heat flow rate corresponding to the critical point;

[0132] Based on the maximum winding heat flow rate, determine the current carrying capacity.

[0133] In the embodiment of the present application, the critical point is related to the heat resistance level of the insulating material in the transformer. The maximum insulation temperature and the maximum insulation temperature change value corresponding to different heat resistance levels, and the mapping relationship between the heat resistance level and the maximum insulation temperature and the maximum insulation temperature change value can be preset according to the actual test results. In order to ensure the safety of the dry-type transformer during operation, the core insulation temperature and the winding insulation temperature of the dry-type transformer must not exceed the maximum insulation temperature and the maximum insulation temperature change value.

[0134] Specifically, the controller first obtains the heat resistance grade corresponding to the insulation material in the transformer. The heat resistance grade corresponding to the insulation material is the factory parameter of the transformer and is stored in the database. The controller can directly obtain it from the database. Based on the heat resistance grade, the maximum insulation temperature and the maximum insulation temperature change value of the transformer can be determined.

[0135] Then, the controller obtains a sample point where the core insulation temperature is equal to the maximum insulation temperature and the core insulation temperature change value is equal to the maximum insulation temperature change value from the core insulation temperature change curve to obtain at least one third sample point. The core insulation temperature change value of each sample point in the core insulation temperature change curve can be represented by the differential of the core insulation temperature corresponding to the sample point.

[0136] Further, the controller will obtain at least one fourth sample point corresponding to at least one third sample point from the winding insulation temperature change curve according to at least one moment corresponding to at least one third sample point. The sample point in at least one fourth sample point where the winding insulation temperature is equal to the maximum insulation temperature and the winding insulation temperature change value is equal to the maximum insulation temperature change value is taken as a critical point. The winding insulation temperature change value of each sample point in the winding insulation temperature change curve can be represented by the differential of the winding insulation temperature corresponding to the sample point. It can be understood that there may be multiple sample points in at least one fourth sample point where the winding insulation temperature is equal to the maximum insulation temperature and the winding insulation temperature change value is equal to the maximum insulation temperature change value, and the controller will take the sample point with the smallest corresponding moment among the multiple sample points as the critical point.

[0137] Further, the controller determines the maximum winding heat flow rate according to the winding insulation temperature corresponding to the critical point. The maximum winding heating power corresponding to the critical point is determined according to the maximum winding heat flow rate. The maximum winding loss power corresponding to the critical point is determined according to the maximum winding heating power corresponding to the critical point, and the current carrying capacity of the transformer at the critical point is determined according to the maximum winding loss power corresponding to the critical point.

[0138] Therefore, by determining the sample points in the core insulation temperature change curve where the core insulation temperature is equal to the maximum insulation temperature and the core insulation temperature change value is equal to the maximum insulation temperature change value, and the sample points in the winding insulation temperature change curve where the winding insulation temperature is equal to the maximum insulation temperature and the winding insulation temperature change value is equal to the maximum insulation temperature change value, the critical point can be obtained. According to the maximum winding heat flow rate corresponding to the critical point, the current carrying capacity of the transformer at the critical point can be determined, and the current carrying capacity takes into account the core insulation temperature change and the winding insulation temperature change, thereby improving the accuracy of the current carrying capacity calculation.

[0139] It can be seen that in the embodiment of the present application, the core insulation temperature is obtained by the first temperature sensor deployed on the surface of the core of the transformer, the winding current and operating power are obtained by the electrical data collector connected to the winding, the winding insulation temperature is obtained by the second temperature sensor deployed on the surface of the winding, and the ambient temperature is obtained by the third temperature sensor deployed on the surface of the transformer, so as to obtain the operating data and temperature data of the transformer. Then, based on the temperature data, the heat exchange data of the transformer is determined, and based on the operating data, the heat source data of the transformer is determined. Further, based on the heat exchange data and the heat source data, the insulation temperature change curve is determined. Finally, based on the insulation temperature change curve, the current carrying capacity of the transformer is determined. Therefore, in combination with the operating data and temperature data of the transformer, the transformer is subjected to heat exchange calculation and heat source data calculation, and the insulation temperature change curve of the transformer under the current operating data and temperature data can be deduced, and based on the insulation temperature change curve, the current carrying capacity of the transformer is determined, and the current carrying capacity corresponds to the operating data and temperature data of the transformer, thereby improving the accuracy of the current carrying capacity calculation.

[0140] See also Figure 3 , Figure 3 A functional unit composition block diagram of a current carrying capacity determination device provided in an embodiment of the present application. The current carrying capacity determination device 300 is applied to a controller of a transformer, and the transformer also includes an iron core and a winding, a first temperature sensor is deployed on the surface of the iron core, a second temperature sensor is deployed on the surface of the winding, and the winding is connected to an electrical data collector; the electrical data collector, the first temperature sensor, and the second temperature sensor are all connected to the controller in communication; a third temperature sensor is deployed on the surface of the transformer, and the third temperature sensor is connected to the controller in communication; the current carrying capacity determination device 300 includes an acquisition unit 301 and a processing unit 302:

[0141] The acquisition unit 301 is used to acquire the operation data and temperature data of the transformer; wherein the operation data includes the winding current and the operation power, and the winding current and the operation power are collected by the electrical data collector; the temperature data includes: the core insulation temperature, the winding insulation temperature and the ambient temperature, and the core insulation temperature is collected by the first temperature sensor, the winding insulation temperature is collected by the second temperature sensor, and the ambient temperature is collected by the third temperature sensor;

[0142] The processing unit 302 is used to determine heat exchange data based on the temperature data; the heat exchange data includes a core heat flow rate and a winding heat flow rate;

[0143] Based on the operation data, heat source data is determined; the heat source data includes core heating power and winding heating power;

[0144] Based on the heat exchange data and the heat source data, an insulation temperature variation curve is determined; the insulation temperature variation curve includes an iron core insulation temperature variation curve and a winding insulation temperature variation curve;

[0145] Determine the current carrying capacity of the transformer based on the insulation temperature variation curve.

[0146] In a possible embodiment, in determining the heat exchange data based on the temperature data, the processing unit 302 is specifically configured to:

[0147] Obtain the transformer type, core thickness, core heat dissipation area, winding thickness, and winding heat dissipation area of ​​the transformer;

[0148] Based on the temperature data, determine the heat exchange efficiency coefficient corresponding to the transformer type;

[0149] Determine the core heat flow rate based on the heat exchange efficiency coefficient, core heat dissipation area, core thickness, core insulation temperature and ambient temperature;

[0150] The winding heat flow rate is determined based on the heat exchange efficiency coefficient, the winding heat dissipation area, the winding thickness, the winding insulation temperature and the ambient temperature.

[0151] In a possible embodiment, in determining the heat source data based on the operation data, the processing unit 302 is specifically configured to:

[0152] Acquire a plurality of first component materials and a plurality of first masses corresponding to the iron core, and a plurality of second component materials and a plurality of second masses corresponding to the windings, wherein the plurality of first component materials correspond one-to-one to the plurality of first masses, and the plurality of second component materials correspond one-to-one to the plurality of second masses;

[0153] determining a heat capacity of each of the plurality of first component materials to obtain a plurality of first heat capacities;

[0154] determining a ratio of each first mass in the plurality of first masses to a total mass of the plurality of first masses, to obtain a plurality of first ratios;

[0155] determining a first effective heat capacity of the core based on the plurality of first heat capacities and the plurality of first ratios;

[0156] Determine the no-load power of the transformer based on the operating power, and use the no-load power as the core loss power;

[0157] Determining the core heating power based on the first effective heat capacity and the core loss power;

[0158] determining a heat capacity of each second component material in the plurality of second component materials to obtain a plurality of second heat capacities;

[0159] determining a ratio of each second mass in the plurality of second masses to the total mass of the plurality of second masses, to obtain a plurality of second ratios;

[0160] determining a second effective thermal capacity of the winding based on the plurality of second thermal capacities and the plurality of second ratios;

[0161] Based on the winding current, determine the winding power loss;

[0162] The winding heating power is determined based on the second effective heat capacity and the winding loss power.

[0163] In a possible embodiment, in determining the winding power loss based on the winding current, the processing unit 302 is specifically configured to:

[0164] Obtain the resistance value, resistance temperature coefficient and factory winding insulation temperature corresponding to the winding; the resistance temperature coefficient indicates the ratio of the change in the winding insulation temperature to the winding insulation temperature when the winding insulation temperature increases by one unit temperature;

[0165] The winding power loss is determined by the following formula:

[0166] P Cu =I 2 R Cu [1+TCR(T Cu0 -T Cu )]

[0167] Among them, P Cu represents the winding power loss, I represents the winding current, R Cu represents the resistance value, TCR represents the temperature coefficient of resistance, T Cu0 Indicates the factory winding insulation temperature, T Cu Indicates the winding insulation temperature.

[0168] In a possible embodiment, in determining the insulation temperature variation curve based on the heat exchange data and the heat source data, the processing unit 302 is specifically configured to:

[0169] Obtain the temperature change limit value of the transformer;

[0170] Based on the heat flow rate of the iron core and the heating power of the iron core, a first heat balance relationship is established; based on the first heat balance relationship, a temperature change relationship of the iron core insulation is determined;

[0171] Based on the temperature change limit value and the relationship between the core insulation temperature change, the core insulation temperature is deduced to obtain multiple expected core insulation temperatures;

[0172] Performing curve fitting on multiple expected core insulation temperatures to obtain a core insulation temperature variation curve; establishing a second heat balance relationship based on the winding heat flow rate and the winding heating power;

[0173] Based on the second heat balance relationship, determining a winding insulation temperature variation relationship;

[0174] Based on the temperature change limit value and the relationship between the winding insulation temperature change, the winding insulation temperature is deduced to obtain multiple expected winding insulation temperatures;

[0175] Curve fitting is performed on multiple expected winding insulation temperatures to obtain a winding insulation temperature variation curve.

[0176] In a possible embodiment, when the current carrying capacity of the transformer includes the current carrying capacity corresponding to the thermal balance point, in determining the current carrying capacity of the transformer based on the insulation temperature change curve, the processing unit 302 is specifically configured to:

[0177] Acquire a plurality of first sample points and a plurality of first moments with a slope of 0 in the core insulation temperature variation curve; the plurality of first sample points correspond to the plurality of first moments one by one;

[0178] According to the multiple first moments, obtaining multiple second sample points from the winding insulation temperature variation curve;

[0179] Determine the slopes of a plurality of second sample points in the winding insulation temperature variation curve, and take the second sample point with a slope of 0 as a thermal equilibrium point;

[0180] Get the thermal equilibrium point limit value;

[0181] Based on the thermal balance point limit value, determine the maximum winding heating power corresponding to the thermal balance point;

[0182] Determine the current carrying capacity based on the maximum winding heating power.

[0183] In a possible embodiment, when the current carrying capacity of the transformer includes the current carrying capacity corresponding to the critical point, the processing unit 302 is specifically used to determine the current carrying capacity of the transformer based on the insulation temperature change curve:

[0184] Get the thermal resistance grade of the insulation material in the transformer;

[0185] Based on the heat resistance grade, determine the maximum insulation temperature and the maximum insulation temperature change value;

[0186] Obtain a sample point in the core insulation temperature variation curve where the core insulation temperature is equal to the maximum insulation temperature and the core insulation temperature variation value is equal to the maximum insulation temperature variation value, to obtain at least one third sample point;

[0187] Acquire at least one fourth sample point corresponding to at least one third sample point from the winding insulation temperature variation curve;

[0188] taking a sample point in at least one fourth sample point where the winding insulation temperature is equal to the maximum insulation temperature and the winding insulation temperature change value is equal to the maximum insulation temperature change value as a critical point;

[0189] Determine the maximum winding heat flow rate corresponding to the critical point;

[0190] Based on the maximum winding heat flow rate, determine the current carrying capacity.

[0191] See also Figure 4 , Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 4 As shown, the electronic device 400 includes a transceiver 401, a processor 402 and a memory 403. They are connected via a bus 404. The memory 403 is used to store computer programs and data, and can transmit the data stored in the memory 403 to the processor 402. The electronic device 400 can be the current carrying capacity determination device 300. The electronic device 400 can also be a controller of any of the above embodiments.

[0192] The processor 402 is used to read the computer program in the memory 403 and perform the following operations:

[0193] Obtain transformer operation data and temperature data;

[0194] Based on the temperature data, heat exchange data is determined; the heat exchange data includes the heat flow rate of the core and the heat flow rate of the winding;

[0195] Based on the operation data, determine the heat source data;

[0196] Determine the insulation temperature variation curve based on the heat exchange data and heat source data;

[0197] Determine the current carrying capacity of the transformer based on the insulation temperature variation curve.

[0198] The above mainly introduces the scheme of the embodiment of the present application from the perspective of the execution process on the method side. It is understandable that, in order to realize the above functions, the electronic device includes a hardware structure and / or software module corresponding to the execution of each function. It should be easily appreciated by those skilled in the art that, in combination with the units and algorithm steps of each example described in the embodiments provided herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present application.

[0199] An embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. The computer program is executed by a processor to implement part or all of the steps of any one of the methods described in the above method embodiments.

[0200] An embodiment of the present application also provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program, and the computer program is operable to cause a computer to execute part or all of the steps of any one of the methods recorded in the above method embodiments.

[0201] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present application.

[0202] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0203] In the several embodiments provided in the present application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, such as the division of the units, which is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the device or unit can be electrical or other forms.

[0204] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0205] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of a software program module.

[0206] If the integrated unit is implemented in the form of a software program module and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a memory, including a number of instructions to enable a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned memory includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or CD-ROM and other media that can store program codes.

[0207] A person skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable memory, and the memory can include: a flash drive, a read-only memory (English: Read-Only Memory, abbreviated as: ROM), a random access memory (English: Random Access Memory, abbreviated as: RAM), a magnetic disk or an optical disk, etc.

[0208] The embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for determining the current carrying capacity of a transformer, characterized in that: A controller applied to a transformer, the transformer further comprising an iron core and a winding, a first temperature sensor being disposed on the surface of the iron core, a second temperature sensor being disposed on the surface of the winding, and the winding being connected to an electrical data collector; The electrical data collector, the first temperature sensor and the second temperature sensor are all connected to the controller for communication; A third temperature sensor is disposed on the surface of the transformer, and the third temperature sensor is communicatively connected with the controller; the method comprises: Acquire the operating data and temperature data of the transformer; wherein the operating data includes winding current and operating power, and the winding current and the operating power are both collected by the electrical data collector; the temperature data includes: core insulation temperature, winding insulation temperature and ambient temperature, the core insulation temperature is collected by the first temperature sensor, the winding insulation temperature is collected by the second temperature sensor, and the ambient temperature is collected by the third temperature sensor; Based on the temperature data, heat exchange data is determined; the heat exchange data includes a core heat flow rate and a winding heat flow rate; Based on the operation data, heat source data is determined; the heat source data includes core heating power and winding heating power; Based on the heat exchange data and the heat source data, determining an insulation temperature change curve; the insulation temperature change curve includes an iron core insulation temperature change curve and a winding insulation temperature change curve; Based on the insulation temperature variation curve, the current carrying capacity of the transformer is determined.

2. The method according to claim 1, characterized in that The step of determining heat exchange data based on the temperature data comprises: Obtaining the transformer type, core thickness, core heat dissipation area, winding thickness, and winding heat dissipation area of ​​the transformer; Based on the temperature data, determining a heat exchange efficiency coefficient corresponding to the transformer type; Determining the core heat flow rate based on the heat exchange efficiency coefficient, the core heat dissipation area, the core thickness, the core insulation temperature and the ambient temperature; The winding heat flow rate is determined based on the heat exchange efficiency coefficient, the winding heat dissipation area, the winding thickness, the winding insulation temperature and the ambient temperature.

3. The method according to claim 1 or 2, characterized in that: The step of determining heat source data based on the operation data comprises: Acquire a plurality of first component materials and a plurality of first masses corresponding to the iron core, and a plurality of second component materials and a plurality of second masses corresponding to the winding, wherein the plurality of first component materials correspond to the plurality of first masses one-to-one, and the plurality of second component materials correspond to the plurality of second masses one-to-one; determining the heat capacity of each of the plurality of first component materials to obtain a plurality of first heat capacities; determining a ratio of each first mass in the plurality of first masses to a total mass of the plurality of first masses, to obtain a plurality of first ratios; determining a first effective heat capacity of the core based on the plurality of first heat capacities and the plurality of first ratios; Determine the no-load power of the transformer according to the operating power, and use the no-load power as the core loss power; Determining the core heating power based on the first effective heat capacity and the core loss power; determining a heat capacity of each of the plurality of second component materials to obtain a plurality of second heat capacities; determining a ratio of each second mass in the plurality of second masses to a total mass of the plurality of second masses to obtain a plurality of second ratios; determining a second effective thermal capacity of the winding based on the plurality of second thermal capacities and the plurality of second ratios; Based on the winding current, determining the winding power loss; The winding heating power is determined based on the second effective heat capacity and the winding loss power.

4. The method according to claim 3, characterized in that The step of determining the winding power loss based on the winding current comprises: Obtaining the resistance value, resistance temperature coefficient and factory winding insulation temperature corresponding to the winding; the resistance temperature coefficient represents the ratio of the winding insulation temperature change to the winding insulation temperature when the winding insulation temperature increases by one unit temperature; The winding power loss is determined by the following formula: P Cu =I 2 R Cu [1+TCR(T Cu0 -T Cu )] Among them, P Cu represents the winding power loss, I represents the winding current, R Cu represents the resistance value, TCR represents the temperature coefficient of resistance, T Cu0 Indicates the factory winding insulation temperature, T Cu Indicates the winding insulation temperature.

5. The method according to claim 1 or 2, characterized in that: The step of determining the insulation temperature variation curve based on the heat exchange data and the heat source data comprises: Obtaining a temperature change limit value of the transformer; Based on the core heat flow rate and the core heating power, a first heat balance relationship is established; based on the first heat balance relationship, a core insulation temperature change relationship is determined; Based on the temperature change limit value and the core insulation temperature change relationship, the core insulation temperature is deduced to obtain a plurality of expected core insulation temperatures; Performing curve fitting on the multiple expected core insulation temperatures to obtain the core insulation temperature variation curve; establishing a second heat balance relationship based on the winding heat flow rate and the winding heating power; Based on the second heat balance relationship, determining a winding insulation temperature change relationship; Based on the temperature change limit value and the winding insulation temperature change relationship, the winding insulation temperature is deduced to obtain a plurality of expected winding insulation temperatures; Curve fitting is performed on the multiple expected winding insulation temperatures to obtain the winding insulation temperature variation curve.

6. The method according to claim 1 or 2, characterized in that: When the current carrying capacity of the transformer includes the current carrying capacity corresponding to the thermal balance point, determining the current carrying capacity of the transformer based on the insulation temperature change curve includes: Acquire a plurality of first sample points and a plurality of first moments with a slope of 0 in the core insulation temperature change curve; the plurality of first sample points correspond one to one with the plurality of first moments; According to the multiple first moments, obtaining multiple second sample points from the winding insulation temperature variation curve; Determine the slopes of the plurality of second sample points in the winding insulation temperature variation curve, and use the second sample point with a slope of 0 as the thermal equilibrium point; Get the thermal equilibrium point limit value; Based on the thermal balance point limit value, determining the maximum winding heating power corresponding to the thermal balance point; The current carrying capacity is determined according to the maximum winding heating power.

7. The method according to claim 1 or 2, characterized in that: When the current carrying capacity of the transformer includes the current carrying capacity corresponding to the critical point, determining the current carrying capacity of the transformer based on the insulation temperature change curve includes: Obtaining the heat resistance grade of the insulating material in the transformer; Based on the heat resistance grade, determining a maximum insulation temperature and a maximum insulation temperature change value; Acquire a sample point in the core insulation temperature variation curve where the core insulation temperature is equal to the maximum insulation temperature and the core insulation temperature variation value is equal to the maximum insulation temperature variation value, to obtain at least one third sample point; Acquire at least one fourth sample point corresponding to the at least one third sample point from the winding insulation temperature variation curve; The sample point in the at least one fourth sample point where the winding insulation temperature is equal to the maximum insulation temperature and the winding insulation temperature change value is equal to the maximum insulation temperature change value is used as the critical point; Determining a maximum winding heat flow rate corresponding to the critical point; The current carrying capacity is determined based on the maximum winding heat flow rate.

8. A current carrying capacity determination device, characterized in that: A controller applied to a transformer, the transformer further comprising an iron core and a winding, a first temperature sensor being disposed on the surface of the iron core, a second temperature sensor being disposed on the surface of the winding, and the winding being connected to an electrical data collector; The electrical data collector, the first temperature sensor and the second temperature sensor are all connected to the controller for communication; A third temperature sensor is disposed on the surface of the transformer, and the third temperature sensor is communicatively connected with the controller; the device comprises: an acquisition unit, configured to acquire operation data and temperature data of the transformer; wherein the operation data includes winding current and operation power, and both the winding current and the operation power are acquired through the electrical data collector; the temperature data includes: core insulation temperature, winding insulation temperature and ambient temperature, and the core insulation temperature is acquired through the first temperature sensor, the winding insulation temperature is acquired through the second temperature sensor, and the ambient temperature is acquired through the third temperature sensor; A processing unit, configured to determine heat exchange data based on the temperature data; the heat exchange data includes a core heat flow rate and a winding heat flow rate; Based on the operation data, heat source data is determined; the heat source data includes core heating power and winding heating power; Based on the heat exchange data and the heat source data, determining an insulation temperature change curve; the insulation temperature change curve includes an iron core insulation temperature change curve and a winding insulation temperature change curve; Based on the insulation temperature variation curve, the current carrying capacity of the transformer is determined.

9. An electronic device, characterized in that: include: A processor and a memory, wherein the processor is connected to the memory, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device executes the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method according to any one of claims 1 to 7.

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