Hot-spot temperature rise determination method and high-overload transformer

Abstract

The invention discloses a hot-spot temperature rise determination method and a high-overload transformer, relates to the technical field of power transformer temperature rise, and aims to at least solve the problem that the limit value of hot-spot temperature rise of the high-overload transformer cannot be accurately determined due to the fact that dynamic changes of overload duration and amplitude are not fully considered. The method comprises the steps that the method is applied to a high-overload transformer, and multiple load rates of the high-overload transformer in the operation process of a preset period are determined; the operation process represents load changes borne by the high-overload transformer in different time periods or under different working conditions in a preset period; dispersing the operation process into a plurality of operation stages according to the size range of the plurality of load rates; determining a hot-spot temperature rise change relationship between hot-spot temperature rise and time in the corresponding load rate range in each operation stage; the hot-spot temperature rise change relations of all the operation stages are combined, and a target hot-spot temperature rise curve is obtained; and determining a hot-spot temperature rise limit value of the high-overload transformer according to the target hot-spot temperature rise curve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer temperature detection, and particularly relates to a hot-spot temperature rise determination method and a high overload transformer. BACKGROUND

[0002] The high overload dry-type transformer is widely used in the power grid system in periodic heavy load scenarios, such as urban power peak, rail transit or data center and the like. Under the high overload operation condition, the calculation of the temperature rise becomes the core to ensure the safe and reliable operation of the transformer. The hot-spot temperature rise not only directly affects the service life of the insulation system, but also determines whether the transformer can stably withstand the short-time or periodic load impact within the limited temperature range. It is found through research that in the related technology, most of the steady-state temperature rise is taken as the benchmark, and the influence of different load rates in the operation process is ignored, so that the hot-spot temperature rise at any moment in each stage of the operation process cannot be accurately determined. Moreover, the dynamic changes of the overload duration and amplitude are not fully considered, which causes the hot-spot temperature to exceed the limit value, thereby aggravating the insulation aging or even breakdown. SUMMARY

[0003] The present application provides a hot-spot temperature rise determination method and a high overload transformer to at least solve the problem that the dynamic changes of the overload duration and amplitude are not fully considered, which leads to the inability to accurately determine the limit value of the hot-spot temperature rise of the high overload transformer. The technical scheme of the present application is as follows:

[0004] According to a first aspect of the embodiment of the present application, a hot-spot temperature rise determination method is provided, which is applied to a high overload transformer, determines a plurality of load rates in the operation process of the high overload transformer in a preset period, and the operation process represents the load change of the high overload transformer in different time periods or working conditions in the preset period. The operation process is discretized into a plurality of operation stages according to the size range of the plurality of load rates. One operation stage corresponds to one load rate range. The hot-spot temperature rise change relationship between the hot-spot temperature rise and the time in the corresponding load rate range of each operation stage is determined. The hot-spot temperature rise change relationships of the operation stages are combined to obtain a target hot-spot temperature rise curve. The hot-spot temperature rise limit value of the high overload transformer is determined according to the target hot-spot temperature rise curve. The hot-spot temperature rise limit value includes a minimum temperature rise limit value and a maximum temperature rise limit value.

[0005] In an implementation manner, the plurality of operation stages include a first operation stage, a second operation stage and a third operation stage. Discretizing the operation process into a plurality of operation stages according to the size range of the plurality of load rates includes: sorting according to the size range of the plurality of load rates. The operation process is discretized into a plurality of operation stages according to the relationship between each load rate and the operation duration corresponding to each load rate. The first load rate range in the first operation stage is lower than the second load rate range in the second operation stage, which is lower than the third load rate range in the third operation stage.

[0006] In this embodiment, the running process is discretized into multiple running stages according to multiple load rates, so that the influence of the load rate of each running stage on the hot-spot temperature rise can be more accurately and significantly determined.

[0007] In another implementation, the determination of the hot-spot temperature rise change relationship between the hot-spot temperature rise and time in the corresponding load rate range of each running stage includes: determining, according to the first load rate range, a first starting point temperature rise value, a first terminal temperature rise value, a first time constant, and a hot-spot temperature rise value at any time in the first stage, so as to determine a first hot-spot temperature rise change relationship of the first running stage; and determining, according to the second load rate range, a second starting point temperature rise value, a second terminal temperature rise value, a second time constant, and a hot-spot temperature rise value at any time in the second stage, so as to determine a second hot-spot temperature rise change relationship of the second running stage; and determining, according to the third load rate range, a third starting point temperature rise value, a third terminal temperature rise value, a third time constant, and a hot-spot temperature rise value at any time in the third stage, so as to determine a third hot-spot temperature rise change relationship of the third running stage.

[0008] In this embodiment, the starting point, terminal point, time constant, and temperature rise value at any time in the running stage are determined, so as to determine the hot-spot temperature rise change relationship between the hot-spot temperature rise and time, and more accurately determine the temperature rise change trend of the running stage in each load rate range.

[0009] In another implementation, the method further includes: obtaining the winding average temperature rise under rated load; solving the winding hot-spot temperature rise under rated load according to the winding average temperature rise under rated load and the preset hot-spot temperature coefficient, to obtain a rated load hot-spot temperature rise; and determining a rated time constant of the winding under rated load condition according to the rated load hot-spot temperature rise; the time constant represents a time node when the hot-spot temperature rise curve tends to be stable.

[0010] In this embodiment, the rated time constant is determined, so as to measure the response speed of the high-load transformer in the steady-state process.

[0011] In another implementation, the first load rate range includes a first start load rate and a first end load rate; the initial load rate represents a load rate when the no-load loss occurs; the first end load rate represents a target load rate corresponding to the first operation stage; and the first hot spot temperature rise change relationship of the first operation stage is determined according to the first load rate range, including: solving a first start non-linear variable according to the first start load rate and a preset empirical constant; solving a first end non-linear variable according to the first end load rate and the preset empirical constant; determining the first start temperature rise value according to the rated load hot spot temperature rise and the first start non-linear variable; determining the first end temperature rise value according to the rated load hot spot temperature rise and the first end non-linear variable; obtaining the first time constant according to the rated time constant, the first start non-linear variable and the first end non-linear variable; determining the hot spot temperature rise value at any time in the first stage according to the first start temperature rise value, the first end temperature rise value and the first time constant; and determining the first hot spot temperature rise change relationship according to the correlation among the first start temperature rise value, the first end temperature rise value, the first time constant and the hot spot temperature rise value at any time in the first stage.

[0012] In another implementation, the second load rate range includes a second start load rate and a second end load rate; the second start load rate is equal to the first end load rate of the first operation stage; the second end load rate represents a target load rate corresponding to the second operation stage; and the second hot spot temperature rise change relationship of the second operation stage is determined according to the second load rate range, including: solving a second start non-linear variable according to the second start load rate and a preset empirical constant; solving a second end non-linear variable according to the second end load rate and the preset empirical constant; determining the second start temperature rise value according to the rated load hot spot temperature rise and the second start non-linear variable; determining the second end temperature rise value according to the rated load hot spot temperature rise and the second end non-linear variable; obtaining the second time constant according to the rated time constant, the second start non-linear variable and the second end non-linear variable; determining the hot spot temperature rise value at any time in the second stage according to the second start temperature rise value, the second end temperature rise value and the second time constant; and determining the second hot spot temperature rise change relationship according to the correlation among the second start temperature rise value, the second end temperature rise value, the second time constant and the hot spot temperature rise value at any time in the second stage.

[0013] In another implementation, the third load rate range comprises a third starting load rate and a third ending load rate; the third starting load rate is equal to the second ending load rate of the second operation stage; the third ending load rate represents a target load rate corresponding to the third operation stage; and the third hot spot temperature rise change relationship of the third operation stage is determined according to the third load rate range, including: solving a third starting non-linear variable according to the third starting load rate and a preset empirical constant; solving a third ending non-linear variable according to the third ending load rate and the preset empirical constant; determining the third starting temperature rise value according to the rated load hot spot temperature rise and the third starting non-linear variable; determining the third ending temperature rise value according to the rated load hot spot temperature rise and the third ending non-linear variable; obtaining the third time constant according to the rated time constant, the third starting non-linear variable and the third ending non-linear variable; determining the hot spot temperature rise value at any time in the third stage according to the third starting temperature rise value, the third ending temperature rise value and the third time constant; and determining the third hot spot temperature rise change relationship according to the correlation among the third starting temperature rise value, the third ending temperature rise value, the third time constant and the hot spot temperature rise value at any time in the third stage.

[0014] In another implementation, the hot spot temperature rise change relationships of the operation stages are combined to obtain a target hot spot temperature rise curve, including: combining the first hot spot temperature rise change relationship, the second hot spot temperature rise change relationship and the third hot spot temperature rise change relationship to obtain the target hot spot temperature rise curve.

[0015] In this embodiment, the hot spot temperature rise range of the high load transformer in the entire operation process is determined by combining the stages.

[0016] In another implementation, the hot spot temperature rise limit of the high load transformer is determined according to the target hot spot temperature rise curve, including: determining the starting temperature rise value of the target hot spot temperature rise curve as the minimum temperature rise limit; and determining the ending temperature rise value of the target hot spot temperature rise curve as the maximum temperature rise limit.

[0017] According to a second aspect of the embodiment of the present application, a high load transformer is provided, which comprises a core and a winding; the core is a magnetic conductive material, the magnetic permeability of the magnetic conductive material is higher than a preset magnetic permeability, and the loss of the magnetic conductive material is lower than a preset loss; the heat resistance grade of the winding is F grade or above, and the winding is a dry type ceramic insulation structure, and the hot spot temperature rise determination method in any one of the above-mentioned implementation manners of the first aspect is adopted.

[0018] According to a third aspect of the embodiment of the present application, a hot spot temperature rise determination system is provided, which is configured to perform the hot spot temperature rise determination method of the first aspect and any possible implementation manner thereof.

[0019] According to a fourth aspect of the embodiments of the present application, a hotspot temperature rise determination device is provided, which is configured to perform the hotspot temperature rise determination method according to the first aspect and any possible implementation manner thereof.

[0020] According to a fifth aspect of the embodiments of the present application, a computer readable storage medium is provided, and the computer readable storage medium stores instructions, when the instructions in the computer readable storage medium are executed by a processor of a hotspot temperature rise determination device, the hotspot temperature rise determination device is enabled to perform the hotspot temperature rise determination method according to the first aspect and any possible implementation manner thereof.

[0021] According to a sixth aspect of the embodiments of the present application, a computer program product is provided, and the computer program product comprises computer instructions, when the computer instructions are run on a hotspot temperature rise determination device, the hotspot temperature rise determination device performs the hotspot temperature rise determination method according to the first aspect and any possible implementation manner thereof.

[0022] The embodiments of the present application provide at least the following beneficial effects:

[0023] The multiple load rates generated by the high overload transformer under the influence of different working conditions are determined, and the multiple load rates are sorted according to the size range of the load rates, and the running process is discretized into multiple running stages, so that the influence of each different load rate on the hotspot temperature rise can be distinguished more accurately and significantly. According to the load rate range of each running stage, the hotspot temperature rise change relationship between the hotspot temperature rise and the time of each running stage is determined, so that the hotspot temperature rise change of different running stages is more accurately determined. The hotspot temperature rise change relationship of each running stage is combined and processed, so that the hotspot temperature rise change curve of the entire running process of the high overload transformer is accurately determined. According to the hotspot temperature rise change condition embodied by the hotspot temperature rise change curve, the hotspot temperature rise limit value of the high overload transformer can be more intuitively and accurately determined. Therefore, by using the above hotspot temperature rise determination method, the influence of different load rates in different running stages on the hotspot temperature rise is fully considered, and the dynamic changes of the overload duration and the hotspot temperature rise amplitude are fully considered, so that the limit value of the hotspot temperature rise of the high overload transformer is more accurately determined.

[0024] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] The drawings incorporated into the specification and forming a part thereof, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application, and do not constitute an undue limitation on the present application.

[0026] Figure 1is a schematic diagram of a hotspot temperature rise determination system according to an exemplary embodiment;

[0027] Figure 2 is a flowchart of a hotspot temperature rise determination method according to an exemplary embodiment Figure 1 ;

[0028] Figure 3 is a flowchart of a hotspot temperature rise determination method according to an exemplary embodiment Figure 2 ;

[0029] Figure 4 is a schematic diagram of a hotspot temperature rise determination device according to an exemplary embodiment. DETAILED DESCRIPTION

[0030] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0032] Before the hotspot temperature rise determination method provided by the embodiments of the present application is described in detail, the application scenarios involved in the embodiments of the present application will be briefly introduced.

[0033] High overload dry-type transformers are widely used in periodic heavy load scenarios in power grid systems, such as urban peak electricity consumption, rail transit or data centers, etc. Under high overload operating conditions, temperature rise calculation is the core to ensure the safe and reliable operation of the transformer. The hotspot temperature rise represents the difference between the temperature of the hottest point in the transformer during operation and the temperature of the surrounding environment, and generally, the hotspot position occurs on the winding of the transformer. The hotspot temperature rise not only directly affects the service life of the insulation system, but also determines whether the transformer can stably withstand short-time or periodic load impact within the limited temperature range.

[0034] It is found through research that most of the baselines for steady-state temperature rise ignore the influence of different load rates in the running process, so that the hotspot temperature rise at any time in each stage of the running process cannot be accurately determined. Moreover, the dynamic changes of the duration and amplitude of overload are not fully considered, which causes the hotspot temperature to exceed the limit value, thereby accelerating the insulation aging and even breakdown.

[0035] In addition, the existing high overload transformer does not fully consider the use of environmentally friendly insulating medium or high permeability and low loss material, which is difficult to meet the current trend of green and low-carbon development. In order to avoid risks, high margin design strategies are often used, which leads to waste of material and space resources, increases the manufacturing and operating costs, and does not have environmental advantages.

[0036] In view of the above problems, the present application provides a hotspot temperature rise determination method, determines multiple load rates generated by a high overload transformer under the influence of different working conditions, sorts the load rates according to their size ranges, discretizes the running process into multiple running stages, and fully considers the influence of each load rate on the hotspot temperature rise in each running stage. According to the load rate range of each running stage, the hotspot temperature rise change relationship between the hotspot temperature rise and the time of each running stage is determined, so as to more accurately determine the hotspot temperature rise change of different running stages. The hotspot temperature rise change relationship of each running stage is combined and processed, so as to accurately determine the hotspot temperature rise change curve of the entire running process of the high overload transformer. According to the hotspot temperature rise change reflected by the hotspot temperature rise change curve, the hotspot temperature rise limit value of the high overload transformer can be more intuitively and accurately determined.

[0037] Secondly, the implementation architecture related to the present application will be briefly introduced below.

[0038] Figure 1 is a schematic diagram of a hotspot temperature rise determination system provided by the present application. As shown in Figure 1 , the hotspot temperature rise determination system comprises a running stage determination module 101, a hotspot temperature rise relationship determination module 102 and a hotspot temperature rise limit value determination module 103.

[0039] The running stage determination module 101, the hotspot temperature rise relationship determination module 102 and the hotspot temperature rise limit value determination module 103 are in communication connection.

[0040] The running stage determination module 101 is configured to determine multiple load rates of a high overload transformer in a running process of a preset period; and discretize the running process into multiple running stages according to the size range of the multiple load rates.

[0041] The hotspot temperature rise relationship determination module 102 is configured to determine the hotspot temperature rise change relationship between the hotspot temperature rise and time under the corresponding load rate range in each operation stage; and combine the hotspot temperature rise change relationships of the operation stages to obtain a target hotspot temperature rise curve.

[0042] The hotspot temperature rise limit value determination module 103 is configured to determine the hotspot temperature rise limit value of the high overload transformer according to the target hotspot temperature rise curve.

[0043] For ease of understanding, the hotspot temperature rise determination method provided in the present application is specifically introduced below in combination with the drawings.

[0044] Figure 2 is a flowchart of a hotspot temperature rise determination method according to an exemplary embodiment Figure 1 As shown in the figure, the hotspot temperature rise determination method includes the following steps. Figure 2

[0045] S21, determining a plurality of load rates of the high overload transformer in an operation process in a preset period.

[0046] The operation process represents the load change of the high overload transformer in different time periods or working conditions in the preset period.

[0047] The different time periods can include a plurality of load rates caused by load differences such as diurnal load differences and seasonal influence differences.

[0048] The different working conditions can include a plurality of loads caused by continuous rated load, short-time overload, or high-temperature environment influence, etc.

[0049] S22, discretizing the operation process into a plurality of operation stages according to the size range of the plurality of load rates.

[0050] One operation stage corresponds to one load rate range.

[0051] In an embodiment, the plurality of operation stages includes a first operation stage, a second operation stage, and a third operation stage.

[0052] The plurality of load rates are sorted according to the size range.

[0053] The operation process is discretized into a plurality of operation stages according to the relationship between each load rate and the operation duration corresponding to each load rate.

[0054] The first load rate range in the first operation stage is lower than the second load rate range in the second operation stage, which is lower than the third load rate range in the third operation stage.

[0055] S23, determining the hotspot temperature rise change relationship between the hotspot temperature rise and time under the corresponding load rate range in each operation stage.​

[0056] The determination of the hotspot temperature rise change relationship of each operating stage is a conversion from the load rate change relationship to the hotspot temperature rise change relationship, so as to more accurately determine the influence of the load rate on the hotspot temperature rise under different working conditions.

[0057] In one embodiment, first, according to the first load rate range, a first starting temperature rise value, a first ending temperature rise value, a first time constant, and a hotspot temperature rise value at any time in the first stage are determined, so as to determine a first hotspot temperature rise change relationship of the first operating stage.

[0058] Secondly, according to the second load rate range, a second starting temperature rise value, a second ending temperature rise value, a second time constant, and a hotspot temperature rise value at any time in the second stage are determined, so as to determine a second hotspot temperature rise change relationship of the second operating stage.

[0059] Thirdly, according to the third load rate range, a third starting temperature rise value, a third ending temperature rise value, a third time constant, and a hotspot temperature rise value at any time in the third stage are determined, so as to determine a third hotspot temperature rise change relationship of the third operating stage.

[0060] S24, the hotspot temperature rise change relationships of each operating stage are combined to obtain a target hotspot temperature rise curve.

[0061] In one embodiment, the first hotspot temperature rise change relationship, the second hotspot temperature rise change relationship, and the third hotspot temperature rise change relationship are combined to obtain the target hotspot temperature rise curve.

[0062] In this embodiment, the first ending temperature rise value of the first hotspot temperature rise change relationship is equal to the second starting temperature rise value of the second hotspot temperature rise change relationship. The second ending temperature rise value of the second hotspot temperature rise change relationship is equal to the third starting temperature rise value of the third hotspot temperature rise change relationship.

[0063] If the data deviates during the combination process, the data of the solving process is adaptively adjusted.

[0064] S25, according to the target hotspot temperature rise curve, a hotspot temperature rise limit value of the high overload transformer is determined.

[0065] In one embodiment, the starting temperature rise value of the target hotspot temperature rise curve is determined as the minimum temperature rise limit value, and the ending temperature rise value of the target hotspot temperature rise curve is determined as the maximum temperature rise limit value.

[0066] Further, in order to determine the target hotspot temperature rise curve, the third operating stage hotspot temperature rise value is determined as the highest hotspot temperature rise value θ 3t = θ max, the highest hot-spot temperature rise limit of the transformer under over-load is determined.

[0067]

[0068] wherein θ max is the highest hot-spot temperature rise value; Δθ Wr is the winding average temperature rise under rated load; is the third end-point non-linear variable; is the third start-point non-linear variable; t3 is any time point in the third stage; τ3 is the third time constant, θ a is the ambient temperature.

[0069] It can be understood that the hot-spot temperature rise is the difference between the hot-spot temperature and the ambient temperature, and the highest hot-spot temperature rise limit of the transformer under over-load is determined by determining the sum of the hot-spot temperature rise value and the ambient temperature.

[0070] In an embodiment, as Figure 3 the above step S23 is implemented by the following steps S231 to S234.

[0071] S231, before determining the hot-spot temperature rise transformation relationship of each operating stage, the rated time constant is first determined.

[0072] The time constant represents the time node when the hot-spot temperature rise curve tends to be stable.

[0073] Specifically, the rated time constant is determined by the following formulas (3) to (5).

[0074] First, the winding average temperature rise under rated load is obtained.

[0075] Second, according to the winding average temperature rise under rated load and the preset hot-spot temperature coefficient, the winding hot-spot temperature rise under rated load is solved to obtain the rated load hot-spot temperature rise. Specifically, as shown in the following formula (3).

[0076] Δθ HSr = Z x Δθ Wr (3).

[0077] wherein Δθ Wr is the winding average temperature rise under rated load; Δθ HSr is the temperature rise of the winding hot-spot to the environment under the considered load; Z is the preset hot-spot temperature coefficient.

[0078] Finally, according to the rated load hot-spot temperature rise, the rated time constant of the winding under rated load condition is determined. Specifically, as shown in the following formula (4).

[0079]

[0080] wherein τ R is the rated time constant; C is the effective thermal capacity of the winding; θ e is the effect of the core on the winding hot-spot temperature rise at no load; P r is the total winding loss at rated load and rated temperature rise.

[0081] And the effective thermal capacity of the winding is shown by the following formula (5).

[0082] C = 0.25 x weight of aluminum conductor + 0.408 x weight of insulation material and other winding insulation (5).

[0083] It can be understood that the highest hot-spot temperature limit of the winding obtained by taking the highest hot-spot temperature allowed by the heat resistance level of the winding insulation of the high overload transformer as the boundary condition for determining the hot-spot temperature rise ensures that the highest hot-spot temperature of the winding does not exceed the allowed value of the insulation heat resistance level, and guarantees the safe and stable operation of the high overload transformer.

[0084] S232, determining a first hot-spot temperature rise change relationship of the first operation stage.

[0085] In an embodiment, the first hot-spot temperature rise change relationship is determined by formula (6) to formula (10).

[0086] The first load rate range includes a first starting load rate and a first terminal load rate.

[0087] The initial load rate represents the load rate at no-load loss, and the first terminal load rate represents the target load rate corresponding to the first operation stage.

[0088] First, according to the first starting load rate and a preset empirical constant, a first starting nonlinear variable is solved.

[0089] Specifically, representing the nonlinear relationship between temperature rise and load change.

[0090] wherein I n is a given load rate; q is an empirical constant.

[0091] In this embodiment, the preset empirical constant is set to 1.6, and the given load rate I n is set to the first starting load rate.

[0092] Thus, the nonlinear relationship between temperature rise and load change is determined, and the first starting nonlinear variable

[0093] Second, according to the first terminal load rate and a preset empirical constant, a first terminal nonlinear variable is solved.

[0094] The preset experience constant is set as 1.6, and the load rate I is given n The first end point load rate is set.

[0095] The nonlinear relationship of the temperature rise with the load is determined, and the first end point nonlinear variable is obtained

[0096] Thirdly, the first start point temperature rise value is determined according to the rated load hot spot temperature rise and the first start point nonlinear variable. Specifically, as shown in the following formula (6).

[0097] In this embodiment, the preset hot spot temperature coefficient is 1.25.

[0098]

[0099] Where, Δθ 1i is the first start point temperature rise value; Δθ Wr is the winding average temperature rise under the rated load; is the first start point nonlinear variable.

[0100] Fourthly, the first end point temperature rise value is determined according to the rated load hot spot temperature rise and the first end point nonlinear variable. Specifically, as shown in the following formula (7).

[0101]

[0102] Where, Δθ 1u is the first end point temperature rise value; Δθ Wr is the winding average temperature rise under the rated load; is the first end point nonlinear variable.

[0103] Fifthly, the first time constant is obtained according to the rated time constant, the first start point nonlinear variable and the first end point nonlinear variable determined in the above step S231. Specifically, as shown in the following formula (8).

[0104]

[0105] Where, τ1 is the first time constant; τ R is the rated time constant; is the first start point nonlinear variable; is the first end point nonlinear variable.

[0106] Sixthly, the hot spot temperature rise value at any time in the first stage is determined according to the first start point temperature rise value, the first end point temperature rise value and the first time constant. Specifically, as shown in the following formula (9) and formula (10).

[0107]

[0108] Where, Δθ1t is the hotspot temperature rise value at any time point in the first stage; Δθ 1i is the first start temperature rise value; Δθ 1u is the first end temperature rise value; t1 is any time point in the first stage; τ1 is the first time constant;

[0109] In this embodiment, according to each variable obtained in the above process, the conversion result of formula (9) is obtained, as shown in formula (10).

[0110]

[0111] wherein, Δθ 1t is the hotspot temperature rise value at any time point in the first stage; Δθ Wr is the winding average temperature rise under rated load; is the first end non-linear variable; is the first start non-linear variable; t1 is any time point in the first stage; τ1 is the first time constant.

[0112] Seventh, according to the correlation between the first start temperature rise value, the first end temperature rise value, the first time constant and the hotspot temperature rise value at any time point in the first stage, the first hotspot temperature rise change relationship is determined.

[0113] It can be understood that the hotspot temperature rise starts to increase from the first start temperature rise value, and after the first time constant, the hotspot temperature rise tends to be stable, reaches the highest value of the first running stage, and finally reaches the second end temperature rise value.

[0114] S233, determining a second hotspot temperature rise change relationship of a second running stage.

[0115] In an embodiment, the first hotspot temperature rise change relationship is determined by formula (11) to formula (14).

[0116] The second load rate range includes a second start load rate and a second end load rate.

[0117] The second start load rate is equal to the first end load rate of the first running stage; and the second end load rate represents a target load rate corresponding to the second running stage.

[0118] First, according to the second start load rate and a preset empirical constant, a second start non-linear variable is solved.

[0119] In this embodiment, the preset empirical constant is set to 1.6, and the given load rate I n is set to the second start load rate.

[0120] Thus, the non-linear relationship of temperature rise with load is determined, and the second start non-linear variable is obtained

[0121] Second, according to the second endpoint load rate and a preset empirical constant, the second endpoint nonlinear variable is solved.

[0122] The preset empirical constant is set as 1.6, and the load rate I n is set as the second endpoint load rate.

[0123] In this way, the nonlinear relationship of temperature rise with load change is determined, and the second endpoint nonlinear variable

[0124] Third, according to the rated load hot spot temperature rise and the second starting point nonlinear variable, the second starting point temperature rise value is determined. Specifically, as shown in the following formula (11).

[0125] In this embodiment, the preset hot spot temperature coefficient is 1.25.

[0126]

[0127] Where, Δθ 2i is the second starting point temperature rise value; Δθ Wr is the winding average temperature rise under rated load; is the second starting point nonlinear variable.

[0128] Fourth, according to the rated load hot spot temperature rise and the second endpoint nonlinear variable, the second endpoint temperature rise value is determined. Specifically, as shown in the following formula (12).

[0129]

[0130] Where, Δθ 2u is the second endpoint temperature rise value; Δθ Wr is the winding average temperature rise under rated load; is the second endpoint nonlinear variable.

[0131] Fifth, the rated time constant determined by the above step S231, the second starting point nonlinear variable and the second endpoint nonlinear variable, the second time constant is obtained. Specifically, as shown in the following formula (13).

[0132]

[0133] Where, τ2 is the second time constant; τ R is the rated time constant; is the second starting point nonlinear variable; is the second endpoint nonlinear variable.

[0134] Sixth, determine the hot-spot temperature rise value at any time in the second stage according to the second initial temperature rise value, the second final temperature rise value and the second time constant. According to the formula (7) directly deduced in the above step S232, it is specifically shown in the following formula (14).

[0135]

[0136] wherein, Δθ 2t is the hot-spot temperature rise value at any time in the second stage; Δθ Wr is the winding average temperature rise under the rated load; is the second final nonlinear variable; is the second initial nonlinear variable; t2 is any time point in the second stage; τ2 is the second time constant.

[0137] Seventh, determine the second hot-spot temperature rise change relationship according to the correlation between the second initial temperature rise value, the second final temperature rise value, the second time constant and the hot-spot temperature rise value at any time in the second stage.

[0138] It can be understood that the hot-spot temperature rise starts to increase from the second initial temperature rise value, and after the second time constant, the hot-spot temperature rise tends to be stable, reaches the highest value of the second running stage, and finally reaches the second final temperature rise value.

[0139] S234, determine the third hot-spot temperature rise change relationship of the third running stage.

[0140] In an embodiment, the first hot-spot temperature rise change relationship is determined by the formula (15) to the formula (18).

[0141] wherein, the third load rate range includes a third initial load rate and a third final load rate.

[0142] The third initial load rate is equal to the second final load rate of the second running stage; the third final load rate represents the target load rate corresponding to the third running stage.

[0143] First, solve the third initial nonlinear variable according to the third initial load rate and a preset empirical constant.

[0144] In this embodiment, the preset empirical constant is set to 1.6, and the given load rate I n is set to the third initial load rate.

[0145] In this way, the nonlinear relationship between the temperature rise and the load is determined, and the third initial nonlinear variable

[0146] Second, solve the third final nonlinear variable according to the third final load rate and the preset empirical constant.

[0147] The preset experience constant is set as 1.6, and the load rate I is given n Set as the third end point load rate.

[0148] Determine the nonlinear relationship of temperature rise with load change, and obtain the third end point nonlinear variable

[0149] Thirdly, according to the rated load hot spot temperature rise and the third starting point nonlinear variable, the third starting point temperature rise value is determined. Specifically, as shown in the following formula (15).

[0150] In this embodiment, the preset hot spot temperature coefficient is 1.25.

[0151]

[0152] Where, Δθ 3i is the third starting point temperature rise value; Δθ Wr is the average temperature rise of the winding under rated load; is the third starting point nonlinear variable.

[0153] Fourthly, according to the rated load hot spot temperature rise and the third end point nonlinear variable, the third end point temperature rise value is determined. Specifically, as shown in the following formula (16).

[0154]

[0155] Where, Δθ 3u is the third end point temperature rise value; Δθ Wr is the average temperature rise of the winding under rated load; is the third end point nonlinear variable.

[0156] Fifthly, the rated time constant, the third starting point nonlinear variable and the third end point nonlinear variable determined by the above step S231 are obtained. Specifically, as shown in the following formula (17).

[0157]

[0158] Where, τ3 is the third time constant; τ R is the rated time constant; is the third starting point nonlinear variable; is the third end point nonlinear variable.

[0159] Sixthly, according to the third starting point temperature rise value, the third end point temperature rise value and the third time constant, the hot spot temperature rise value at any time in the third stage is determined. According to the formula (7) directly deduced in the above step 232, specifically as shown in the following formula (18).

[0160]

[0161] wherein, Δθ 3t is the hot-spot temperature rise at any time during the third phase; Δθ Wr is the average winding temperature rise under rated load; is the third end-point non-linear variable; is the third start-point non-linear variable; t3 is any time point during the third phase; τ3 is the third time constant.

[0162] Seventh, according to the correlation between the third start-point temperature rise value, the third end-point temperature rise value, the third time constant and the hot-spot temperature rise at any time during the third phase, the third hot-spot temperature rise change relationship is determined.

[0163] It can be understood that the hot-spot temperature rise starts to increase from the third start-point temperature rise value, and after the third time constant, the hot-spot temperature rise tends to be stable, reaches the highest value of the third operating phase, and finally reaches the third end-point temperature rise value.

[0164] The embodiment of the present application also provides a high overload transformer, which comprises a core and a winding.

[0165] The core is made of magnetic conductive material, the magnetic permeability of the magnetic conductive material is higher than a preset magnetic permeability, and the loss of the magnetic conductive material is lower than a preset loss.

[0166] The heat resistance grade of the winding is F grade or above, and the winding is a dry type ceramic insulation structure.

[0167] In an embodiment, the magnetic conductive material of the core includes but is not limited to amorphous alloy or 27M6 grade cold-rolled silicon steel sheet.

[0168] The winding insulation material can be selected from polyester imine enameled wire with a heat resistance grade of F grade or above, and full rubber insulation paper or ceramic coated conductor wire.

[0169] It can be understood that the temperature range of the high overload transformer during operation is higher than the temperature range when the load is rated, the winding with a heat resistance grade of F grade or above is selected, and the winding adopts a dry type ceramic insulation structure, wherein the micro-arc oxidation technology is a new technology based on hard anode oxidation technology, which can directly grow a ceramic film with high corrosion resistance, high wear resistance, high insulation, heat shock resistance and other excellent properties on the surface of metals such as aluminum, magnesium, titanium, zirconium and niobium. The insulation layer of the ceramic film winding conductor wire ensures the high overload and high temperature resistance characteristics of the winding. The stable operation of the high load transformer can be ensured.

[0170] The high overload transformer is configured to determine a plurality of load rates of the high overload transformer in a preset period of operation process; the operation process represents load changes of the high overload transformer in different time periods or working conditions in the preset period; the operation process is discretized into a plurality of operation stages according to the size range of the plurality of load rates; one operation stage corresponds to one load rate range; the hot spot temperature rise change relationship between the hot spot temperature rise and time in the corresponding load rate range in each operation stage is determined; the hot spot temperature rise change relationships of the operation stages are combined to obtain a target hot spot temperature rise curve; the hot spot temperature rise limit value of the high overload transformer is determined according to the target hot spot temperature rise curve; the hot spot temperature rise limit value includes a minimum temperature rise limit value and a maximum temperature rise limit value.

[0171] As an implementation manner, the plurality of operation stages include: a first operation stage, a second operation stage and a third operation stage.

[0172] The high overload transformer is specifically configured to sort according to the size range of the plurality of load rates; the operation process is discretized into a plurality of operation stages according to the relationship between each load rate and the operation time corresponding to each load rate; the first load rate range in the first operation stage is lower than the second load rate range in the second operation stage, which is lower than the third load rate range in the third operation stage.

[0173] As an implementation manner, the high overload transformer is specifically configured to determine the hot spot temperature rise change relationship between the hot spot temperature rise and time in the corresponding load rate range in each operation stage, including: determining a first starting temperature rise value, a first ending temperature rise value, a first time constant and a hot spot temperature rise value at any time in the first stage according to the first load rate range, so as to determine the first hot spot temperature rise change relationship of the first operation stage; and determining a second starting temperature rise value, a second ending temperature rise value, a second time constant and a hot spot temperature rise value at any time in the second stage according to the second load rate range, so as to determine the second hot spot temperature rise change relationship of the second operation stage; and determining a third starting temperature rise value, a third ending temperature rise value, a third time constant and a hot spot temperature rise value at any time in the third stage according to the third load rate range, so as to determine the third hot spot temperature rise change relationship of the third operation stage.

[0174] As an implementation manner, the high overload transformer is specifically configured to obtain the winding average temperature rise under the rated load; the winding hot spot temperature rise under the rated load is solved according to the winding average temperature rise under the rated load and the preset hot spot temperature coefficient, to obtain the rated load hot spot temperature rise; the rated time constant of the winding under the rated load condition is determined according to the rated load hot spot temperature rise; the time constant represents a time node when the hot spot temperature rise curve tends to be stable.

[0175] As an implementation manner, the high overload transformer is specifically configured to: the first load rate range includes a first starting load rate and a first terminal load rate; the initial load rate represents a load rate when the no-load loss is represented; the first terminal load rate represents a target load rate corresponding to the first running stage; according to the first load rate range, a first starting temperature rise value, a first terminal temperature rise value, a first time constant and a hotspot temperature rise value at any time in the first stage are determined, so as to determine the first hotspot temperature rise change relationship of the first running stage, which includes: according to the first starting load rate and a preset empirical constant, a first starting non-linear variable is solved; according to the first terminal load rate and the preset empirical constant, a first terminal non-linear variable is solved; according to the rated load hotspot temperature rise and the first starting non-linear variable, the first starting temperature rise value is determined; according to the rated load hotspot temperature rise and the first terminal non-linear variable, the first terminal temperature rise value is determined; according to the rated time constant, the first starting non-linear variable and the first terminal non-linear variable, the first time constant is obtained; according to the first starting temperature rise value, the first terminal temperature rise value and the first time constant, the hotspot temperature rise value at any time in the first stage is determined; according to the correlation relationship among the first starting temperature rise value, the first terminal temperature rise value, the first time constant and the hotspot temperature rise value at any time in the first stage, the first hotspot temperature rise change relationship is determined.

[0176] As an implementation manner, the high overload transformer is specifically configured to: the second load rate range includes a second starting load rate and a second terminal load rate; the second starting load rate is equal to the first terminal load rate of the first running stage; the second terminal load rate represents a target load rate corresponding to the second running stage; according to the second load rate range, a second starting temperature rise value, a second terminal temperature rise value, a second time constant and a hotspot temperature rise value at any time in the second stage are determined, so as to determine the second hotspot temperature rise change relationship of the second running stage, which includes: according to the second starting load rate and a preset empirical constant, a second starting non-linear variable is solved; according to the second terminal load rate and the preset empirical constant, a second terminal non-linear variable is solved; according to the rated load hotspot temperature rise and the second starting non-linear variable, the second starting temperature rise value is determined; according to the rated load hotspot temperature rise and the second terminal non-linear variable, the second terminal temperature rise value is determined; according to the rated time constant, the second starting non-linear variable and the second terminal non-linear variable, the second time constant is obtained; according to the second starting temperature rise value, the second terminal temperature rise value and the second time constant, the hotspot temperature rise value at any time in the second stage is determined; according to the correlation relationship among the second starting temperature rise value, the second terminal temperature rise value, the second time constant and the hotspot temperature rise value at any time in the second stage, the second hotspot temperature rise change relationship is determined.

[0177] As an implementation form, the high overload transformer is specifically configured to: the third load rate range comprises a third starting load rate and a third terminal load rate; the third starting load rate is equal to the second terminal load rate of the second operation stage; the third terminal load rate represents a target load rate corresponding to the third operation stage; and the third thermal point temperature rise change relationship of the third operation stage is determined according to the third load rate range, including: solving a third starting non-linear variable according to the third starting load rate and a preset empirical constant; solving a third terminal non-linear variable according to the third terminal load rate and the preset empirical constant; determining the third starting temperature rise value according to the rated load thermal point temperature rise and the third starting non-linear variable; determining the third terminal temperature rise value according to the rated load thermal point temperature rise and the third terminal non-linear variable; obtaining the third time constant according to the rated time constant, the third starting non-linear variable and the third terminal non-linear variable; determining the thermal point temperature rise value at any time in the third stage according to the third starting temperature rise value, the third terminal temperature rise value and the third time constant; and determining the third thermal point temperature rise change relationship according to the correlation among the third starting temperature rise value, the third terminal temperature rise value, the third time constant and the thermal point temperature rise value at any time in the third stage.

[0178] As an implementation form, the high overload transformer is specifically configured to: the third load rate range comprises a third starting load rate and a third terminal load rate; the third starting load rate is equal to the second terminal load rate of the second operation stage; the third terminal load rate represents a target load rate corresponding to the third operation stage; and the third thermal point temperature rise change relationship of the third operation stage is determined according to the third load rate range, including: solving a third starting non-linear variable according to the third starting load rate and a preset empirical constant; solving a third terminal non-linear variable according to the third terminal load rate and the preset empirical constant; determining the third starting temperature rise value according to the rated load thermal point temperature rise and the third starting non-linear variable; determining the third terminal temperature rise value according to the rated load thermal point temperature rise and the third terminal non-linear variable; obtaining the third time constant according to the rated time constant, the third starting non-linear variable and the third terminal non-linear variable; determining the thermal point temperature rise value at any time in the third stage according to the third starting temperature rise value, the third terminal temperature rise value and the third time constant; and determining the third thermal point temperature rise change relationship according to the correlation among the third starting temperature rise value, the third terminal temperature rise value, the third time constant and the thermal point temperature rise value at any time in the third stage.

[0179] As an implementation form, the high overload transformer is specifically configured to: the third load rate range comprises a third starting load rate and a third terminal load rate; the third starting load rate is equal to the second terminal load rate of the second operation stage; the third terminal load rate represents a target load rate corresponding to the third operation stage; and the third thermal point temperature rise change relationship of the third operation stage is determined according to the third load rate range, including: solving a third starting non-linear variable according to the third starting load rate and a preset empirical constant; solving a third terminal non-linear variable according to the third terminal load rate and the preset empirical constant; determining the third starting temperature rise value according to the rated load thermal point temperature rise and the third starting non-linear variable; determining the third terminal temperature rise value according to the rated load thermal point temperature rise and the third terminal non-linear variable; obtaining the third time constant according to the rated time constant, the third starting non-linear variable and the third terminal non-linear variable; determining the thermal point temperature rise value at any time in the third stage according to the third starting temperature rise value, the third terminal temperature rise value and the third time constant; and determining the third thermal point temperature rise change relationship according to the correlation among the third starting temperature rise value, the third terminal temperature rise value, the third time constant and the thermal point temperature rise value at any time in the third stage.

[0180] As an implementation form, the high overload transformer is specifically configured to: the third load rate range comprises a third starting load rate and a third terminal load rate; the third starting load rate is equal to the second terminal load rate of the second operation stage; the third terminal load rate represents a target load rate corresponding to the third operation stage; and the third thermal point temperature rise change relationship of the third operation stage is determined according to the third load rate range, including: solving a third starting non-linear variable according to the third starting load rate and a preset empirical constant; solving a third terminal non-linear variable according to the third terminal load rate and the preset empirical constant; determining the third starting temperature rise value according to the rated load thermal point temperature rise and the third starting non-linear variable; determining the third terminal temperature rise value according to the rated load thermal point temperature rise and the third terminal non-linear variable; obtaining the third time constant according to the rated time constant, the third starting non-linear variable and the third terminal non-linear variable; determining the thermal point temperature rise value at any time in the third stage according to the third starting temperature rise value, the third terminal temperature rise value and the third time constant; and determining the third thermal point temperature rise change relationship according to the correlation among the third starting temperature rise value, the third terminal temperature rise value, the third time constant and the thermal point temperature rise value at any time in the third stage.

[0181] Figure 4 is a schematic diagram of a thermal point temperature rise determination device provided by the present application. As Figure 4 The thermal point temperature rise determination device 60 can include at least one first processor 601 and a memory 603 for storing processor-executable instructions. The first processor 601 is configured to execute the instructions in the memory 603 to implement the thermal point temperature rise determination method in the following embodiments.

[0182] In addition, the hotspot temperature rise determination device 60 can further include a communication bus 602, at least one communication interface 604, an input device 606, and an output device 605.

[0183] The first processor 601 can be a central processing unit (CPU), a micro-processing unit, an ASIC, or one or more integrated circuits for controlling the execution of programs of the present application.

[0184] The communication bus 602 can include a path for transmitting information between the above-mentioned components.

[0185] The communication interface 604 can be used for communication with other devices or communication networks, such as Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc., using any transceiver-like device.

[0186] The input device 606 can be used to receive input signals, and the output device 605 can be used to output signals.

[0187] The memory 603 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, a magnetic disk storage or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited thereto. The memory can exist independently, and be connected to the processing unit through a bus. The memory can also be integrated with the processing unit.

[0188] The memory 603 is used to store instructions for executing the programs of the present application, and the first processor 601 is used to control the execution. The first processor 601 is used to execute the instructions stored in the memory 603, thereby realizing the functions in the hotspot temperature rise determination method of the present application.

[0189] In particular implementations, as one example, the first processor 601 can include one or more CPUs, such as CPU0 and CPU1 in Figure 4

[0190] In particular implementations, as one example, the hotspot temperature rise determination device 60 can include multiple processors, such as the first processor 601 and the second processor 607 in Figure 4 Each of these processors can be a single-CPU processor or a multi-CPU processor. A processor here can refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0191] The hotspot temperature rise determination device includes, as shown in Figure 4 the first processor 601 and a memory 603 storing executable instructions for the first processor 601; wherein the first processor 601 is configured to execute the executable instructions to implement the hotspot temperature rise determination method of any possible implementation above. And achieve the same technical effects, to avoid repetition, here will not repeat.

[0192] The embodiments of the present application also provide a computer readable storage medium, when the instructions in the computer readable storage medium are executed by the processor of the hotspot temperature rise determination device, the hotspot temperature rise determination device can execute the hotspot temperature rise determination method of any possible implementation above. And achieve the same technical effects, to avoid repetition, here will not repeat.

[0193] The embodiments of the present application also provide a computer program product, including computer programs or instructions, computer programs or instructions are executed by the processor to implement the hotspot temperature rise determination method of any possible implementation above. And achieve the same technical effects, to avoid repetition, here will not repeat.

[0194] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only and the true scope and spirit of the application is indicated by the following claims. The true scope and spirit of the application is indicated by the following claims.

[0195] It should be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is indicated by the appended claims, rather than the description and examples.​

Claims

1. A method for determining hotspot temperature rise, characterized in that, The method is applied to a high overload transformer, and comprises the following steps: determining a plurality of load rates of the high overload transformer in a preset period of operation; the operation process represents the load change of the high overload transformer in different time periods or working conditions in the preset period; discretizing the operation process into a plurality of operation stages according to the size range of the plurality of load rates; one operation stage corresponds to one load rate range; determining the hot spot temperature rise change relationship between the hot spot temperature rise and time in the corresponding load rate range of each operation stage; combining and processing the hot spot temperature rise change relationship of each operation stage to obtain a target hot spot temperature rise curve; determining the hot spot temperature rise limit value of the high overload transformer according to the target hot spot temperature rise curve; the hot spot temperature rise limit value includes a minimum temperature rise limit value and a maximum temperature rise limit value.

2. The hot spot temperature rise determination method according to claim 1, characterized by, The plurality of operation stages include a first operation stage, a second operation stage and a third operation stage; The discretization of the operation process into a plurality of operation stages according to the size range of the plurality of load rates comprises the following steps: sorting according to the size range of the plurality of load rates; discretizing the operation process into a plurality of operation stages according to the relationship between each load rate and the operation duration corresponding to the load rate; The first load rate range in the first operation stage is lower than the second load rate range in the second operation stage, and the second load rate range in the second operation stage is lower than the third load rate range in the third operation stage.

3. The hot spot temperature rise determination method according to claim 2, characterized by, The determination of the hot spot temperature rise change relationship between the hot spot temperature rise and time in the corresponding load rate range of each operation stage comprises the following steps: determining a first starting temperature rise value, a first terminal temperature rise value, a first time constant and a hot spot temperature rise value at any time in the first stage according to the first load rate range, so as to determine the first hot spot temperature rise change relationship of the first operation stage; and determining a second starting temperature rise value, a second terminal temperature rise value, a second time constant and a hot spot temperature rise value at any time in the second stage according to the second load rate range, so as to determine the second hot spot temperature rise change relationship of the second operation stage; and determining a third starting temperature rise value, a third terminal temperature rise value, a third time constant and a hot spot temperature rise value at any time in the third stage according to the third load rate range, so as to determine the third hot spot temperature rise change relationship of the third operation stage.

4. The hot spot temperature rise determination method according to claim 3, characterized by, The method further comprises the following steps: obtaining the winding average temperature rise under rated load; solving the winding hot spot temperature rise under rated load according to the winding average temperature rise under rated load and a preset hot spot temperature coefficient to obtain a rated load hot spot temperature rise; determining the rated time constant of the winding under rated load condition according to the rated load hot spot temperature rise; the time constant represents the time node when the hot spot temperature rise curve tends to be stable.

5. The hot spot temperature rise determination method according to claim 4, characterized by, The first load rate range includes a first starting load rate and a first terminal load rate; the initial load rate represents the load rate when the no-load loss is in the first operation stage; the first terminal load rate represents the target load rate corresponding to the first operation stage; The first hot spot temperature rise change relationship is determined according to the first starting load rate range, the first starting point temperature rise value, the first terminal point temperature rise value, the first time constant and the hot spot temperature rise value at any time in the first stage. The first starting point nonlinear variable is solved according to the first starting load rate and a preset empirical constant, and the first terminal point nonlinear variable is solved according to the first terminal load rate and the preset empirical constant; The first starting point temperature rise value is determined according to the rated load hot spot temperature rise and the first starting point nonlinear variable, and the first terminal point temperature rise value is determined according to the rated load hot spot temperature rise and the first terminal point nonlinear variable; The first time constant is obtained according to the rated time constant, the first starting point nonlinear variable and the first terminal point nonlinear variable; The hot spot temperature rise value at any time in the first stage is determined according to the first starting point temperature rise value, the first terminal point temperature rise value and the first time constant; The first hot spot temperature rise change relationship is determined according to the correlation relationship among the first starting point temperature rise value, the first terminal point temperature rise value, the first time constant and the hot spot temperature rise value at any time in the first stage.

6. The hot spot temperature rise determination method of claim 4, wherein, The second load rate range includes the second starting load rate and the second terminal load rate; the second starting load rate is equal to the first terminal load rate of the first running stage; and the second terminal load rate represents a target load rate corresponding to the second running stage. The second hot spot temperature rise change relationship is determined according to the second starting point temperature rise value, the second terminal point temperature rise value, the second time constant and the hot spot temperature rise value at any time in the second stage, so as to determine the second running stage. The second starting point nonlinear variable is solved according to the second starting load rate and a preset empirical constant, and the second terminal point nonlinear variable is solved according to the second terminal load rate and the preset empirical constant; The second starting point temperature rise value is determined according to the rated load hot spot temperature rise and the second starting point nonlinear variable, and the second terminal point temperature rise value is determined according to the rated load hot spot temperature rise and the second terminal point nonlinear variable; The second time constant is obtained according to the rated time constant, the second starting point nonlinear variable and the second terminal point nonlinear variable; The hot spot temperature rise value at any time in the second stage is determined according to the second starting point temperature rise value, the second terminal point temperature rise value and the second time constant; The second hot spot temperature rise change relationship is determined according to the correlation relationship among the second starting point temperature rise value, the second terminal point temperature rise value, the second time constant and the hot spot temperature rise value at any time in the second stage.

7. The hot spot temperature rise determination method of claim 3, wherein, The third load rate range includes the third starting load rate and the third terminal load rate; the third starting load rate is equal to the second terminal load rate of the second running stage; and the third terminal load rate represents a target load rate corresponding to the third running stage. The third starting point temperature rise value, the third terminal point temperature rise value, the third time constant and the hot spot temperature rise value at any time in the third stage are determined according to the third load rate range, so as to determine the third hot spot temperature rise change relationship in the third operation stage, including: A third starting point nonlinear variable is solved according to the third starting load rate and a preset empirical constant, and a third terminal point nonlinear variable is solved according to the third terminal load rate and the preset empirical constant; The third starting point temperature rise value is determined according to the rated load hot spot temperature rise and the third starting point nonlinear variable, and the third terminal point temperature rise value is determined according to the rated load hot spot temperature rise and the third terminal point nonlinear variable; A third time constant is obtained according to the rated time constant, the third starting point nonlinear variable and the third terminal point nonlinear variable; The hot spot temperature rise value at any time in the third stage is determined according to the third starting point temperature rise value, the third terminal point temperature rise value and the third time constant; The third hot spot temperature rise change relationship is determined according to the correlation relationship among the third starting point temperature rise value, the third terminal point temperature rise value, the third time constant and the hot spot temperature rise value at any time in the third stage.

8. The hot spot temperature rise determination method of claim 3, wherein, The hot spot temperature rise change relationships of the operation stages are combined to obtain a target hot spot temperature rise curve, including: The first hot spot temperature rise change relationship, the second hot spot temperature rise change relationship and the third hot spot temperature rise change relationship are combined to obtain the target hot spot temperature rise curve.

9. The hot spot temperature rise determination method of claim 8, wherein, The hot spot temperature rise limit value of the high overload transformer is determined according to the target hot spot temperature rise curve, including: The starting point temperature rise value of the target hot spot temperature rise curve is determined as the minimum temperature rise limit value; The terminal point temperature rise value of the target hot spot temperature rise curve is determined as the maximum temperature rise limit value.

10. A high overload transformer characterized by The high overload transformer includes a core and a winding; the core is a magnetic conductive material, the magnetic permeability of the magnetic conductive material is higher than a preset magnetic permeability, and the loss of the magnetic conductive material is lower than a preset loss; the heat resistance grade of the winding is F grade and above, and the winding is a dry type ceramic insulation structure, configured to perform the hot spot temperature rise determination method in any one of claims 1-9.

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