A design method for transformer aliasing core and aliasing core

Abstract

The present invention discloses a design method for a transformer aliasing core and an aliasing core, and belongs to the technical field of transformers. Among the existing electrical steels of different performance levels, two electrical steels with the lowest total cost are selected for aliasing through cost calculation; different proportions of the two electrical steels are selected for aliasing, and different aliasing proportions are simulated and analyzed using electromagnetic field simulation software, and actual transformer tests are performed to measure the core loss value of the aliasing core to obtain the best core aliasing proportion. Through this design method, the best core aliasing combination with the lowest core loss can be selected from the core aliasing combination with the lowest total cost, and the core loss can be effectively reduced without increasing the quality and cost of the transformer, thereby improving the efficiency and performance of the transformer and meeting the requirements of modern power equipment for economic, efficient and compact design.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a design method for a transformer aliasing core and the aliasing core. Background Art

[0002] In a transformer, the iron core is a key component that conducts magnetic fields and provides magnetic coupling. However, during the operation of the transformer, the iron core undergoes magnetization and magnetization reversal, which causes hysteresis loss and eddy current loss in the iron core, resulting in energy loss and temperature rise. These losses not only affect the efficiency of the transformer, but may also cause overheating and failure of the equipment.

[0003] At present, transformer cores are usually made of the same grade of electrical steel (silicon steel sheets), and their magnetic properties directly determine the no-load power loss of the transformer, which is mainly composed of core loss and copper loss. In order to reduce core loss, traditional methods include increasing the cross-sectional area of ​​the core or using materials with high magnetic permeability. However, these methods usually lead to an increase in the size and weight of the transformer and an increase in cost, which cannot meet the requirements of modern power equipment for economical, efficient and compact design. Summary of the invention

[0004] The object of the present invention is to provide a design method and a hybrid iron core of a transformer, aiming to solve at least one of the technical problems existing in the above-mentioned prior art. To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows:

[0005] A method for designing a transformer aliasing core comprises the following steps:

[0006] S1, taking the reference core steel grade as the standard, among the existing electrical steels of different performance grades, two electrical steels with the lowest total cost are selected through cost calculation;

[0007] S2, select different ratios for aliasing of the two types of electrical steel, use electromagnetic field simulation software to simulate and analyze different aliasing ratios, and conduct actual transformer tests to measure the core loss value of the aliasing core to obtain the optimal core aliasing ratio.

[0008] As a further solution of the present invention: Step S1 comprises the following steps:

[0009] S11, select electrical steel with at least the same core loss grade as the reference core steel grade;

[0010] S12, selecting a number of high-performance electrical steels having at least a core loss value better than a reference core steel grade and a number of low-performance electrical steels having at least a core loss value worse than a reference core steel grade;

[0011] S13, arranging and combining a plurality of high-performance electrical steels and a plurality of low-performance electrical steels, each combination comprising one high-performance electrical steel and one low-performance electrical steel;

[0012] S14, according to the market price of high-performance electrical steel and the market price of low-performance electrical steel, with the hybrid core and the reference core having equal quality and the hybrid core manufacturing cost not exceeding the reference core manufacturing cost as the standard, calculate and select a hybrid core combination that meets the standard;

[0013] S15, using electromagnetic field simulation software to simulate and analyze different aliasing core combinations, and performing actual transformer tests to measure the core loss values ​​of the aliasing cores, and selecting the aliasing core combinations whose core loss is reduced by more than 1% compared with the reference core;

[0014] S16, calculating the core aliasing combination with the lowest total cost according to the manufacturing cost calculated in step S14 and the core loss cost calculated in step S15.

[0015] As a further solution of the present invention: step S2 comprises the following steps:

[0016] S21, in the core aliasing combination with the lowest total cost, high-performance electrical steel and low-performance electrical steel are aliased in different proportions;

[0017] S22, finite element simulation and post-processing algorithm are performed on the core with different proportions of steel grades and the core loss is measured on the actual transformer;

[0018] S23, finally selecting the best core aliasing combination with the lowest core loss from the core aliasing combinations with the lowest total cost.

[0019] As a further solution of the present invention: the calculation in step S14 to select the aliased core combination that meets the standard must satisfy the following two formulas at the same time:

[0020] ,

[0021] ,

[0022] Where CMC3 is the reference core manufacturing cost, CMC 12 Manufacturing cost of hybrid core, m core is the mass of the reference core, C S3 is the market price of the reference core, C S1 is the market price of high performance electrical steel, α is the mass ratio of high performance electrical steel, C S2 The market price for low-performance electrical steel.

[0023] As a further solution of the present invention: the core aliasing combination with the lowest total cost calculated in step S16 is defined as:

[0024] ，

[0025] Where TCO is the total cost of the hybrid core, and IC is the initial cost, which includes the manufacturing cost of the hybrid core CMC 12 , P 12 is the aliasing core loss, and variable A represents the allocated cost per watt of no-load loss.

[0026] As a further embodiment of the present invention, the variable A is defined as follows:

[0027] ,

[0028] Where, t is the operating time of the transformer. ， n is the expected service life of the transformer, t and n are both natural numbers greater than or equal to 0, i is the annual investment discount rate, is the energy cost over the mid-life of the transformer.

[0029] As a further solution of the present invention: the energy cost in the middle of the transformer life is defined as follows:

[0030] ,

[0031] Where C0 is the initial cost of energy, r represents the annual growth rate of energy prices, and n is the expected service life of the transformer.

[0032] And a hybrid iron core, comprising a combination of high-performance electrical steel and low-performance electrical steel prepared according to any of the above-mentioned design methods for the hybrid iron core of the transformer.

[0033] As a further solution of the present invention: the high-performance electrical steel is stacked in the middle of the iron core, and the low-performance electrical steel is stacked on both sides of the iron core.

[0034] The present invention has the following beneficial effects:

[0035] The present invention first determines a reference iron core steel grade, then selects high-performance electrical steel with a performance grade better than the reference iron core steel grade and low-performance electrical steel with a performance grade worse than the reference iron core steel grade from the existing steel grades, and a high-performance electrical steel is aliased with a high-performance electrical steel to form an aliased iron core combination. The aliased iron core and the reference iron core have the same mass and the manufacturing cost of the aliased iron core does not exceed the manufacturing cost of the reference iron core. The aliased iron core combination that meets the manufacturing cost standard is first calculated and selected, and then the electromagnetic field simulation software is used to simulate and analyze the aliased iron core combination that meets the manufacturing cost standard. Actual transformer tests are carried out to measure the core loss value of the aliased core, and the aliased core combination with a core loss reduction of more than 1% compared with the reference core is further selected, so as to select the core aliasing combination with the lowest total cost (including manufacturing cost and core loss cost). Finally, the high-performance electrical steel and low-performance electrical steel in the core aliasing combination with the lowest total cost are aliased in different proportions, and finite element simulation and post-processing algorithm are performed as well as the actual transformer to measure the core loss. Finally, the best core aliasing combination with the lowest core loss is selected from the core aliasing combination with the lowest total cost.

[0036] Compared with the existing transformer core made of the same grade of electrical steel, the hybrid core obtained by the design method of the present invention effectively reduces the core loss and improves the efficiency and performance of the transformer without increasing the quality and cost of the transformer, thus meeting the requirements of modern power equipment for economical, efficient and compact design. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below in conjunction with the accompanying drawings.

[0038] Figure 1 It is a flow chart of a transformer core aliasing design method of the present invention;

[0039] Figure 2 is a schematic diagram of the hybrid core of the present invention;

[0040] Figure 3 It is a schematic diagram of the hierarchical layout of the hybrid core of the present invention;

[0041] Figure 4 It is a schematic diagram of the variation of the aliasing core loss with the hierarchical layout of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] See also Figure 2 As shown, the present invention provides a hybrid core of a transformer, the hybrid core includes high-performance electrical steel and low-performance electrical steel, the high-performance electrical steel is stacked in the middle of the core, and the low-performance electrical steel is stacked on both sides of the core. High-performance electrical steel is an electrical steel with high magnetic permeability, low coercive force, and low hysteresis loss. The high-performance electrical steel is placed in the middle of the core because the magnetic field strength here is the highest and the requirements for material properties are also the highest. High-performance materials can effectively reduce hysteresis losses and improve energy conversion efficiency. Low-performance electrical steel has lower performance, but has cost advantages or specific physical properties, such as better processability and lower density. Low-performance electrical steel is used on both sides of the core. The magnetic field strength in these areas is relatively low, and the requirements for material properties are not as strict as in the middle. The use of low-performance electrical steel can reduce costs to a certain extent while maintaining an acceptable level of overall performance.

[0044] See also Figure 1 As shown, the present invention also provides a method for designing a hybrid core of the transformer, taking the reference core steel type as the standard, and selecting two electrical steels with the lowest total cost from the existing electrical steels of different performance grades through cost calculation, that is, selecting high-performance electrical steel and low-performance electrical steel that meet the requirements, and stacking the high-performance electrical steel in the middle of the core, and stacking the low-performance electrical steel on both sides of the core. Then, the two electrical steels are aliased according to different mass ratios, and different aliasing ratios are simulated and analyzed using electromagnetic field simulation software, and actual transformer tests are performed to measure the core loss value of the aliased core, so as to obtain the core aliasing ratio of the two electrical steels with the lowest total cost and the smallest core loss.

[0045] Specifically, the above method includes at least the following steps:

[0046] Step a: According to the design requirements and the specifications of electrical steel, select electrical steel with the same performance level as the reference core steel grade, and the mass m of the reference core core， The market price is C S3 .

[0047] Step b, selecting several high-performance electrical steels with performance levels better than the reference core steel and several low-performance electrical steels with performance levels worse than the reference core steel, the quality of the electrical steels being selected based at least on their specific loss values ​​provided by the manufacturer at a polarization amplitude of 1.7 T and a magnetization frequency of 50 Hz.

[0048] Step c: determining the high-performance electrical steel grade and the low-performance electrical steel grade according to the total cost of the hybrid core.

[0049] Firstly, according to the market price of high-performance electrical steel and the market price of low-performance electrical steel, a hybrid core combination that meets the standard is calculated and selected with the standard that the quality of the hybrid core is equal to that of the reference core and the manufacturing cost of the hybrid core does not exceed the manufacturing cost of the reference core.

[0050] Specifically, the manufacturing cost of the hybrid core is determined by the mass ratio of high-performance electrical steel and low-performance electrical steel and the specific price. In order to facilitate comparison with the reference core, it is necessary to ensure that the mass of the hybrid core is equal to that of the reference core and the cost does not increase.

[0051] The mass of the aliasing core and the reference core is the same, m core , assuming that high performance electrical steel P S1 Mass ratio of α and low performance electrical steel P S2 The mass ratio of high-performance electrical steel is 1-α, so that high-performance electrical steel is located in the middle of the core and low-performance electrical steel is located on both sides of the core, which can effectively reduce the core loss. S1 The market price of C S1 , low performance electrical steel P S2 The market price of C S2 And the proportion of steel grades, calculate the manufacturing cost CMC of the hybrid core 12 , and compared with the manufacturing cost CMC3 of the reference core, the mass ratio of the aliased core is calculated. The formula is as follows:

[0052] ,

[0053] .

[0054] Secondly, after selecting the aliasing core combinations that meet the standards, we use electromagnetic field simulation software to simulate and analyze different aliasing core combinations, and conduct actual transformer tests to measure the core loss values ​​of the aliasing cores. We further select the aliasing core combinations whose core loss is reduced by more than 1% compared to the reference core.

[0055] Finally, the manufacturing cost and core loss cost calculated in the above steps are combined to calculate the core aliasing combination with the lowest total cost.

[0056] Specifically, the total cost of the aliasing core is defined as:

[0057] ；

[0058] Where TCO is the total cost of the hybrid core, and IC is the initial cost, which includes the manufacturing cost of the hybrid core CMC 12 , P 12 is the aliasing core loss, and variable A represents the allocated cost per watt of no-load loss.

[0059] The variable A is defined as follows:

[0060] ,

[0061] Where, t is the operating time of the transformer. ， n is the expected service life of the transformer, t and n are both natural numbers greater than or equal to 0, i is the annual investment discount rate, is the energy cost over the mid-life of the transformer.

[0062] Energy costs over the medium term of the transformer's life is defined as follows:

[0063] ,

[0064] Where C0 is the initial cost of energy, r represents the annual growth rate of energy prices, and n is the expected service life of the transformer.

[0065] Step d, see Figure 3 As shown, in the core aliasing combination with the lowest total cost, high-performance electrical steel P S1 and low performance electrical steel P S2 Mix according to different proportions, for example, 25% of high-performance electrical steel P S1 With 75% low performance electrical steel P S2 Mixed combination; 50% high performance electrical steel P S1 With 50% low performance electrical steel P S2 Mixed combination; 75% high performance electrical steel P S1 With 25% low performance electrical steel P S2 combinations of etc.

[0066] Step e, see Figure 4 As shown, the finite element simulation and post-processing algorithm are performed on the iron cores with different proportions of steel grades, and the iron core loss is measured by actual transformers. Thus, the best iron core aliasing combination with the lowest core loss is selected from the iron core aliasing combination with the lowest total cost.

[0067] The above is a detailed description of the preferred embodiments of the present invention, which cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A design method for a transformer aliasing core, characterized in that: The following steps are involved: S1, taking the reference core steel grade as the standard, among the existing electrical steels of different performance grades, two electrical steels with the lowest total cost are selected through cost calculation; S2, select different ratios for aliasing of two types of electrical steel, use electromagnetic field simulation software to simulate and analyze different aliasing ratios, and conduct actual transformer tests to measure the core loss value of the aliased core to obtain the optimal core aliasing ratio; Wherein, step S1 comprises the following steps: S11, select electrical steel with at least the same core loss grade as the reference core steel grade; S12, selecting a number of high-performance electrical steels having at least a core loss value better than a reference core steel grade and a number of low-performance electrical steels having at least a core loss value worse than a reference core steel grade; S13, arranging and combining a plurality of high-performance electrical steels and a plurality of low-performance electrical steels, each combination comprising one high-performance electrical steel and one low-performance electrical steel; S14, according to the market price of high-performance electrical steel and the market price of low-performance electrical steel, with the hybrid core and the reference core having equal quality and the hybrid core manufacturing cost not exceeding the reference core manufacturing cost as the standard, calculate and select a hybrid core combination that meets the standard; The calculation to select a standard aliasing core combination must satisfy the following two formulas at the same time: ， ， Where CMC3 is the manufacturing cost of the reference core, CMC 12 Manufacturing cost of hybrid core, m core is the mass of the reference core, C S3 is the market price of the reference core, C S1 is the market price of high performance electrical steel, α is the mass ratio of high performance electrical steel, C S2 is the market price of low-performance electrical steel; S15, using electromagnetic field simulation software to simulate and analyze different aliasing core combinations, and performing actual transformer tests to measure the core loss values ​​of the aliasing cores, and selecting the aliasing core combinations whose core loss is reduced by more than 1% compared with the reference core; S16, calculating the core aliasing combination with the lowest total cost according to the manufacturing cost calculated in step S14 and the core loss cost calculated in step S15; The core aliasing combination with the lowest total cost is calculated as: ， Where TCO is the total cost of the hybrid core, and IC is the initial cost, which includes the manufacturing cost of the hybrid core CMC 12 , P 12 is the aliasing core loss, and variable A represents the allocated cost of no-load loss per watt; Wherein, the variable A is defined as follows: ， Where, t is the operating time of the transformer. ， n is the expected service life of the transformer, t and n are both natural numbers greater than or equal to 0, i is the annual investment discount rate, and Cn / 2 is the energy cost in the middle of the transformer's life; The energy cost Cn / 2 in the mid-life of the transformer is defined as follows: ， Where C0 is the initial cost of energy, r represents the annual growth rate of energy prices, and n is the expected service life of the transformer.

2. The design method of a transformer aliasing core according to claim 1 is characterized in that: Step S2 includes the following steps: S21, in the core aliasing combination with the lowest total cost, high-performance electrical steel and low-performance electrical steel are aliased in different proportions; S22, finite element simulation and post-processing algorithm are performed on the core with different proportions of steel grades and the core loss is measured on the actual transformer; S23, finally selecting the best core aliasing combination with the lowest core loss from the core aliasing combinations with the lowest total cost.

3. A hybrid core, characterized in that: It comprises a combination of high-performance electrical steel and low-performance electrical steel prepared according to the design method of a transformer hybrid iron core as described in any one of claims 1 or 2.

4. The hybrid core according to claim 3, characterized in that: The high-performance electrical steel is stacked in the middle of the iron core, and the low-performance electrical steel is stacked on both sides of the iron core.

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