A method for optimizing structure of non-crystalline-silicon steel combined three-dimensional roll core power distribution transformer

Abstract

The application discloses a kind of amorphous-silicon steel combined three-dimensional wound core power distribution transformer structure optimization method, belongs to the field of combined three-dimensional wound core.Firstly, the amorphous-silicon steel combined three-dimensional wound core structure using silicon steel material in inner layer, using amorphous material in outer layer is determined, and then the structural parameters of amorphous-silicon steel combined three-dimensional wound core power distribution transformer are determined, then the structural parameters are used as optimization variable, the structural optimization model of amorphous-silicon steel combined three-dimensional wound core power distribution transformer is established, finally minimum no-load loss and A metering weight sound pressure level minimum are used as optimization goal, and the structural optimization model is solved using multi-objective optimization algorithm, and the optimal structural parameters of amorphous-silicon steel combined three-dimensional wound core power distribution transformer are obtained.The application proposes the combined three-dimensional wound core structure that can comprehensively amorphous and silicon steel respective advantages, and the structural parameters of combined three-dimensional wound core are optimized design, and amorphous-silicon steel combined three-dimensional wound core power distribution transformer with low no-load loss, low vibration noise is obtained.

Description

Technical Field

[0001] This invention relates to the field of composite wound cores, and in particular to a method for optimizing the structure of a distribution transformer with an amorphous-silicon steel composite three-dimensional wound core. Background Technology

[0002] Amorphous alloys and grain-oriented silicon steel are two commonly used soft magnetic materials for manufacturing the cores of three-dimensional wound distribution transformers. Amorphous alloys have advantages such as high permeability and low loss density, resulting in low no-load losses in amorphous distribution transformers. However, they also have disadvantages such as low saturation flux density, high magnetostriction coefficient, small lamination factor, poor mechanical toughness, and low impact resistance, leading to high noise, low design magnetic flux density, large size, and poor short-circuit withstand capability in amorphous alloy distribution transformers. Grain-oriented silicon steel, on the other hand, has high saturation flux density, low magnetostriction coefficient, large lamination factor, and high mechanical toughness, resulting in good core processing performance, high design magnetic flux density, small size, and low noise in silicon steel distribution transformers. However, its relatively low permeability and high loss density lead to high no-load losses. The electromagnetic characteristics of these two soft magnetic materials mean that current distribution transformers cannot simultaneously achieve both low no-load losses and low vibration and noise.

[0003] Therefore, a combined three-dimensional wound core structure that integrates the advantages of amorphous steel and silicon steel is proposed, and the structural parameters of the combined three-dimensional wound core are optimized. This is of great significance for reducing the no-load loss of distribution transformers and reducing the vibration and noise of distribution transformers.

[0004] Due to the presence of two soft magnetic materials, amorphous and silicon steel, and the significant difference in their permeability, the current structural design methods for three-dimensional wound distribution transformers using a single soft magnetic material are not applicable to amorphous-silicon steel combined three-dimensional wound core distribution transformers. Summary of the Invention

[0005] The purpose of this invention is to provide a method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer, which can obtain an amorphous-silicon steel composite three-dimensional wound core distribution transformer with low no-load loss and low vibration noise.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer includes:

[0008] The structure of an amorphous-silicon steel composite three-dimensional wound core is determined; the structure is that the inner layer uses silicon steel material and the outer layer uses amorphous material.

[0009] Based on the structure of the amorphous-silicon steel composite three-dimensional wound core, determine the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer;

[0010] Using the structural parameters as optimization variables, a structural optimization model for an amorphous-silicon steel composite three-dimensional wound core distribution transformer was established.

[0011] With the optimization objectives of minimizing no-load loss and minimizing A-weighted sound pressure level, a multi-objective optimization algorithm is used to solve the structural optimization model to obtain the optimal structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer.

[0012] Optionally, the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer include: silicon steel ratio x, core column diameter D, and low-voltage foil winding thickness h. ww2 Low-voltage foil winding height h wh2 d, the diameter of the high-voltage round conductor winding s1 And the number of turns in the low-voltage winding, N2.

[0013] Optionally, the structural optimization model of the amorphous-silicon steel composite three-dimensional wound core distribution transformer is as follows:

[0014]

[0015]

[0016] In the formula, P c For no-load loss, K c f is the no-load loss coefficient. BP_A and f BP_S B represents the interpolation function for the loss density curves of amorphous and silicon steel, respectively. A1 and B S1 , respectively, are the magnetic flux densities of amorphous and silicon steel, and i is the i-th harmonic content of the magnetic flux density;

[0017] G A1 and G S1 The weights of amorphous and silicon steel, respectively, in G. A1 =3l A1 S A1 ρ A1 and G S1 =3l S1 S S1 ρ S1 ;ρ A1 and ρ S1 The densities of amorphous steel and silicon steel are respectively, l A1 and l S1 These are the magnetic circuit lengths of amorphous and silicon steel, respectively; S A1 and S S1 These are the effective cross-sectional areas of single-frame amorphous steel and silicon steel, respectively;

[0018]

[0019] l S1 ≈2(Hw +W w )

[0020]

[0021]

[0022] K A and K S H represents the lamination factor of amorphous and silicon steel three-dimensional coiled iron cores, respectively. w and W w These are the window height and width of the combined three-dimensional rolled iron core, respectively;

[0023] H w =h wh2 +2d c1

[0024]

[0025] d c1 and d c2 These represent the distances from the low-voltage winding to the upper and lower yokes and the distance from the low-voltage winding to the core column, respectively. o1 and d o2 d represents the distance between the two oil passages of the high-voltage winding and the oil passage of the low-voltage winding. iso d is the distance between the isolation layers of the high and low voltage windings. int D1 represents the phase-to-phase distance of the high-voltage winding, and D2 represents the radial distance between the high-voltage and low-voltage windings, respectively.

[0026] D1=m1(d s1 +2d int1 )+d ins1 (m1-3)

[0027] D2=m2h ww2 +d ins2 (m2-2)

[0028] m1 and m2 are the number of layers in the high-voltage and low-voltage windings, respectively, d int1 d represents the insulation thickness of the round conductor in the high-voltage winding. ins1 and d ins2 These refer to the thickness of the insulating paper between the layers of the high-voltage and low-voltage windings, respectively.

[0029]

[0030] [] indicates rounding to the nearest integer; N 1max N is the number of turns in the high-voltage winding when the voltage is adjusted by a 5% tap. 1max =[U1(1+5%) / e t U1 is the maximum rated voltage on the high-voltage side, e tFor the single-turn potential of the low-voltage winding, e t =U 2rms / N2, U 2rms N represents the effective value of the rated voltage of the low-voltage winding. 11 N represents the number of turns in a single layer of the high-voltage winding. 11 =[(h wh2 -2d c3 ) / (d s1 +d int1 )],d c3 This refers to the height of the high-voltage winding end ring;

[0031] L p The sound pressure level is A-weighted; f is the operating frequency of the combined three-dimensional wound core distribution transformer; G is the total weight of the combined core, G = G A1 +G S1 ;λ A and λ S These are the magnetostriction coefficients of amorphous steel and silicon steel, respectively.

[0032] Optionally, the structural optimization model of the amorphous-silicon steel combined three-dimensional wound core distribution transformer has a total of 6 constraints;

[0033] Constraint 1: The peak magnetic flux density of amorphous materials shall not be higher than that of silicon steel, denoted as B. A1 ≤B S1 ;

[0034] Constraint 2: The current density J1 of the high-voltage winding shall not exceed 3A / mm². 2 This is expressed as J1≤3A / mm 2 ;

[0035] Constraint 3: The current density J2 of the low-voltage winding shall not exceed 3A / mm². 2 This is expressed as J2≤3A / mm 2 ;

[0036] Constraint 4: Winding loss P w Not exceeding the first-level energy consumption limit P of amorphous three-dimensional coiled distribution transformer max , represented as P w ≤P max ;

[0037] Constraint 5: The excitation current percentage I0% shall not be higher than that of a silicon steel three-dimensional coiled distribution transformer of the same specification, expressed as I0%≤0.18%;

[0038] Constraint 6: Short-circuit voltage percentage U k The percentage is not higher than that of a three-dimensional winding distribution transformer of the same specification, expressed as U. k % ≤ 4%.

[0039] Optionally, the calculation process for the magnetic flux density of amorphous and silicon steel is as follows:

[0040] Based on the initial value of the magnetic field strength of silicon steel, the magnetic field strength of amorphous materials is calculated using Ampere's circuital law.

[0041] Based on the initial value of the magnetic field strength of silicon steel and the magnetic field strength of amorphous materials, the average magnetic flux density of amorphous and silicon steel is obtained by interpolation and calculation according to the magnetization curves of amorphous and silicon steel.

[0042] Based on the principle of magnetic flux continuity, and according to the average magnetic flux density of amorphous and silicon steel, the formula Φ = 2B is used. A S A1 +2B S S S1 Calculate the magnetic flux Φ of the amorphous-silicon steel composite three-dimensional wound core; where B A and B S These are the average magnetic flux densities of amorphous steel and silicon steel, respectively;

[0043] Judgment | Φ-Φ m | Determine whether the error is less than or equal to the preset error e to obtain the judgment result; where Φ m Indicates the rated magnetic flux;

[0044] When the judgment result is negative, compare whether Φ is less than Φ. m To obtain the comparison results;

[0045] If the comparison result is Φ less than Φ m This will increase the initial value of the magnetic field strength of silicon steel by ΔH. S1 And return to the step "Based on the initial value of the magnetic field strength of silicon steel and the magnetic field strength of amorphous steel, and according to the magnetization curves of amorphous and silicon steel, interpolate to obtain the average magnetic flux density of amorphous and silicon steel"; where ΔH S1 The increase in magnetic field strength for silicon steel;

[0046] If the comparison result is that Φ is not less than Φ m This reduces the initial value of the magnetic field strength of the silicon steel by ΔH. S1 And return to the step "Based on the initial value of the magnetic field strength of silicon steel and the magnetic field strength of amorphous steel, and according to the magnetization curves of amorphous steel and silicon steel, interpolate to obtain the average magnetic flux density of amorphous steel and silicon steel".

[0047] When the judgment result indicates yes, the average magnetic flux density of amorphous and silicon steel is output as the magnetic flux density of amorphous and silicon steel.

[0048] Optionally, the formula for calculating the current density J1 of the high-voltage winding is as follows: In the formula, I1 is the effective value of the rated current on the high-voltage side;

[0049] The formula for calculating the current density J2 of the low-voltage winding is as follows: In the formula, I2 is the effective value of the rated current on the low-voltage side;

[0050] The winding loss P w The calculation formula is P w =3K w (I1 2 R1+I2 2 R2); where K w R1 is the winding loss factor; R2 and R1 are the resistances of the high-voltage and low-voltage windings, respectively. l1 and l2 are the lengths of the high-voltage and low-voltage windings, respectively;

[0051] The formula for calculating the excitation current percentage I0% is as follows: In the formula, I 0y % and I 0w % represents the active and reactive components of the excitation current, respectively. S N For the rated capacity, q A and q S These are the excitation power densities for amorphous and silicon steel, respectively.

[0052] The short-circuit voltage percentage U k The formula for calculating % is: In the formula, U kR % and U kX The percentages represent the resistance and reactance components as a percentage of the short-circuit voltage, respectively. H k Here, ρ is the reactance height of the high-voltage and low-voltage windings, and ρ is a parameter related to the reactance height and the leakage magnetic field width, ρ=1-λ / (10πH) k ), λ is the leakage magnetic field width, σ D These are parameters related to the high and low voltage winding structure. r1 and r2 are the average radii of the high-voltage and low-voltage windings, respectively. iso This is the radius of the isolation layer between the high-voltage and low-voltage windings.

[0053] A structural optimization device for an amorphous-silicon steel composite three-dimensional wound core distribution transformer, comprising:

[0054] A memory for storing computer software programs; the computer software programs are used to implement the aforementioned structural optimization method for amorphous-silicon steel composite three-dimensional wound core distribution transformers.

[0055] A processor, connected to the memory, is used to retrieve and execute the computer software program.

[0056] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0057] This invention discloses a structural optimization method for an amorphous-silicon steel composite three-dimensional wound core distribution transformer. First, an amorphous-silicon steel composite three-dimensional wound core structure with an inner layer of silicon steel and an outer layer of amorphous material is determined. Then, the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer are determined. These structural parameters are then used as optimization variables to establish a structural optimization model for the amorphous-silicon steel composite three-dimensional wound core distribution transformer. Finally, with the minimum no-load loss and the minimum A-weighted sound pressure level as optimization objectives, a multi-objective optimization algorithm is used to solve the structural optimization model, obtaining the optimal structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer. This invention proposes a composite three-dimensional wound core structure that integrates the advantages of both amorphous and silicon steel, and optimizes the structural parameters of the composite three-dimensional wound core, resulting in an amorphous-silicon steel composite three-dimensional wound core distribution transformer with low no-load loss and low vibration noise. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 A flowchart illustrating a method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer, as provided in an embodiment of the present invention.

[0060] Figure 2 Magnetization curves of amorphous materials provided in embodiments of the present invention;

[0061] Figure 3 Magnetization curve of silicon steel provided in an embodiment of the present invention;

[0062] Figure 4 A cross-sectional view of the core column of the amorphous-silicon steel composite three-dimensional coiled iron core provided in an embodiment of the present invention;

[0063] Figure 5 The single-frame three-view diagram of the amorphous-silicon steel composite three-dimensional coiled core provided in the embodiment of the present invention;

[0064] Figure 6 This is a structural diagram of an amorphous-silicon steel combined three-dimensional wound core distribution transformer provided in an embodiment of the present invention;

[0065] Figure 7 This is a diagram of a low-voltage foil winding structure provided in an embodiment of the present invention;

[0066] Figure 8 This is a structural diagram of a high-voltage round conductor winding provided in an embodiment of the present invention;

[0067] Figure 9 The loss density curve of amorphous material provided in the embodiments of the present invention;

[0068] Figure 10 The loss density curve of silicon steel provided for embodiments of the present invention;

[0069] Figure 11 A window structure diagram of a combined three-dimensional wound core provided in an embodiment of the present invention;

[0070] Figure 12 This is a diagram of the high-voltage winding interlayer insulation structure provided in an embodiment of the present invention;

[0071] Figure 13 This is a diagram of the low-voltage winding interlayer insulation structure provided in an embodiment of the present invention;

[0072] Figure 14 Magnetostriction curves of amorphous materials provided in embodiments of the present invention;

[0073] Figure 15 Magnetostriction curve of silicon steel provided for embodiments of the present invention;

[0074] Figure 16 A schematic diagram of the iterative process of the iterative method provided in the embodiments of the present invention;

[0075] Figure 17 The excitation power density curve of the amorphous material provided in the embodiment of the present invention;

[0076] Figure 18 The excitation power density curve of silicon steel provided for the embodiments of the present invention;

[0077] Figure 19 This is a schematic diagram of the Pareto optimal solution set provided in an embodiment of the present invention;

[0078] Figure 20 The diagram shows the structural optimization results of the amorphous-silicon steel combined three-dimensional wound core distribution transformer provided in the embodiments of the present invention. Detailed Implementation

[0079] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0080] The purpose of this invention is to provide a method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer, which can obtain an amorphous-silicon steel composite three-dimensional wound core distribution transformer with low no-load loss and low vibration noise.

[0081] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0082] like Figure 1 As shown, this embodiment of the invention provides a method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer, including:

[0083] Step 1: Determine the structure of the amorphous-silicon steel composite three-dimensional coiled core; the structure is that the inner layer uses silicon steel material and the outer layer uses amorphous material.

[0084] Based on the magnetization curves of amorphous and silicon steel materials, the structural form of the amorphous-silicon steel composite three-dimensional wound core is determined: the magnetization curves of amorphous and silicon steel are as follows: Figure 2 and Figure 3 As shown, the saturation magnetic flux density of amorphous materials is approximately 1.6T, while that of silicon steel is approximately 2.0T. In the combined three-dimensional wound core, to prevent the silicon steel from becoming oversaturated with the amorphous material, the working magnetic flux density of the silicon steel portion needs to be greater than that of the amorphous portion. According to Ampere's circuital law NI = Hl (where N is the number of turns of the excitation coil, I is the excitation current, H is the magnetic field strength, and l is the magnetic circuit length), when amorphous and silicon steel are connected in parallel, the magnetomotive force NI is equal, and the shorter the magnetic circuit length, the greater the magnetic field strength. Therefore, the combined three-dimensional wound core structure determined in this invention uses silicon steel as the inner layer and amorphous material as the outer layer, which makes it easier to achieve the goal of the working magnetic flux density of silicon steel being greater than that of amorphous materials.

[0085] Step 2: Determine the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer based on its structure.

[0086] The cross-sectional view of the core column and the three-view diagram of the single frame of the amorphous-silicon steel composite solid coil core are as follows: Figure 4 and Figure 5 As shown in the figure, the parameters that determine the combined three-dimensional wound core structure include the silicon steel ratio, the core column diameter, the core window height, and the core window width. Among them, the core window height and core window width are determined by the winding structure of the combined three-dimensional wound core distribution transformer.

[0087] The structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer is as follows: Figure 6 As shown, in typical three-dimensional winding distribution transformers, the low-voltage winding has a foil structure, while the high-voltage winding has a round conductor structure. The low-voltage foil winding structure is as follows: Figure 7 As shown, the high-voltage round conductor winding structure is as follows: Figure 8 As shown. Therefore, for a combined three-dimensional wound core distribution transformer with a given voltage level and rated capacity, the parameters determining its structure include the silicon steel ratio x, the core column diameter D, and the low-voltage foil winding thickness h. ww2 Low-voltage foil winding height h wh2 d, the diameter of the high-voltage round conductor winding s1 The number of turns in the low-voltage winding, N2. These six parameters are the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer determined by this invention.

[0088] Step 3: Using the structural parameters as optimization variables, establish a structural optimization model for an amorphous-silicon steel composite three-dimensional wound core distribution transformer.

[0089] To achieve energy conservation and environmental protection, the no-load loss and A-weighted sound pressure level of the amorphous-silicon steel composite three-dimensional wound core distribution transformer were selected as optimization targets. The calculation methods for the no-load loss and vibration noise of the composite core are as follows:

[0090] Regarding the no-load loss, according to Faraday's law of electromagnetic induction, the overall magnetic flux density of the composite core exhibits a sinusoidal variation. However, due to the coexistence of amorphous and silicon steel and the difference in permeability between the two materials, the magnetic flux density distribution in the amorphous and silicon steel portions of the composite core contains harmonic components. Therefore, the influence of harmonics needs to be considered when calculating the no-load loss of the composite core. The calculation formula is as follows:

[0091]

[0092] In the formula, K c The no-load loss factor is set to 1.25. This factor reflects the non-uniformity of the magnetic flux density distribution in the actual transformer core and the increased losses caused by the core manufacturing process; f BP_A and f BP_S These are the interpolation functions for the loss density curves of amorphous steel and silicon steel, respectively. The loss density curves of amorphous steel and silicon steel are shown below. Figure 9 and Figure 10 As shown; B A1 and B S1 , respectively, represent the magnetic flux density of amorphous and silicon steel; i represents the i-th harmonic content of the magnetic flux density, where only the 7th harmonic is considered when calculating the no-load loss of the combined core; G A1 and G S1 These are the weights of amorphous steel and silicon steel, respectively, calculated using the following formula:

[0093] G A1 =3l A1 S A1 ρ A1 (2)

[0094] G S1 =3lS1 S S1 ρ S1 (3)

[0095] In the formula, l A1 and l S1 These are the magnetic circuit lengths of amorphous and silicon steel, respectively; S A1 and S S1 These are the effective cross-sectional areas of single-frame amorphous steel and silicon steel, respectively; ρ A1 and ρ S1 These are the densities of amorphous steel and silicon steel, ρ. A1 =7180kg / m 3 , ρ S1 =7650kg / m 3 The formulas for calculating the magnetic circuit length and effective cross-sectional area are as follows:

[0096]

[0097] l S1 ≈2(H w +W w (5)

[0098]

[0099]

[0100] In the formula, K A and K S These are the lamination factors for amorphous and silicon steel three-dimensional coiled cores, respectively, with values ​​of 0.836 and 0.97; H w and W w These are the window height and width of the combined three-dimensional rolled iron core, and the window structure is as follows: Figure 11 As shown, its dimensions are related to the winding structure of the combined three-dimensional wound core distribution transformer, and its calculation formula is as follows:

[0101] H w =h wh2 +2d c1 (8)

[0102]

[0103] In the formula, d c1 and d c2 These are the distances from the low-voltage winding to the upper and lower yokes and the distance from the low-voltage winding to the core column, respectively, with values ​​of 12.5mm and 8.5mm; d o1 and d o2 These represent the spacing between the oil passages of the high-voltage and low-voltage windings, both set to 2.5mm. The high-voltage winding contains two oil passages, and the low-voltage winding contains one oil passage. isoThe distance between the high-voltage and low-voltage winding isolation layers is 5mm; d int D1 is the phase-to-phase distance of the high-voltage winding, taken as 5mm; D1 and D2 are the radial distances between the high-voltage and low-voltage windings, respectively, whose values ​​are related to the number of turns and layers of the high-voltage and low-voltage windings, and their calculation formulas are as follows:

[0104] D1=m1(d s1 +2d int1 )+d ins1 (m1-3) (10)

[0105] D2=m2h ww2 +d ins2 (m2-2) (11)

[0106] In the formula, m1 and m2 are the number of layers in the high-voltage and low-voltage windings, respectively. The number of layers in the low-voltage winding is its number of turns N2, and the number of layers in the high-voltage winding is determined by its total number of turns and the number of turns per layer; d int1 d represents the insulation thickness of the high-voltage winding round conductor, taken as 0.12 mm; ins1 and d ins2 These refer to the thickness of the insulating paper between the high-voltage and low-voltage winding layers, which are 0.32 mm and 0.16 mm respectively. The insulation structure between the winding layers is as follows: Figure 12 and Figure 13 As shown, where Figure 12 This is a diagram of the interlayer insulation structure of the high-voltage winding. Figure 13 This is a diagram of the interlayer insulation structure of the low-voltage winding. The formula for calculating the number of layers m1 in the high-voltage winding is:

[0107]

[0108] In the formula, [] indicates rounding to the nearest integer; N 1max N is the number of turns in the high-voltage winding when the voltage is adjusted by a 5% tap. 1max =[U1(1+5%) / e t U1 is the maximum rated voltage on the high-voltage side, e t For the single-turn potential of the low-voltage winding, e t =U 2rms / N2, U 2rms N represents the effective value of the rated voltage of the low-voltage winding. l1 N represents the number of turns in a single layer of the high-voltage winding. l1 =[(h wh2 -2d c3 ) / (d s1 +d int1 )],d c3 The height of the high-voltage winding end ring is 20mm.

[0109] Calculating the A-weighted sound pressure level of a composite three-dimensional wound core requires considering the magnetostriction coefficients of amorphous and silicon steel. The magnetostriction curves of amorphous and silicon steel are shown below. Figure 14 and Figure 15 As shown, the formula for calculating the weighted sound pressure level of the combined three-dimensional rolled core A is:

[0110]

[0111] In the formula, f is the operating frequency of the combined three-dimensional wound core distribution transformer; G is the total weight of the combined core, G = G A1 +G S1 ;λ A and λ S These are the magnetostriction coefficients of amorphous and silicon steel, respectively, which are related to the magnetic flux density distribution of the composite core.

[0112] There are six constraints in the structural optimization design of the amorphous-silicon steel composite three-dimensional wound core distribution transformer. Constraint 1 is: the peak magnetic flux density of the amorphous part should not be higher than that of the silicon steel part. A1 ≤B S1 Constraint 2 is: the current density of the high-voltage winding shall not exceed 3A / mm². 2 J1≤3A / mm 2 Constraint 3 is: the current density of the low-voltage winding shall not exceed 3A / mm². 2 J2≤3A / mm 2 Constraint 4 is: the winding loss shall not exceed the current national standard limit for the primary energy consumption of amorphous three-dimensional wound distribution transformers. Taking a 400kVA amorphous three-dimensional wound distribution transformer as an example, its primary energy consumption limit for winding loss is 3660W. w ≤3660W; Constraint 5 is: the percentage of excitation current shall not exceed that of a silicon steel three-dimensional coil distribution transformer of the same specification, I0%≤0.18%; Constraint 6 is: the percentage of short-circuit voltage shall not exceed that of a three-dimensional coil distribution transformer of the same specification, U k % ≤ 4%.

[0113] For composite cores, due to the difference in permeability between amorphous and silicon steel, Faraday's law of electromagnetic induction cannot directly yield the distribution of magnetic flux density in different parts of the amorphous and silicon steel. To address this issue, this invention uses an iterative method to calculate the magnetic flux density distribution of the composite core based on the BH curves (magnetization curves) of the amorphous and silicon steel and the magnetic circuit structure of the composite core. The iterative process is as follows: Figure 16 As shown, specifically:

[0114] ①Assume the initial value of the magnetic field strength of the inner silicon steel is H. S1 The magnetic field strength of the outer amorphous layer is calculated using Ampere's circuital law, and the formula is H. A1 =H S1 lS1 / l A1 ;

[0115] ② By comparing the BH curves of amorphous and silicon steel, and using the magnetic field strengths of the inner silicon steel layer and the outer amorphous layer as known quantities, the average magnetic flux density B of each part of the corresponding composite core is obtained by interpolation. A and B S ;

[0116] ③ Under steady-state conditions, based on the principle of magnetic flux continuity, the magnetic flux of the composite iron core is calculated using the formula Φ = 2B. A S A1 +2B S S S1 ;

[0117] ④ If the calculated value Φ is different from Φ m If the absolute value of the difference is greater than the preset error e, then the calculated magnetic flux value Φ and the rated magnetic flux Φ will be compared. m For comparison, the rated magnetic flux Φ m The calculation formula is Φ m =U 2rms / 4.44fN2, if the calculated value Φ is less than Φ m This increases the initial value H of the magnetic field strength of the inner silicon steel layer. S1 =H S1 +ΔH S1 , where ΔH S1 The increase in the magnetic field strength of the inner silicon steel layer is a positive value, and steps ①-④ are repeated; if the calculated value Φ is greater than Φ m This reduces the initial value H of the magnetic field strength of the inner silicon steel layer. S1 =H S1 -ΔH S1 And repeat steps ①-④; if the calculated value Φ is different from Φ m If the absolute value of the difference is less than or equal to the preset error e, the loop will exit and the average magnetic flux density B of each part of the combined iron core will be output. A and B S , as the magnetic flux density of amorphous and silicon steel.

[0118] Constraint 1 can be determined using the method described above.

[0119] For constraints 2 and 3, the formulas for calculating the current density of the high-voltage and low-voltage windings are as follows:

[0120]

[0121]

[0122] In the formula, I1 and I2 are the effective values ​​of the rated current on the high-voltage and low-voltage sides, respectively.

[0123] For constraint 4, the formula for calculating the winding loss of the combined three-dimensional wound core distribution transformer is:

[0124]

[0125] In the formula, K w The winding loss factor is set to 1.15. This factor is used to reflect the non-uniformity of the actual transformer winding current density distribution. R1 and R2 are the resistances of the high-voltage and low-voltage windings, respectively, and their calculation formulas are as follows:

[0126]

[0127]

[0128] In the formula, l1 and l2 are the lengths of the high-voltage and low-voltage windings, respectively, which can be calculated from the number of turns of the high-voltage and low-voltage windings and the average length of a single turn.

[0129] For constraint 5, the formula for calculating the percentage of excitation current in a combined three-dimensional wound core distribution transformer is as follows:

[0130]

[0131]

[0132]

[0133] In the formula, I 0y % and I 0w % represents the active and reactive components of the excitation current, respectively; S N Rated capacity; q S and q A These are the excitation power densities of amorphous steel and silicon steel, respectively. The excitation power density curve for amorphous steel is shown in the figure below. Figure 17 As shown, the excitation power density curve of silicon steel is as follows: Figure 18 As shown.

[0134] For constraint 6, the formula for calculating the percentage of short-circuit voltage of the combined three-dimensional wound core distribution transformer is as follows:

[0135]

[0136]

[0137]

[0138] In the formula, U kR % and U kX % represents the resistance and reactance components as a percentage of short-circuit voltage, respectively; H kThe reactance height of the high-voltage and low-voltage windings is approximately equal to the total height of the windings, in cm; ρ is a parameter related to the reactance height and the width of the leakage magnetic field, ρ = 1 - λ / (10πH) k ), λ is the leakage magnetic field width, determined by the radial distance between the high and low voltage windings, in mm; σ D The calculation formulas for parameters related to the high and low voltage winding structures are as follows:

[0139]

[0140] In the formula, r1 and r2 are the average radii of the high-voltage and low-voltage windings, respectively; r iso This is the radius of the isolation layer between the high-voltage and low-voltage windings.

[0141] Formulas (1), (13)-(16), (19) and (22) are the structural optimization models of the amorphous-silicon steel combined three-dimensional wound core distribution transformer proposed in this invention.

[0142] Step 4: Using the minimum no-load loss and the minimum A-weighted sound pressure level as optimization objectives, the structural optimization model is solved using a multi-objective optimization algorithm to obtain the optimal structural parameters of the amorphous-silicon steel combined three-dimensional wound core distribution transformer.

[0143] The structural parameters of the combined iron core distribution transformer can be obtained by optimizing the proposed model using a multi-objective algorithm.

[0144] Taking a combined three-dimensional wound core distribution transformer with a rated voltage of 10kV and a rated capacity of 400kVA as an example, a multi-objective differential evolution algorithm was used to optimize the model and obtain the Pareto optimal solution set. The selection criteria were that the no-load loss of the combined three-dimensional wound core distribution transformer was 15% lower than the first-level energy consumption (330W) of a silicon steel transformer of the same specification, and the A-weighted sound pressure level was more than 2dB(A) lower than the vibration noise (45dB(A)) of an amorphous transformer of the same specification. Figure 19 The feasible solutions shown are selected from the optimized solutions that meet the requirements. The structural parameters of the optimized solutions are shown in Table 1. Based on the optimization results shown in Table 1, the determined structure of the amorphous-silicon steel combined three-dimensional wound core distribution transformer is as follows: Figure 20 As shown.

[0145] Table 1. Optimization Results of Structural Parameters for Amorphous-Silicon Steel Composite Three-Dimensional Wound Distribution Transformers

[0146] result 0.3487 250.0mm 217.6mm 1.2mm 2.7mm 18

[0147] The beneficial effects of this invention are: to obtain an amorphous-silicon steel composite three-dimensional wound core distribution transformer with low no-load loss and low vibration noise, which plays an important role in effectively reducing power loss in the distribution network and promoting the rapid development of a green and environmentally friendly power grid.

[0148] This invention also provides a structural optimization device for an amorphous-silicon steel composite three-dimensional wound core distribution transformer, comprising:

[0149] A memory is used to store computer software programs; the computer software programs are used to implement the above-described method for optimizing the structure of amorphous-silicon steel combined three-dimensional wound core distribution transformers; a processor is connected to the memory and is used to retrieve and execute the computer software programs.

[0150] The processor includes:

[0151] A core structure determination module is used to determine the structure of an amorphous-silicon steel composite three-dimensional core; the structure is that the inner layer uses silicon steel material and the outer layer uses amorphous material.

[0152] The structural parameter determination module is used to determine the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer based on the structure of the amorphous-silicon steel composite three-dimensional wound core.

[0153] The optimization model building module is used to establish a structural optimization model of an amorphous-silicon steel composite three-dimensional wound core distribution transformer by using the structural parameters as optimization variables.

[0154] The optimization module is used to solve the structural optimization model with the optimization objectives of minimizing no-load loss and minimizing A-weighted sound pressure level, and obtain the optimal structural parameters of the amorphous-silicon steel combined three-dimensional wound core distribution transformer.

[0155] For example, the memory is a computer-readable storage medium.

[0156] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0157] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer, characterized in that, include: The structure of an amorphous-silicon steel composite three-dimensional wound core is determined; the structure is that the inner layer uses silicon steel material and the outer layer uses amorphous material. Based on the structure of the amorphous-silicon steel composite three-dimensional wound core, determine the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer; The structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer include: silicon steel percentage. x Diameter of iron core column D Low-voltage foil winding thickness h ww2 Low-voltage foil winding height h wh2 High-voltage round conductor winding diameter d s1 and the number of turns in the low-voltage winding N 2; Using the structural parameters as optimization variables, a structural optimization model for an amorphous-silicon steel composite three-dimensional wound core distribution transformer was established. With the minimum no-load loss and the minimum A-weighted sound pressure level as optimization objectives, the structural optimization model is solved using a multi-objective optimization algorithm to obtain the optimal structural parameters of the amorphous-silicon steel combined three-dimensional wound core distribution transformer. The structural optimization model of the amorphous-silicon steel composite three-dimensional wound core distribution transformer is as follows: ； ； In the formula, P c For no-load loss, K c This is the no-load loss coefficient. f BP_A and f BP_S These are the interpolation functions for the loss density curves of amorphous steel and silicon steel, respectively. B A1 and B S1 The magnetic flux densities are for amorphous steel and silicon steel, respectively. i The first of the magnetic flux density i Subharmonic content; G A1 and G S1 The weights are for amorphous steel and silicon steel, respectively. and ; ρ A1 and ρ S1 The densities are those of amorphous steel and silicon steel, respectively. l A1 and l S1 These are the magnetic circuit lengths for amorphous and silicon steel, respectively; S A1 and S S1 These are the effective cross-sectional areas of single-frame amorphous steel and silicon steel, respectively; K A and K S These are the lamination coefficients for amorphous and silicon steel three-dimensional coiled cores, respectively. H w and W w These are the window height and width of the combined three-dimensional rolled iron core, respectively; d c1 and d c2 These represent the distances from the low-voltage winding to the upper and lower yokes and the distance from the low-voltage winding to the core column, respectively. d o1 and d o2 These represent the distances between the two oil passages of the high-voltage winding and the oil passage of the low-voltage winding. d iso This refers to the distance between the isolation layers of the high-voltage and low-voltage windings. d int This refers to the distance between phases of the high-voltage winding. D 1 and D 2 represents the radial distance between the high-voltage and low-voltage windings, respectively; m 1 and m 2 represents the number of layers in the high-voltage and low-voltage windings, respectively. d int1 This refers to the insulation thickness of the round conductor in the high-voltage winding. d ins1 and d ins2 These refer to the thickness of the insulating paper between the layers of the high-voltage and low-voltage windings, respectively. [] indicates rounding to the nearest integer; N 1max This refers to the number of turns in the high-voltage winding when the voltage is adjusted by a 5% tap. N 1max =[ U 1(1+5%) / e t ], U 1 represents the maximum rated voltage on the high-voltage side. e t This represents the single-turn potential of the low-voltage winding. e t = U 2rms / N 2, U 2rms This is the effective value of the rated voltage of the low-voltage winding; This refers to the number of turns in a single layer of the high-voltage winding. =[( h wh2 -2 d c3 ) / ( d s1 + d int1 )], d c3 This refers to the height of the high-voltage winding end ring; L p The sound pressure level is A-weighted. f To determine the operating frequency of the combined three-dimensional wound core distribution transformer; G To determine the total weight of the assembled iron core, G = G A1 + G S1 ; λ A and λ S These are the magnetostriction coefficients of amorphous steel and silicon steel, respectively.

2. The method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer according to claim 1, characterized in that, The structural optimization model of the amorphous-silicon steel composite three-dimensional wound core distribution transformer has a total of 6 constraints. Constraint 1: The peak magnetic flux density of amorphous materials shall not be higher than that of silicon steel, expressed as follows: B A1 ≤ B S1 ; Constraint 2: Current density of the high-voltage winding J 1 Not higher than 3A / mm 2 , represented as J 1≤ 3A / mm 2 ; Constraint 3: Current density of the low-voltage winding J 2 Not higher than 3A / mm 2 , represented as J 2≤ 3A / mm 2 ; Constraint 4: Winding Losses P w Not exceeding the first-level energy consumption limit of amorphous three-dimensional coiled distribution transformer P max , represented as P w ≤ P max ; Constraint 5: Percentage of excitation current I 0% is not higher than that of silicon steel three-dimensional coiled distribution transformers of the same specification, and is expressed as I 0% ≤ 0.18%; Constraint 6: Short-circuit voltage percentage U k The percentage is not higher than that of a three-dimensional winding distribution transformer of the same specification, and is expressed as follows: U k %≤4%.

3. The method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer according to claim 2, characterized in that, The calculation process for the magnetic flux density of amorphous and silicon steel is as follows: Based on the initial value of the magnetic field strength of silicon steel, the magnetic field strength of amorphous materials is calculated using Ampere's circuital law. Based on the initial value of the magnetic field strength of silicon steel and the magnetic field strength of amorphous materials, the average magnetic flux density of amorphous and silicon steel is obtained by interpolation and calculation according to the magnetization curves of amorphous and silicon steel. Based on the principle of magnetic flux continuity, and according to the average magnetic flux density of amorphous and silicon steel, the formula is used. F =2 B A S A1 +2 B S S S1 Calculate the magnetic flux of an amorphous-silicon steel composite three-dimensional wound core. F In the formula, B A and B S These are the average magnetic flux densities of amorphous steel and silicon steel, respectively; Judgment | FF m Is it less than or equal to the preset error? e To obtain the judgment result; among them, F m Indicates the rated magnetic flux; When the judgment result is negative, the comparison... F Is it less than F m To obtain the comparison results; If the comparison result is F Less than F m This will increase the initial value of the magnetic field strength of silicon steel by Δ. H S1 And return to the step "Based on the initial value of the magnetic field strength of silicon steel and the magnetic field strength of amorphous steel, and according to the magnetization curves of amorphous and silicon steel, interpolate to obtain the average magnetic flux density of amorphous and silicon steel"; where Δ H S1 The increase in magnetic field strength for silicon steel; If the comparison result is F Not less than F m This will decrease the initial value of the magnetic field strength of the silicon steel by Δ. H S1 And return to the step "Based on the initial value of the magnetic field strength of silicon steel and the magnetic field strength of amorphous steel, and according to the magnetization curves of amorphous steel and silicon steel, interpolate to obtain the average magnetic flux density of amorphous steel and silicon steel". When the judgment result indicates yes, the average magnetic flux density of amorphous and silicon steel is output as the magnetic flux density of amorphous and silicon steel.

4. The method for optimizing the structure of an amorphous-silicon steel composite three-dimensional wound core distribution transformer according to claim 2, characterized in that, Current density of the high voltage winding J The formula for calculating 1 is: In the formula, I 1 represents the effective value of the rated current on the high-voltage side; Current density of the low-voltage winding J The formula for calculating 2 is: In the formula, I 2 represents the effective value of the rated current on the low-voltage side; The winding loss P w The calculation formula is In the formula, K w This is the winding loss factor; R 1 and R 2 represents the resistance of the high-voltage and low-voltage windings, respectively. , , l 1 and l 2 represents the lengths of the high-voltage and low-voltage windings, respectively; The percentage of excitation current I The formula for calculating 0% is: In the formula, I 0y %and I 0w % represent the active and reactive components of the excitation current, respectively. , , S N For rated capacity, q A and q S These are the excitation power densities for amorphous and silicon steel, respectively. The percentage of short-circuit voltage U k The formula for calculating % is: In the formula, U kR %and U kX The percentages represent the resistance and reactance components as a percentage of the short-circuit voltage, respectively. , , H k The reactance height of the high and low voltage windings, ρ These are parameters related to reactance height and leakage magnetic field width. ρ =1- λ / (10π H k ), λ The width of the leakage magnetic field. σ D These are parameters related to the high and low voltage winding structure. , r 1 and r 2 represents the average radius of the high-voltage and low-voltage windings, respectively. r iso This is the radius of the isolation layer between the high-voltage and low-voltage windings.

5. A structural optimization device for an amorphous-silicon steel combined three-dimensional wound core distribution transformer, characterized in that, include: A memory for storing computer software programs; the computer software programs are used to implement the structural optimization method for amorphous-silicon steel composite three-dimensional wound core distribution transformers as described in any one of claims 1-4; A processor, connected to the memory, is used to retrieve and execute the computer software program.

6. The structural optimization equipment for amorphous-silicon steel combined three-dimensional wound core distribution transformer according to claim 5, characterized in that, The processor includes: A core structure determination module is used to determine the structure of an amorphous-silicon steel composite three-dimensional core; the structure is that the inner layer uses silicon steel material and the outer layer uses amorphous material. The structural parameter determination module is used to determine the structural parameters of the amorphous-silicon steel composite three-dimensional wound core distribution transformer based on the structure of the amorphous-silicon steel composite three-dimensional wound core. The optimization model building module is used to establish a structural optimization model of an amorphous-silicon steel composite three-dimensional wound core distribution transformer by using the structural parameters as optimization variables. The optimization module is used to solve the structural optimization model with the optimization objectives of minimizing no-load loss and minimizing A-weighted sound pressure level, and obtain the optimal structural parameters of the amorphous-silicon steel combined three-dimensional wound core distribution transformer.

7. The structural optimization equipment for amorphous-silicon steel combined three-dimensional wound core distribution transformer according to claim 5, characterized in that, The memory is a computer-readable storage medium.

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