Electromagnetic design method, system and equipment for low-frequency hydro-generator and medium

Abstract

The invention discloses a low-frequency hydro-generator electromagnetic design method, system and device and a medium, and the method comprises the steps: selecting the main dimensions of a plurality of low-frequency hydro-generators, the main dimensions of the low-frequency hydro-generators comprising the stator inner diameter D and the equivalent length l'of a stator core; calculating the number of turns of a stator winding corresponding to the main size of each low-frequency hydro-generator, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator and the number of turns of an excitation winding on a rotor salient pole so as to form a plurality of electromagnetic design schemes of the low-frequency hydro-generator; and performing simulation verification on each low-frequency hydraulic generator electromagnetic design scheme by using the low-frequency hydraulic generator electromagnetic simulation verification model to obtain electrical parameters of each low-frequency hydraulic generator electromagnetic design scheme, and outputting the low-frequency hydraulic generator electromagnetic design scheme meeting preset electrical parameter requirements as a final design result. The method, the system, the equipment and the medium can realize the electromagnetic design of the low-frequency hydro-generator.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy and electric power engineering, and relates to an electromagnetic design method, system, equipment and medium for a low-frequency hydro-generator. Background Art

[0002] Flexible Low Frequency AC Transmission (FLFAC) uses power electronics technology to flexibly select the appropriate frequency of 0 to 50 Hz, and realizes effective conversion between industrial frequency and low frequency through high-voltage and large-capacity AC-AC inverters. The converter can realize flexible frequency conversion and many system flexible control functions to improve the power grid transmission capacity and flexible control level. It is a new and efficient AC transmission technology and may become an efficient means of source-end networking for new power systems. With the development of power electronics technology, flexible low-frequency AC transmission based on power electronics frequency conversion has technical feasibility.

[0003] In the hydropower generation system, the hydropower plant is usually far away from the load center, and most of them require long-distance power transmission. If the industrial frequency AC transmission method is adopted, the transmission capacity and transmission distance will be greatly limited by the impedance of the long-distance transmission line. Constructing a hydropower plant transmission system based on flexible low-frequency transmission technology can proportionally reduce the reactance of the hydropower transmission line, thereby greatly improving the transmission capacity of the hydropower plant. At present, the hydropower generators are designed based on the rated power of 50Hz industrial frequency. If a flexible low-frequency transmission scheme is adopted, it is necessary to set up AC-AC frequency conversion stations at the sending end hydropower plant and the receiving end grid connection point to realize the "industrial frequency-low frequency-industrial frequency" conversion. If the existing industrial frequency hydropower generator is transformed into low-frequency power generation, and the hydropower plant directly outputs low-frequency electricity, the sending end frequency conversion link can be omitted, which will greatly reduce the investment in the frequency conversion station. However, there is currently no relevant solution for the design of low-frequency power generation of turbines. It is of great significance to carry out research on low-frequency power generation of turbines for flexible low-frequency AC transmission systems of hydropower plants. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method, system, device and medium for electromagnetic design of a low-frequency hydro-generator, which can realize the electromagnetic design of a low-frequency hydro-generator.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] In one aspect of the present invention, the electromagnetic design method of the low-frequency hydro-generator of the present invention comprises:

[0007] Determine the rated parameters of low-frequency hydro-generators;

[0008] Selecting main dimensions of several low-frequency hydro-generators, wherein the main dimensions of the low-frequency hydro-generators include the stator inner diameter D and the equivalent length l' of the stator core;

[0009] Calculate the number of stator winding turns corresponding to the main dimensions of each low-frequency hydro-generator, the stator dimensions of the low-frequency hydro-generator, the rotor dimensions of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles, so as to form several electromagnetic design schemes for the low-frequency hydro-generator;

[0010] According to the rated parameters of the low-frequency hydro-generator, the electromagnetic simulation verification model of the low-frequency hydro-generator is used to simulate and verify the electromagnetic design schemes of each low-frequency hydro-generator, and the electrical parameters of each electromagnetic design scheme of the low-frequency hydro-generator are obtained. The electromagnetic design scheme of the low-frequency hydro-generator that meets the preset electrical parameter requirements is taken as the final design result and output.

[0011] The electromagnetic design method of the low-frequency hydro-generator of the present invention is further improved in that:

[0012] Furthermore, in the electromagnetic design of the low-frequency hydro-generator, the stator inner diameter D and the equivalent length l′ of the stator core satisfy:

[0013]

[0014] Among them, S i is the rated capacity of the low-frequency hydro-generator, n mec is the mechanical speed, k ω is the winding factor, A is the line current density, is the air gap flux density, l′ is the equivalent length of the stator core, and D is the inner diameter of the stator.

[0015] Furthermore, the number of stator winding turns N is determined according to formula (3): s :

[0016]

[0017] Where ω is the electrical angular velocity, E f The stator winding generates back electromotive force in the magnetic field. is the peak value of magnetic flux per pole, for:

[0018]

[0019] Where, l′ is the equivalent length of the stator core, τ p is the motor pole pitch, It is the average value of the magnetic flux density generated by one pole in the air gap.

[0020] Furthermore, the rated parameters of the low-frequency hydro-generator include the rated power, rated voltage, rated speed and rated frequency of the low-frequency hydro-generator;

[0021] The stator dimensions of the low-frequency hydro-generator include the number of stator slots, the stator slot dimensions and the height of the stator yoke;

[0022] The rotor dimensions of the low-frequency hydro-generator include rotor outer diameter, rotor salient pole dimensions and rotor yoke height.

[0023] In a second aspect of the present invention, the electromagnetic design method of the low-frequency hydro-generator of the present invention comprises:

[0024] A determination module, used for determining the rated parameters of the low-frequency hydro-generator;

[0025] A selection module is used to select the main dimensions of several low-frequency hydro-generators, wherein the main dimensions of the low-frequency hydro-generators include the stator inner diameter D and the equivalent length l' of the stator core;

[0026] A calculation module is used to calculate the number of stator winding turns corresponding to the main dimensions of each low-frequency hydro-generator, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles, so as to form several electromagnetic design schemes of the low-frequency hydro-generator;

[0027] The simulation module is used to simulate and verify the electromagnetic design schemes of various low-frequency hydro-generators according to the rated parameters of the low-frequency hydro-generators by using the electromagnetic simulation verification model of the low-frequency hydro-generators, obtain the electrical parameters of the electromagnetic design schemes of various low-frequency hydro-generators, and output the electromagnetic design schemes of the low-frequency hydro-generators that meet the preset electrical parameter requirements as the final design results.

[0028] The electromagnetic design system of the low-frequency hydro-generator of the present invention is further improved in that:

[0029] Furthermore, the stator inner diameter D and the equivalent length l' of the stator core in the electromagnetic design of the low-frequency hydro-generator satisfy:

[0030]

[0031] Among them, S i is the rated capacity of the low-frequency hydro-generator, n mec is the mechanical speed, k ω is the winding factor, A is the line current density, is the air gap flux density, l′ is the equivalent length of the stator core, and D is the inner diameter of the stator.

[0032] Furthermore, the number of turns N of the stator winding is determined according to formula (3): s :

[0033]

[0034] Where ω is the electrical angular velocity, E f The stator winding generates back electromotive force in the magnetic field. is the peak value of magnetic flux per pole, for:

[0035]

[0036] Where, l′ is the equivalent length of the stator core, τ p is the motor pole pitch, It is the average value of the magnetic flux density generated by one pole in the air gap.

[0037] Furthermore, the rated parameters of the low-frequency hydro-generator include the rated power, rated voltage, rated speed and rated frequency of the low-frequency hydro-generator;

[0038] The stator dimensions of the low-frequency hydro-generator include the number of stator slots, the stator slot dimensions and the height of the stator yoke;

[0039] The rotor dimensions of the low-frequency hydro-generator include rotor outer diameter, rotor salient pole dimensions and rotor yoke height.

[0040] In a third aspect of the present invention, the computer device of the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the electromagnetic design method of the low-frequency hydro-generator when executing the computer program.

[0041] In a fourth aspect of the present invention, the computer-readable storage medium of the present invention stores a computer program, and when the computer program is executed by a processor, the steps of the low-frequency hydro-generator electromagnetic design method are implemented.

[0042] The present invention has the following beneficial effects:

[0043] The electromagnetic design method, system, equipment and medium of the low-frequency hydro-generator described in the present invention, during specific operation, takes the stator inner diameter D and the equivalent length l' of the stator core as variables to determine the number of stator winding turns, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles. The stator inner diameter D and the equivalent length l' of the stator core that meet the preset electrical parameter requirements and their corresponding number of stator winding turns, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles are determined by simulation, so as to realize the electromagnetic design of the low-frequency hydro-generator, provide a theoretical basis for the prototype development of the low-frequency hydro-generator, and provide a new and efficient solution for the transmission system of large-capacity medium and long-distance hydropower plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0045] Figure 1a It is the structural diagram of the low frequency power transmission system;

[0046] Figure 1b It is a structural diagram of the low frequency power transmission system of the present invention;

[0047] Figure 2 is a flow chart of the method of the present invention;

[0048] Figure 3a This is the simulation result diagram of the industrial frequency hydro-generator;

[0049] Figure 3b This is the simulation result diagram of the low-frequency hydro-generator;

[0050] Figure 4 It is the waveform diagram of the three-phase output back electromotive force of the low-frequency hydro-generator;

[0051] Figure 5 It is the A-phase self-inductance waveform of the low-frequency hydro-generator;

[0052] Figure 6 It is a system structure diagram of the present invention. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0054] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0055] The present invention is applied to the low-frequency transmission system of a hydropower plant, such as Figure 1b As shown, it aims to solve Figure 1a In the traditional solution shown in , the turbine's industrial frequency power generation is sent out through the low-frequency system, and an additional AC-AC frequency conversion station is required on the power generation side, which brings about economic and safe operation risk problems.

[0056] Embodiment 1

[0057] refer to Figure 2 The electromagnetic design method of a low-frequency hydro-generator suitable for a flexible low-frequency power transmission system of the present invention comprises the following steps:

[0058] 1) Determine the rated parameters of the low-frequency hydro-generator;

[0059] The low-frequency hydro-turbine generator is a salient-pole synchronous motor. The rated parameters of the low-frequency hydro-turbine generator are determined according to the actual engineering requirements. The rated parameters of the low-frequency hydro-turbine generator include rated power, rated voltage, rated speed and rated frequency (commonly 20Hz or 50 / 3Hz), etc. The initial design parameter of the low-frequency hydro-turbine generator, the number of pole pairs p, is obtained as follows:

[0060]

[0061] Among them, n mec is the rated speed of the low-frequency hydro-turbine generator, and f is the rated frequency of the low-frequency hydro-turbine generator.

[0062] It should be noted that the present invention performs electromagnetic design on the low-frequency hydro-generator without changing the prime mover, ie, the hydro-turbine, so it is critical to determine the number of pole pairs of the low-frequency hydro-generator according to rated parameters.

[0063] 2) Determine the main dimensions of the low-frequency hydro-generator;

[0064] The main dimensions of the low-frequency hydro-generator include the stator inner diameter D and the equivalent length l' of the stator core. The stator inner diameter D and the equivalent length l' of the stator core satisfy the following relationship:

[0065]

[0066] Among them, S i is the rated capacity of the low-frequency hydro-generator, n mec is the mechanical speed, k ω is the winding factor, which is related to the winding distribution, A is the line current density, is the air gap flux density.

[0067] It should be noted that in order to solve the stator inner diameter D and the equivalent length l' of the stator core, it is necessary to calculate the line current density and air gap flux density parameters. The specific determination process is:

[0068] 21) Line current density A;

[0069] The value of line current density A is related to the capacity of each pole, insulation level and cooling method, and the relationship between power generation efficiency, power density and economic cost must be coordinated. According to calculations, the value of A in the electromagnetic design of low-frequency hydro-generators can refer to the same-level hydro-generators with the same insulation level and cooling method.

[0070] 22) Air gap flux density

[0071] Air gap flux density The value is related to the utilization efficiency of the core material and the iron loss of the core. After calculation, it is found that in the electromagnetic design of low-frequency hydro-generators The value of can be referred to the same level of hydro-turbine generator.

[0072] The preliminary values ​​of the electric load and the magnetic load can be obtained by step 21 and step 22. In the subsequent motor characteristic verification, when the motor characteristics do not meet expectations, the values ​​of the electric load and the magnetic load can be revised.

[0073] In summary, under the conditions of given rated capacity and speed, the product of the stator inner diameter D and the equivalent length l' of the stator core is a certain value, that is, the volume of the effective part of the generator is basically determined. In addition, the stator inner diameter D and the equivalent length l' of the stator core have the following physical meanings and influence relationships:

[0074] a) The control of the equivalent length l' of the stator core will directly affect the overall performance of the unit and the quality control of the unit installation process. Under the premise of meeting the rated capacity, the shorter the overall height of the core, the easier it is to ensure the installation quality of the core punching during stacking and assembly, and it is also conducive to heat dissipation and ventilation. Good heat dissipation and ventilation will make the temperature rise distribution of the stator wire rods in the axial direction more uniform.

[0075] b) Shortening the equivalent length l' of the stator core will increase the radius of the stator, which will directly increase the mechanical stress of the rotating parts, thus increasing the mechanical properties of the materials used and the manufacturing cost. The mechanical stress of the rotating parts will be greatly increased, and the mechanical strength requirements of the corresponding materials will also become higher.

[0076] According to formula (2), after the value of the stator inner diameter D is preliminarily set, the equivalent length l' of the stator core is calculated. In this way, D and l' can be designed through multiple combinations as subsequent input parameters. The design results under different schemes are compared with the expected results, and the ideal stator inner diameter D and stator core equivalent length l' of the low-frequency hydro-turbine generator are selected. Among them, the expected results are determined according to the comprehensive design requirements of parameters such as magnetic flux saturation, voltage, frequency, resistance, inductance, etc. The design results are consistent with the expected results, that is, the ideal stator inner diameter D and stator core equivalent length l' of the low-frequency hydro-turbine generator.

[0077] 3) Determine the number of stator winding turns;

[0078] The stator winding generates a back electromotive force E in the magnetic field f for:

[0079]

[0080] Where ω is the electrical angular velocity, N s is the number of series turns of one phase winding of the stator, is the peak value of magnetic flux per pole.

[0081] Peak flux per pole for:

[0082]

[0083] Among them, τ p is the motor pole pitch, is the average value of the magnetic flux density generated by a pole in the air gap. In the case of a sinusoidal distribution of magnetic flux density, α i =2 / π.

[0084] Based on the determination of the number of pole pairs p of the low-frequency generator and the inner diameter D of the stator of the low-frequency generator, according to the pole pitch τ p=πD / (2p) and the air gap flux density determined in step 2) Get the peak value of the magnetic flux per pole of the low-frequency generator.

[0085] The no-load back electromotive force is taken as 1 to 1.2 times the rated voltage to obtain the number of stator winding turns N of the final low-frequency generator. s .

[0086] 4) Determine the stator size of the low-frequency hydro-generator;

[0087] The stator dimensions of the low-frequency hydro-generator include the number of stator slots, the stator slot dimensions and the height of the stator yoke.

[0088] 41) Determine the number of stator slots;

[0089] The value of the parallel branch is determined by selecting the slot current value of the low-frequency generator. After the insulation level of the low-frequency generator is determined, the slot current is related to the capacity, voltage, number of parallel branches and winding type of the generator. In addition, the value of the slot current needs to take into account the influence of two aspects: 1) The copper loss and additional loss caused by excessive slot current will affect the insulation temperature difference and increase the difficulty of manufacturing; 2) Too small slot current affects the effective material utilization rate and economic benefits of the generator. For example, the slot current experience value of air-cooled units at home and abroad generally does not exceed 7000A.

[0090] At the same time, the more slots the motor stator has, the more sinusoidal the magnetomotive force distribution generated by the multi-phase winding will be. However, too many slots can easily lead to oversaturation of the stator slot teeth. s After that, the number of slots Q is required s Combined with the number of parallel branches a, ensure that the number of conductors per slot Z is an integer, where Z is:

[0091]

[0092] Among them, m is the number of phases of the stator winding of the low-frequency hydro-generator, which is usually 3.

[0093] Get the slot current I u for:

[0094]

[0095] Among them, I s is the rated phase current of the low-frequency hydro-generator, Q s is the number of stator slots of the low-frequency hydro-generator.

[0096] According to equations (5) and (6), the slot current experience of the same-class units with the same cooling method is taken into account, and the number of slots Q is taken into account. s In combination with the number of parallel branches a, determine the number of stator slots and the number of parallel branches of the low-frequency hydro-generator.

[0097] 42) Determine the stator slot size;

[0098] By determining the number of stator slots, the stator slot size, i.e. the slot width b, can be determined. u and slot height h u , slot width b u and slot height h u for:

[0099] b u =(0.15~0.45)τ u (7)

[0101] h u =(4.5~7.5)b u (8)

[0103] Among them, τ u is the stator slot pitch of the low-frequency hydro-generator.

[0104] 43) Height of stator yoke of low frequency hydro-generator;

[0105] When determining the stator yoke height of a low-frequency hydro-generator, the first consideration is that in order to fully utilize the core material and avoid severe saturation of the core material, the design values ​​of the magnetic flux density of each part of the stator and rotor are selected as the magnetic flux density value of the selected core material working in the micro-saturation zone.

[0106] Among them, the magnetic flux density of the stator yoke of the low-frequency hydro-generator is for:

[0107]

[0108] Among them, S ys is the cross-sectional area of ​​the stator yoke of the low-frequency hydro-generator, h ys It is the stator yoke height of low frequency hydro-generator.

[0109] According to step 2), the stator core equivalent length l' and air gap flux density of the low-frequency hydro-generator are determined Combining equations (4) and (9), the stator yoke height h of the low-frequency hydro-generator is determined as ys .

[0110] Finally, the stator outer diameter of the low-frequency hydro-generator is D+2(h ys +h u ).

[0111] 5) Determine the rotor size of the low-frequency hydro-generator;

[0112] The rotor dimensions of the low-frequency hydro-generator include the rotor outer diameter, the rotor salient pole dimensions and the rotor yoke height.

[0113] 51) rotor outer diameter;

[0114] Based on the inner diameter of the stator of the low-frequency hydro-turbine generator, the outer diameter of the rotor of the low-frequency hydro-turbine generator is determined by determining the air gap. By analyzing the magnetic circuit between the stator and rotor of the low-frequency hydro-turbine generator, it can be seen that the larger the air gap length, the larger the excitation current required to generate a certain air gap flux density, and the larger the excitation inductance, which will reduce the power factor of the low-frequency hydro-turbine generator. However, an excessively small air gap length can easily lead to difficulties in assembling the stator and rotor of the low-frequency hydro-turbine generator. During operation, the rotor may experience a bore scraping phenomenon due to slight deformation of the stator and rotor.

[0115] Therefore, in order to meet the power factor requirements of the low-frequency generator and ensure mechanical reliability, the air gap length δ of the low-frequency hydro-generator is proposed to be:

[0116] δ≥(1.2~1.5)(0.001D+1) (10)

[0118] The air gap length δ is determined by formula (10) in mm, and the rotor outer diameter of the low-frequency hydro-generator is obtained as D-2δ.

[0119] 52) Rotor salient pole size of low frequency hydro generator;

[0120] The rotor salient pole dimensions of a low-frequency hydro-generator include pole height and pole width, where the pole height h p It is mainly determined by the number of turns of the excitation winding and the size of the excitation winding, and has a direct impact on the leakage permeability of the magnetic pole. The higher the pole height, the greater the leakage permeability and direct axis transient reactance of the magnetic pole. p for:

[0121] h p =k p τ p (11)

[0122] Among them, k p It is the extreme height coefficient, usually 0.15 to 0.3.

[0123] The pole width is mainly determined by the design value of the magnetic flux density on the salient pole of the low-frequency hydro-generator rotor. According to the design values ​​of the magnetic flux density of each part of the stator and rotor determined in step 4), the pole width b of the salient pole of the low-frequency hydro-generator rotor is determined. p for:

[0124]

[0125] in, is the magnetic flux density on the salient pole of the low-frequency hydro-generator rotor.

[0126] 53) rotor yoke height;

[0127] In order to make full use of the core material and avoid severe saturation of the core material, the design value of the magnetic flux density of the rotor yoke of the low-frequency hydro-generator is selected as the magnetic flux density value of the selected core material working in the micro-saturation zone.

[0128] Magnetic flux density of rotor yoke of low frequency hydro-generator for:

[0129]

[0130] Among them, S yr is the cross-sectional area of ​​the rotor yoke of the low-frequency hydro-generator, h yr is the height of the rotor yoke of the low-frequency hydro-generator, is the peak value of magnetic flux.

[0131] Based on the air gap flux density of the low-frequency hydro-generator determined in step 2) Get the peak flux per level Combined with the equivalent length l' of the stator core of the low-frequency hydro-generator and the design value of the magnetic flux density of the rotor yoke of the low-frequency hydro-generator, Determine the rotor yoke height h of the low-frequency hydro-generator yr .

[0132] Finally, the inner diameter of the rotor of the low-frequency hydro-generator is D-2(δ+h p +h yr ).

[0133] 6) Determine the number of turns of the field winding on the rotor salient poles;

[0134] Finally determine the number of turns N of the excitation winding on the salient pole of the low-frequency hydro-generator rotor f for:

[0135]

[0136] Among them, I f0 is the excitation current of the low-frequency hydro-generator, μ0 is the air magnetic permeability, 4π×10 -7 T·m / A, δ is the equivalent length of the air gap of the low-frequency hydro-generator.

[0137] In the determined low-frequency hydro-generator air gap length δ and air gap flux density peak Based on the rated excitation current or the current density requirement on the excitation winding, determine the number of turns N of the excitation winding of the low-frequency hydro-generator. f .

[0138] Complete the basic electromagnetic design of low-frequency hydro-generator, including design schemes under various combinations of D and l′.

[0139] 7) Electromagnetic simulation verification and solution optimization;

[0140] Establish an electromagnetic simulation verification model for low-frequency hydro-generators, and conduct simulation verification and optimization of the basic electromagnetic design of low-frequency hydro-generators under various combinations of D and l′;

[0141] The process of step 7) is:

[0142] First, observe whether the motor can output low-frequency alternating current, and then observe the electromagnetic verification results. When there is no saturation phenomenon on the stator core and the rotor core, it proves that the sizes of the stator and rotor parts of the designed low-frequency hydro-generator are reasonable. Otherwise, the saturated part needs to be redesigned.

[0143] Finally, the electrical parameters of the low-frequency hydro-generator are observed, and the electrical parameters include the direct-axis and quadrature-axis synchronous inductances. When the electrical parameters meet the design requirements, the electromagnetic design can be completed. Otherwise, the electromagnetic design parameters of the low-frequency hydro-generator are corrected until the electrical parameters meet the design requirements.

[0144] The main results of the final low-frequency hydro-generator electromagnetic design are shown in Table 1:

[0145] Table 1

[0146] parameter unit Design value Stator inner diameter D m Stator equivalent length l' m Number of series turns of each phase of stator winding Ns Turn Number of stator slots Qs indivual Number of parallel branches strip <![CDATA[Stator slot width b u > m <![CDATA[Stator slot height h u > m <![CDATA[Stator yoke height h ys > m Stator outer diameter m Rotor outer diameter m <![CDATA[Width b of rotor pole body p > m <![CDATA[Height h of rotor pole p > m <![CDATA[Height h of rotor yoke yr > m Rotor inner diameter m <![CDATA[Number of turns N of the exciting winding f > Turn Direct axis synchronous inductor H Quadrature-axis synchronous inductor H

[0147] Embodiment 2

[0148] Based on the theoretical calculation of electromagnetic design, the rated parameters of the generator are different, and the design values ​​of the electromagnetic design of the corresponding generator are also different, but the electromagnetic design method is the same. It is better to select a low-frequency hydro-generator with a rated power of 600MW, a rated voltage of 20kV, a rated power factor of 0.9, a rated speed of 100rpm, and a rated frequency of 50 / 3Hz for electromagnetic design. According to the normal range of the per-unit value of the direct-axis and quadrature-axis synchronous reactance parameters of the hydro-generator, which are (0.6-1.5) and (0.4-1.0), respectively, under the rated parameters of this electromagnetic design, the normal ranges of the corresponding direct-axis and quadrature-axis synchronous inductances are calculated to be (0.0034-0.0086)H and (0.0023-0.0057)H, respectively.

[0149] First determine that the pole pair number p of the low-frequency hydro-generator is 10.

[0150] In order to determine the main dimensions of the low-frequency hydro-generator, it is assumed that this design adopts full air cooling. Referring to a 600MW industrial frequency hydro-generator, the electrical load A and magnetic load are selected. The design values ​​are 85900A / m and 1T respectively. According to formula (2), the inner diameter D of the stator of the low-frequency hydro-generator is selected as 15m, and the stator equivalent length l' is taken into account with a certain margin, which is 3.6m.

[0151] Determine the magnetic load, that is, the air gap flux density, to be 1T. Under the rated voltage of 20kV, take the no-load electromotive force as the rated voltage. According to formula (3), the number of series turns of each phase of the stator winding of the low-frequency hydro-generator is 28.87, and the final number of turns is rounded to 30.

[0152] According to the rated power, rated voltage and rated power factor, the rated current I of the low-frequency hydro-generator is obtained. s 19245A, tentatively I u The slot current is 6500A. According to formula (6), the number of stator slots Q of the low-frequency hydro-generator is obtained: s It is 532.93, and the initial design is 534 after rounding. In formula (5), the number of parallel branches a is taken as 3, then the number of conductors per slot Z is 1.0112, which is rounded to 1. At this time, it is necessary to readjust the number of slots according to the number of conductors per slot Z = 1 to obtain the number of stator slots Q of the low-frequency hydro-generator. s The slot current is 540, and the re-verification is 6415A, which meets the value requirements. Therefore, through electromagnetic design, the number of stator slots of the low-frequency hydro-generator is Q s The final design is 540, and the number of parallel branches is 3.

[0153] The number of stator slots is 540, and the inner diameter of the stator is 15 m. It can be seen that the stator slot pitch is 0.0873 m. Therefore, according to formula (7), the stator slot width is taken as 0.025 m, and then the stator slot height is determined to be 0.15 m by formula (8).

[0154] Before determining the height of the stator yoke, the materials of the stator core and the rotor core are determined first. In this embodiment, the materials of the stator core and the rotor core are both DW540_50. According to the magnetization curve of DW540_50, the stator yoke magnetic flux of the low-frequency hydro-turbine generator is designed to be 1T. According to formula (9), the stator yoke height is 0.75m. Considering the armature reaction of the low-frequency hydro-turbine generator under load, a certain design margin is taken, that is, the stator yoke height of the low-frequency hydro-turbine generator is finally designed to be 0.96m. Since the margin of the stator yoke height only affects the saturation degree of the stator yoke magnetic flux density, it does not affect the rotor magnetic flux distribution, nor does it affect the output frequency, output voltage, inductance and other electrical quantities. Therefore, the design margin can be adjusted according to the subsequent magnetic flux density simulation verification results. The larger the margin, the lower the magnetic flux density. The final stator outer diameter is 17.22m.

[0155] The air gap length requirement of the low-frequency hydro-turbine generator is ≥ (19.2~24) mm. The air gap length δ of the low-frequency hydro-turbine generator is taken as 31 mm in this electromagnetic design, so the rotor outer diameter of the low-frequency hydro-turbine generator is 14.938 m.

[0156] In the design of the rotor salient pole of the low-frequency hydro-turbine generator, the magnetic flux density on the rotor salient pole is initially designed to be 1T. According to formula (12), the pole width of the rotor salient pole is greater than 0.75m to meet the magnetic flux density requirement. The pole pitch of the motor is 2.3562m. When the pole width of the rotor salient pole is slightly greater than 0.75m, a larger air gap will be left between adjacent salient poles, which will increase the leakage inductance of the generator and reduce the sinusoidal degree of the air gap magnetic flux in space. In order to reduce the leakage reactance of the low-frequency hydro-turbine generator and make full use of the pole shoe design to make the air gap magnetic field waveform more sinusoidal, the pole width b of the low-frequency hydro-turbine generator is reduced to 1T. p The design is 1.335m. Considering formula (11), take the pole height h p It is 0.404m.

[0157] Determine the rotor yoke height of the low-frequency hydro-turbine generator. According to formula (13), it can be known that the rotor yoke height is greater than 0.75m. In addition to electromagnetic design, the actual hydro-turbine generator may need to consider the inertia support of the unit, that is, to increase the mass of the rotor. In this embodiment, the rotor yoke height of the low-frequency hydro-turbine generator is 2.25m. Similarly, since the margin of the rotor yoke height only affects the saturation degree of the rotor yoke magnetic flux density, it does not affect the stator magnetic flux distribution, nor does it affect the output frequency, output voltage, inductance and other electrical quantities. Therefore, the design margin can be adjusted according to the subsequent magnetic flux density simulation verification results combined with actual needs. The larger the margin, the lower the magnetic flux density, and the larger the rotor mass. The final rotor inner diameter is determined to be 9.63m.

[0158] In this embodiment, in the electromagnetic design of the low-frequency hydro-turbine generator, the winding material is copper. In the design of the number of turns of the excitation winding, the rated excitation current is taken as 1555A. According to formula (14), the number of turns of the excitation winding of the low-frequency hydro-turbine generator can be obtained as 15.86. Finally, the number of turns of the excitation winding of the low-frequency hydro-turbine generator is designed to be 17.

[0159] The finite element simulation software was used to simulate and analyze the low-frequency hydro-generator with a rated frequency of 50 / 3Hz, and the industrial frequency hydro-generator with a rated frequency of 50Hz was used as a comparison. The simulation schematic diagrams of the two are shown in the figure. Figure 3a and Figure 3b As shown in the figure, the three-phase back electromotive force output by the low-frequency hydro-generator is as follows: Figure 4 As shown, it can be seen that Figure 3a and Figure 3b The core parts of the generator are not saturated, and Figure 3bThe magnetic flux density near the stator outer diameter part and the rotor inner diameter part of the 50 / 3Hz low-frequency hydro-turbine generator is very low. This is the result after taking a margin for the stator yoke height and the rotor yoke height in the above method, which is in line with expectations. The corresponding margin can be adjusted based on actual needs or material saving considerations. Figure 4 The output three-phase back EMF waveform has a high sinusoidal degree and low harmonic content. The electromagnetic design simulation results of the low-frequency hydro-generator achieve a low-frequency AC output with a frequency of 50 / 3Hz. The A-phase inductance waveform of the low-frequency hydro-generator is shown in the figure below: Figure 5 As shown by Figure 5 It can be obtained that the direct-axis and quadrature-axis synchronous inductances of the low-frequency hydro-turbine generator designed this time are 0.00463H and 0.00347H respectively, both of which meet the design requirements. Therefore, the electromagnetic design of the low-frequency hydro-turbine generator is reasonable and the design goal is achieved.

[0160] In summary, the main results of the electromagnetic design of the 600MW low-frequency hydro-generator are shown in Table 2:

[0161] Table 2

[0162]

[0163]

[0164] Embodiment 3

[0165] refer to Figure 6 The electromagnetic design system of the low-frequency hydro-generator of the present invention comprises:

[0166] A determination module, used for determining the rated parameters of the low-frequency hydro-generator;

[0167] A selection module is used to select the main dimensions of several low-frequency hydro-generators, wherein the main dimensions of the low-frequency hydro-generators include the stator inner diameter D and the equivalent length l' of the stator core;

[0168] A calculation module is used to calculate the number of stator winding turns corresponding to the main dimensions of each low-frequency hydro-generator, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles, so as to form several electromagnetic design schemes of the low-frequency hydro-generator;

[0169] The simulation module is used to simulate and verify the electromagnetic design schemes of various low-frequency hydro-generators according to the rated parameters of the low-frequency hydro-generators by using the electromagnetic simulation verification model of the low-frequency hydro-generators, obtain the electrical parameters of the electromagnetic design schemes of various low-frequency hydro-generators, and output the electromagnetic design schemes of the low-frequency hydro-generators that meet the preset electrical parameter requirements as the final design results.

[0170] As an implementation scheme of the present invention, the stator inner diameter D and the equivalent length l' of the stator core in the electromagnetic design scheme of the low-frequency hydro-generator satisfy:

[0171]

[0172] Among them, S i is the rated capacity of the low-frequency hydro-generator, n mec is the mechanical speed, k ω is the winding factor, A is the line current density, is the air gap flux density, l′ is the equivalent length of the stator core, and D is the inner diameter of the stator.

[0173] As an implementation scheme of the present invention, the number of turns N of the stator winding is determined according to formula (3): s :

[0174]

[0175] Where ω is the electrical angular velocity, E f The stator winding generates back electromotive force in the magnetic field. is the peak value of magnetic flux per pole, for:

[0176]

[0177] Where, l′ is the equivalent length of the stator core, τ p is the motor pole pitch, It is the average value of the magnetic flux density generated by one pole in the air gap.

[0178] As an implementation scheme of the present invention, the rated parameters of the low-frequency hydro-generator include the rated power, rated voltage, rated speed and rated frequency of the low-frequency hydro-generator;

[0179] The stator dimensions of the low-frequency hydro-generator include the number of stator slots, the stator slot dimensions and the height of the stator yoke;

[0180] The rotor dimensions of the low-frequency hydro-generator include rotor outer diameter, rotor salient pole dimensions and rotor yoke height.

[0181] The division of modules in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, each functional module in each embodiment of the present application may be integrated into a processor, or may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated modules may be implemented in the form of hardware or in the form of software functional modules.

[0182] Embodiment 4

[0183] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the electromagnetic design method of a low-frequency hydro-turbine generator when executing the computer program, for example, comprising: determining the rated parameters of the low-frequency hydro-turbine generator; selecting the main dimensions of several low-frequency hydro-turbine generators, wherein the main dimensions of the low-frequency hydro-turbine generators include the stator inner diameter D and the equivalent length l' of the stator core; calculating the number of stator winding turns, the stator size of the low-frequency hydro-turbine generator, the rotor size of the low-frequency hydro-turbine generator and the number of excitation winding turns on the rotor salient poles corresponding to the main dimensions of each low-frequency hydro-turbine generator, so as to form several electromagnetic design schemes of the low-frequency hydro-turbine generator; according to the rated parameters of the low-frequency hydro-turbine generator, using the electromagnetic simulation verification model of the low-frequency hydro-turbine generator, simulating and verifying the electromagnetic design schemes of each low-frequency hydro-turbine generator, obtaining the electrical parameters of the electromagnetic design schemes of each low-frequency hydro-turbine generator, and taking the electromagnetic design scheme of the low-frequency hydro-turbine generator that meets the preset electrical parameter requirements as the final design result and outputting it. The memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc. The processor, network interface, and memory are interconnected through an internal bus, and the internal bus may be an industrial standard architecture bus, a peripheral component interconnection standard bus, an extended industrial standard architecture bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the program may include a program code, and the program code includes computer operation instructions. The memory may include a memory and a non-volatile memory, and provide instructions and data to the processor.

[0184] Embodiment 5

[0185] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of implementing the electromagnetic design method of a low-frequency hydro-generator are, for example, including: determining the rated parameters of the low-frequency hydro-generator; selecting the main dimensions of several low-frequency hydro-generators, wherein the main dimensions of the low-frequency hydro-generators include the stator inner diameter D and the equivalent length l' of the stator core; calculating the number of stator winding turns, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator, and the number of excitation winding turns on the rotor salient poles corresponding to the main dimensions of each low-frequency hydro-generator, so as to form several electromagnetic design schemes of the low-frequency hydro-generator; according to the rated parameters of the low-frequency hydro-generator, using the electromagnetic simulation verification model of the low-frequency hydro-generator, simulating and verifying the electromagnetic design schemes of each low-frequency hydro-generator, obtaining the electrical parameters of the electromagnetic design schemes of each low-frequency hydro-generator, and outputting the electromagnetic design schemes of the low-frequency hydro-generator that meet the preset electrical parameter requirements as the final design results. Specifically, the computer-readable storage medium includes, but is not limited to, for example, volatile memory and / or non-volatile memory. The volatile memory may include a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include a read-only memory (ROM), a hard disk, a flash memory, an optical disk, a magnetic disk, etc.

[0186] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0187] The present application is described with reference to the flowchart and / or block diagram of the method, device (system) and computer program product according to the embodiment of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, and the combination of the process and / or box in the flowchart and / or block diagram can be realized by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for realizing the function specified in one process or multiple processes in the flowchart and / or one box or multiple boxes in the block diagram.

[0188] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0189] These computer program instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0190] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A low-frequency hydro-generator electromagnetic design method, characterized in that: include: Determine the rated parameters of low-frequency hydro-generators; Selecting main dimensions of several low-frequency hydro-generators, wherein the main dimensions of the low-frequency hydro-generators include the stator inner diameter D and the equivalent length l' of the stator core; Calculate the number of stator winding turns corresponding to the main dimensions of each low-frequency hydro-generator, the stator dimensions of the low-frequency hydro-generator, the rotor dimensions of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles, so as to form several electromagnetic design schemes for the low-frequency hydro-generator; According to the rated parameters of the low-frequency hydro-generator, the electromagnetic simulation verification model of the low-frequency hydro-generator is used to simulate and verify the electromagnetic design schemes of each low-frequency hydro-generator, and the electrical parameters of each electromagnetic design scheme of the low-frequency hydro-generator are obtained. The electromagnetic design scheme of the low-frequency hydro-generator that meets the preset electrical parameter requirements is taken as the final design result and output.

2. The electromagnetic design method of a low-frequency hydro-generator according to claim 1, characterized in that: The stator inner diameter D and the equivalent length l' of the stator core in the electromagnetic design of the low-frequency hydro-generator satisfy: Among them, S i is the rated capacity of the low-frequency hydro-generator, n mec is the mechanical speed, k ω is the winding factor, A is the line current density, is the air gap flux density.

3. The electromagnetic design method of a low-frequency hydro-generator according to claim 1, characterized in that: According to formula (3), the number of stator winding turns N is determined s : Where ω is the electrical angular velocity, E f The stator winding generates back electromotive force in the magnetic field. is the peak value of magnetic flux per pole, for: Among them, τ p is the motor pole pitch, It is the average value of the magnetic flux density generated by one pole in the air gap.

4. The electromagnetic design method of a low-frequency hydro-generator according to claim 1, characterized in that: The rated parameters of the low-frequency hydro-generator include the rated power, rated voltage, rated speed and rated frequency of the low-frequency hydro-generator; The stator dimensions of the low-frequency hydro-generator include the number of stator slots, the stator slot dimensions and the height of the stator yoke; The rotor dimensions of the low-frequency hydro-generator include rotor outer diameter, rotor salient pole dimensions and rotor yoke height.

5. A low-frequency hydro-generator electromagnetic design method, characterized in that: include: A determination module, used for determining the rated parameters of the low-frequency hydro-generator; A selection module is used to select the main dimensions of several low-frequency hydro-generators, wherein the main dimensions of the low-frequency hydro-generators include the stator inner diameter D and the equivalent length l' of the stator core; A calculation module is used to calculate the number of stator winding turns corresponding to the main dimensions of each low-frequency hydro-generator, the stator size of the low-frequency hydro-generator, the rotor size of the low-frequency hydro-generator and the number of excitation winding turns on the rotor salient poles, so as to form several electromagnetic design schemes of the low-frequency hydro-generator; The simulation module is used to simulate and verify the electromagnetic design schemes of various low-frequency hydro-generators according to the rated parameters of the low-frequency hydro-generators by using the electromagnetic simulation verification model of the low-frequency hydro-generators, obtain the electrical parameters of the electromagnetic design schemes of various low-frequency hydro-generators, and output the electromagnetic design schemes of the low-frequency hydro-generators that meet the preset electrical parameter requirements as the final design results.

6. The low-frequency hydro-generator electromagnetic design system according to claim 5, characterized in that: The stator inner diameter D and the equivalent length l' of the stator core in the electromagnetic design of the low-frequency hydro-generator satisfy: Among them, S i is the rated capacity of the low-frequency hydro-generator, n mec is the mechanical speed, k ω is the winding factor, A is the line current density, is the air gap flux density.

7. The low-frequency hydro-generator electromagnetic design system according to claim 5, characterized in that: According to formula (3), the number of turns N of the stator winding is determined: s : Where ω is the electrical angular velocity, E f The stator winding generates back electromotive force in the magnetic field. is the peak value of magnetic flux per pole, for: Among them, τ p is the motor pole pitch, It is the average value of the magnetic flux density generated by one pole in the air gap.

8. The electromagnetic design system for low-frequency hydro-generator according to claim 5, characterized in that: The rated parameters of the low-frequency hydro-generator include the rated power, rated voltage, rated speed and rated frequency of the low-frequency hydro-generator; The stator dimensions of the low-frequency hydro-generator include the number of stator slots, the stator slot dimensions and the height of the stator yoke; The rotor dimensions of the low-frequency hydro-generator include rotor outer diameter, rotor salient pole dimensions and rotor yoke height.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the low-frequency hydro-generator electromagnetic design method as described in any one of claims 1 to 4 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the low-frequency hydro-generator electromagnetic design method as claimed in any one of claims 1 to 4 are implemented.

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