Dongfang Electric Review 3, 500061730 Hydrogenerator Dongfeng Motor Factory Luo Zhonghua Yin Shanlin 1 Foreword Guankou Power Station uses the high-speed large-capacity horizontal hydro-generator unit produced by Dongfeng Motor Factory earlier. With the increase of similar unit ordering contracts and the increasing experience in design and manufacturing in recent years, Dongfeng Motor Factory has mastered and improved the design and manufacturing technology of similar units. The design and manufacturing characteristics of this type of unit are mainly the structural design and manufacturing methods of the solid magnetic pole; the particularity of the solid magnetic pole electromagnetic calculation method; the control of the bearing temperature of the bearing with large load; the suppression of vibration and noise of the high-speed unit.
2 generator basic data model rated power rated voltage kg rated current A rated power factor rated frequency + fc rated speed r.min1 flying speed r.min1 receiving date 210628 3 design features 3.1 electromagnetic design in electromagnetic calculation, for this The particularity of the unit, after a number of comparisons, yielded a better electromagnetic solution. In the choice of electromagnetic scheme, the following aspects are considered.
Due to the high flying speed, the rotor must have a solid magnetic pole structure. The solid magnetic pole itself has a strong damping effect, so the damper winding is no longer added, which simplifies the rotor structure and enhances the ability to withstand higher mechanical stresses.
The number of slots per phase per pole of the stator is integer +1. Since there is no conventional damping structure, the secondary tooth harmonics can be effectively reduced, and the large voltage waveform distortion that may occur after using the integer slot can be avoided, thereby ensuring the generator. Power generation quality.
After the rotor adopts the solid magnetic pole structure, the pole surface loss is reduced to the magnetic pole, and the stator slot width and the air gap 5 ratio are preferably less than 1. The Ge air gap 5 should be biased to a large value to reduce electromagnetic vibration and noise, so that the unit Overall performance is better. So even if the short circuit is larger, it is beneficial to use more copper.
A split pole piece with a lower body density and better heat dissipation. Between the separated pole piece block and the pole body, a dimensioned groove is formed along the axial direction outside the magnetic pole to increase the equivalent air gap and the heat dissipation surface, and the partial heat of the pole shoe surface can be effectively prevented.
The generator adopts a flat-plate propeller fan with high axial efficiency and high efficiency, and forms a radial axial double-path ventilation system with axial ventilation.
Take a closed self-circulating air cooler cooling method. 3.2 Structural design The generator adopts the horizontal axis two-point structure. The structure is a better type of structure developed in recent years. Because the turbine runner is directly connected with the generator main shaft, the structure is compact, the land occupation is small, the installation and debugging are convenient, and the underground workshop can be well satisfied. limit. However, since the flying speed of the unit is 179, and the flying speed of the critical speed of not less than 1.2 times is required to adopt two fulcrum points, the force of the shafting system changes greatly, which is less fulcrum, and the overhanging end of the shaft is increased. The load and the critical speed are greatly reduced. By adjusting the distance between the fulcrums and the journal diameter, the unit's critical speed requirements are met.
In order to meet the safety and reliability of the unit under the flying condition, the stress of the rotating parts must be strictly controlled. Since the centrifugal force coefficient of the unit is up to 36 times in the flying condition, the conventional magnetic pole structure is difficult to meet the requirements, and the comb-tooth structure introduced in some design materials has high stress values ​​of related parts, and must be adopted. Tensile strength alloy steel, and the structure is not ideal, can not be directly applied. In order to solve this problem, a more reasonable comb-shaped solid magnetic pole structure is proposed, which not only reduces the stress of related parts, but also has low requirements on materials and the processing amount is also reduced. Concrete structure 2.
It can be seen from 2 that the solid magnetic pole is forged from the shaft of the shaft, and the pole piece of the fixed excitation winding is formed as a separate pole piece, which is embedded in the corresponding slot of the pole body to form a comb shape and pass The steel pin fastens it to the pole body, which minimizes the quality of the separating parts and reduces the centrifugal force of the separating parts, thereby controlling the stresses of the relevant components under flying conditions. At the same time, the structure of the dangerous section is more reasonable than that of the magnetic pole. The following are the stress values ​​of the dangerous section under the flying condition of the relevant components. The steel pin shear stress 61 pole piece bending stress 220 end shear stress 65 end bending stress 268 due to the large generator capacity, used in higher heads and The large-flow matching turbine makes the generator bearing need to bear large water thrust and radial force. Thus, the bearing load factor scale = 12 is large, up to 265, and its heat generation and required cooling cycle oil volume are large. In the design of radial thrust bearings, the first use of parallel loops with internal and external circulation is also very different.
4 Process measures According to the structural characteristics of the unit and the accuracy of the parts, 24 sets of tooling molds are designed and manufactured. Only the metal parts of the product parts and the tooling for the electric machining process are used. The professional process molds such as welding, stamping, casting and forging are not included to ensure the thrust tile stator. Important parts on the coil rotor, etc. 4.1 Finishing and milling fixture control thrust tile thickness design paper requires that each thrust tile thickness difference is controlled within 0.,1, the process uses a tile blank round machining and casting alloy, milling after finishing Cut into pieces, and then fix 10 thrust pads at the same time by milling cutters on the bed. Milling the tile alloy surface to ensure that the thickness difference of each thrust tile is within the paper requirements.
4.2 Manually assisted drawing to form the stator wire, the axial length of the stator coil exceeds 1600, the span exceeds 560, and the maximum drawing span of the drawing machine has been exceeded.
In the specific operation, manual assisted drawing and final replication to paper requirements were employed.
4.3 Difficulties in the processing of main parts of the rotor Due to the high capacity and high speed of the unit, the rotor adopts a magnetic pole body and a rotating shaft forging into a body pole piece and a pin body structure fixed by a pin. The structure has high strength and can withstand high working stress, but the processing precision of the parts has high rotor assembly precision, the corresponding processing cycle is long, and the unit manufacturing cost is also high. Difficulties in machining are mainly reflected in the 6-pole pole-cutting pole block combination turning in the shaft shaft of the shaft. 18 into 530 deep pin hole drilling size thrust ring hot-rolling behind the shaft grinding the magnetic pole coil on the shaft to simulate the rapid running centrifugal force The insulation withstand voltage test and the overspeed test of the rotor after the total assembly in the factory.
4.3.1 The coarse and fine planing shaft and the precision car's pole shaft are extremely long in the axial direction of about 1200. Only the machining of the body requires the iron filings to be scraped down, so the machining cycle on the machine is long. Due to the large amount of cutting, in order to avoid the residual stress exceeding the standard after finishing, the roughing planing on the gantry planer, the artificial aging semi-finishing vehicle, the artificial aging and the fine planing and the finishing of the arc groove of the fine shoe are adopted. Processing 6 magnetic poles.
4.3.2 Combination of pole shoe blocks Each pole has 16 pole pieces, which are fitted in the arc of the shaft and fixed by pins. The six poles are 96 pieces.
In order to ensure the tightness of the assembly of all pole pieces and the outer circle of the pole piece, increase the reliability of the unit operation and reduce the voltage distortion caused by the manufacturing. 48 pieces of the sub-clamping by the fixture are adopted, and the corresponding arc on the rotating shaft The pole pieces are machined in a way.
4.3.3 pole shoe block and pole with the same drill hole, each pole has 3 pin holes, 6 poles total 18, the hole axial depth is more than 1000. Considering the spindle lying on the trampoline processing 18 pin holes to find The trouble and the need to add the deflection of the slender pin will cause the centerline of the hole to be skewed too much, and the ellipticity of the hole is not easily guaranteed. In actual production, firstly, the set of pole pieces of the magnetic poles are fixed on the shaft pole of the shaft by the drill jig, then the hanging spindle is placed vertically in the pit at the rocker drilling machine to find the vertical, and the shaft end flange is pressed by the pressing plate, The rough drill divides each hole several times to meet the paper requirements. Special equipment is used in the drilling process, which effectively solves the problem of tool cooling and iron removal in deep hole machining.
Through the complexing of the holes of each group, the straightness of the ellipticity of the hole and the position of the entrance and exit holes have reached the design value, which is beneficial to the assembly and disassembly of the process pin during the coil test and the reliable tightening of the product pin during the rotor assembly. 4.3.4 Magnetic pole The coil manufacturing and the inter-pressure withstand test are based on a high-speed unit. In order to control the mutual difference of the magnetic pole coils within 28, a coil-type flat winding coil is used. When the winding, the copper row is properly pressed by the splint device, and the internal force of the copper bar is controlled by the weight force measuring device, and the copper bar is wound around the core to make it close to the core, and the height of the coil and the inner frame size are reliably controlled. It effectively ensures that the total amount of coils is within the tolerance.
Because the magnetic pole body and the rotating shaft are forged, the magnetic pole coil inter-turn voltage withstand test cannot be applied according to the centrifugal force of the conventional unit on the hydraulic press directly simulating the operation of the unit, but the magnetic pole coil is correspondingly placed on the pole body, and is used for wearing the test. After the pin is pressed, it is pressed by the pressing tool for the inter-turn insulation withstand voltage test.
4.3.5 Rotor assembly and dynamic balance and over-speed test In order to reduce the uneven distribution of the circumferential mass caused by the assembly of the magnetic pole coil, the coil should be tightly weighted and assembled on the shaft of the shaft before assembly, and the pin is inserted into the product pin. The pressure between the pole piece and the pole coil is measured by a special measuring tool, and the pressure is adjusted by appropriately increasing or decreasing the insulating gasket. After the rotor is assembled, the upper balancing machine is tested. It is required to be hung on the overspeed machine and tested at 1.8 times the rated speed. After strict inspection, after re-tightening, reassemble all the assembly screws.
5 Conclusion 6730 is the first rotor magnetic comb structure unit produced by Dongfeng Motor Factory. No matter the design process or the production difficulty, it is the first of all kinds of hydro-generator units produced by the factory. of. Therefore, the plant has made sufficient arrangements in terms of manpower and material technology and production since the start of production, so that the secondary operation of the power station is successful. The successful operation of the unit has laid a solid foundation for improving the strength of the plant.
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