The first QFR-15-2 gas turbine generator developed by HEC is a matching unit of QD-128 gas turbine generator set of an aviation enterprise. This paper introduces the special technical requirements, structural characteristics and difficulties in the design of gas turbine generators.
Gas turbine generators; supporting units; technical points 1 Introduction In today's international market, the large capacity of gas turbines has promoted the development of combined cycle power plants. The most important feature of combined cycle power plants is that the total thermal efficiency can reach more than 55%, than conventional The thermal power station is nearly 20% higher. The combined cycle power plant includes a gas turbine generator driven by a gas turbine and a steam turbine generator driven by a waste heat boiler-steam turbine. The development of power environmental protection technology, resource economy and grid demand make gas turbine generator sets with small size, high efficiency, flexible installation location and environmental protection features more and more widely used. Such as joint cycle green environmental power station, fast-install small mobile power station.
The gas turbine generator set is composed of a gas turbine device as a driving portion and a generator device as a part for producing electric energy. The speed of the compressor in the gas turbine is 13000r/min, and the speed of the power turbine is 4700. 4.3 Induction Heating Method The induction heating method is realized by the resistance heat of the induced current generated by the weldment in the alternating magnetic field. This method is one of the most commonly used heating methods for the parallel welding of stator bars of large and medium-sized hydroelectric generators.
Foreign ABB companies, ALSTOM companies and domestic Harbin companies are adopting. With this method, regardless of whether the generator stator bars are joined by a lap joint structure, a docking structure or a duplex structure, heating brazing can be achieved as long as a certain space is provided.
The induction coil is an important component of the induction brazing equipment, through which the energy of the AC power source is transmitted to the weldment. According to the different structure of the parallel head, the induction coil can be designed into various types. Generally, the induction coil is similar to the shape of the weldment. In order to improve the heating efficiency, the induction coil is more closely coupled with the workpiece to be welded.
Induction heating often requires some auxiliary tools to clamp and position the weldment to ensure assembly accuracy and relative position to the induction coil, and to improve productivity and ensure brazing quality.
The induction heating method uses the induction heating method to have a large technical content. Compared with the above two methods, the price of the equipment is high, and the maintenance personnel need a high level.
5 Conclusion The design of the stator bar of the hydro-generator and the selection of the brazing heating method are complementary. The design of the head structure should first ensure the size of the head overlap or the cross-sectional dimension of the joint, and then According to the process technology level and process equipment status of the manufacturer, the final purpose of the design of the generator stator bar and the selection of the brazing heating method is to obtain a good brazed joint to provide high quality to the user. The product.
Hu Yitong (959-) graduated from the Workers University of Harbin Electric Machinery Factory in 1984. He is currently engaged in brazing work and engineers. R7min, and then decelerated to 3000r7min through the gearbox and connected with the generator. Gas turbine generators and turbo generators are classified as turbine type synchronous motors, but they are characterized by the installation and operation modes of gas turbines, auxiliary engines and power stations, and some abnormal operating conditions of turbo generators are in gas turbines. Operation is also a regular requirement, which determines a lot of special features in the structure. In HEC, QFR-15-2 gas turbine generators are fully prepared for the development of larger capacity gas turbines as a prototype of the combined cycle.
Technical data Rated capacity Rated power Rated voltage Rated current Power factor Rated frequency Rated speed Structure design The generator is a hidden pole generator. Its prime mover is a gas turbine, which adopts coaxial brushless excitation and the cooling mode is closed air circulation cooling.
The basic structure of the 10715-2 turbo generator design, combined with the absorption of modern advanced design technology, is relatively advanced and reliable from the motor performance to the structure.
3.1 Stator structure Since the gas turbine generator does not have the basic air path of the conventional air-cooled steam turbine generator, the generator must have the characteristics of small size and compact structure to meet the requirements of convenient and flexible installation of the unit. Therefore, the machine adopts a square base and a cooler overhead structure. Use IDEAS 3D design in the design to make full use of the space and arrange the air duct. The ventilation method is one in and two out (see).
The stator core is made of a low-consumption oriented silicon steel sheet, which is divided into 40 core segments, and 39 radial cooling air passages are formed between the core segments by ventilation channels.
The stator coil is a strip bar, and the double glass wire is divided into two rows. It is replaced by 360 Robel and embedded in 54 slots. The insulation between the rows is epoxy multi-mica mica tape with anti-halation layer. Multi-glue insulated wire rods do not need to be molded, and are outsourced with less tape. After the lower wire, the stator vacuum is fully immersed in epoxy solventless paint, that is, F-class VPI insulation. The insulation structure has excellent electrical and mechanical properties, and reduces the temperature of the stator core and the winding. l is very beneficial. The nose end welding of the wire rod replaces the common welding of the other units by the sealing welding process, thereby greatly improving the production efficiency. In order to facilitate the installation of the neutral point cabinet, the stator lead wire is led out laterally, and in order to ensure a reasonable internal and external interface size, the 3.2 rotor structure generator rotor is made of high-strength alloy steel 25Cr2N14MoV forging, in the rotor body and protection A crescent-shaped auxiliary ventilation groove is formed in the large tooth portion of the ring lap to improve the heat dissipation effect at the end of the rotor. In order to improve the ventilation and cooling of the end of the rotor winding, the ventilating hole structure (44 in total) on each small tooth of the rotor is used to replace the small tooth open crescent pin nail structure to overcome the disadvantages of the end groove deformation and facilitate the lower line. After the grooved wedge improves the processability, the improved vent structure, see.
The venting hole is located at the joint of the rotor tooth and the retaining ring, and the stress state of the material is relatively complicated. For this reason, the finite element method and the IDEAS program are used to calculate the stress of the structure: calculation working condition: rated speed running speed: 3000/nin Centrifugal force of all objects in one slot: 1038.bN/mm Coupling length of the retaining ring and the body: 35mm retaining ring and body mating force: 9.06E+ 5N vent hole diameter: 17mm normal working, the main stress of the rotor tooth is as follows : 0MPa Ventilation hole stress: 227. 0MPa rotor body mating end stress: 50.0MPa The above stress calculation results show that after the rotor teeth open the vent hole, the stress level is not high, fully meet the strength requirements.
Since the operation requirement of the generator is not less than 500 times and 100% peaking, the rotor winding is changed from the soft flat copper wire wound structure commonly used by conventional small steam turbine generators to the cold drawn silver-containing copper wire. Semi-welded structure to improve its creep resistance. The rotor winding is connected with the exciter through the conductive rod of the conductive screw, and has the characteristics of simple and reliable structure. In this structure, the conductive screw has a fan-shaped boss, and the steel pressure cap is used to bear the self-weight caused by the conductive screw and the conductive piece when the rotor rotates. The centrifugal force avoids the stress at the joint between the conductive screw and the conductive rod, and also helps to relieve the bending stress of the conductive rod on the conductive rod. The conductive sheet adopts a special flexible structure to adapt to the operation under low cycle fatigue. The insulating structure is vacuum-impregnated with a polyester glass ribbon wrapped around it, then dried, and finally the surface is coated with 9120 epoxy dry paint.
The rotor retaining ring is made of non-magnetic forged steel 50Mn18Ci5 to protect the winding ends. The outer diameter of the grommet is reduced by intensity calculation and is at an angle of 15 near the body (see).
The gap between the large retaining ring and the core effectively solves the local overheating caused by the no-load surface loss and the pulse vibration loss caused by the core slot.
This is a small generator with a relatively small gap between the guard ring and the core. In particular, the 3.3 exciter QFR-15-2 gas turbine generator is used in the excitation mode, and is equipped with a coaxial small brushless exciter, which is shared with the generator. One shaft (no coupling in the middle). The entire rotor of the exciter is suspended from the extension shaft of the generator. The armature winding and the rectifying disc of the exciter are sleeved on the turbine generator shaft, and the rotor winding of the turbo generator is connected with the rectifying plate through the radial conductive screw and the conductive rod in the shaft hole. The stator constitutes the magnetic field of the exciter and the cover rectifying plate and the armature winding of the exciter are all covered inside. The stator base adopts a steel plate welded structure, and the upper magnetic pole is rounded in the base, and the base corresponds to the yoke of the magnetic pole. After the stator and rotor of the exciter are assembled, the upper end cover and the sealing ring are installed at both ends of the stator to form an exciter inlet and outlet air passage. The detection end of the excitation end cap is equipped with a carbon brush and a protective cover for testing.
3.4 Axial Position and Positioning of the Unit The gas turbine unit is connected to the generator through a gearbox from the driving gas turbine. Because the motor is equipped with a chassis, the whole transportation, the power plant is not disassembled and directly placed in the power generation, and the on-site assembly process is cancelled. Therefore, when determining the axial position of the generator, the axial thermal expansion of the rotor when the unit is loaded is considered. In the internal assembly, the magnetic centerline of the rotor is pre-shifted to the drag end with respect to the magnetic centerline of the stator by 1.2~1. 5mm, that is, the magnetic centerline is not centered in the cold state, the hot state is centered, and the thermal expansion preload is completed in the factory. Settings.
Correspondingly, the transport locking device is designed. The air end support and the end plate connect the coupling to the bottom frame to fix the shaft and the radial direction; the excitation end locks the shaft and the bearing seat to fix the radial direction. (see).
These structures can fully guarantee the fixing of the generator rotor during transportation, absorb the impact load during transportation, and play the role of axial installation and positioning.
3.5 bearing structure Conventional steam turbine generator bearing working oil temperature is 45C, while the gas turbine generator bearing starts with the oil temperature is 35C, the normal operating oil temperature is 55 cylindrical bearing bush can not meet the working condition, in severe cases The oil film oscillates and the center of the shaft diameter rotates unsteadily in the bearing, causing the unit to vibrate. The elliptical tile is calculated to meet the requirements of the machine.
Table No. Name Design value Test value Stator winding resistance (75 Â°C), n/phase rotor winding resistance (75 Â°C), n no-load excitation current, A short-circuit excitation current, A rated excitation current, A rated excitation voltage, V Short circuit ratio (Kc) static overload capacity (S) stator basic copper consumption (75 Â° C), kW miscellaneous consumption, kW stator core loss, kW mechanical loss, kW excitation loss kW total loss, kW efficiency, % stator core temperature rise, K stator winding temperature rise, K rotor winding temperature rise, K stator leakage reactance, % zero sequence reactance, % negative sequence reactance, % direct axis synchronous reactance, % straight axis transient reactance, % straight axis super transient reactance, % cross Axial super-transient reactance, %36 overhead straight cooler This machine uses an overhead cooler, which is suitable for the sealing problem. The end cover is equipped with a float type water leakage sensor and a drainage device. In case of accidental water leakage, an alarm is issued in time to take measures to prevent damage to the insulation structure of the generator.
The generator of the generator and the rotor insulation of the generator are all Class F. According to the B-level assessment, the temperature of the cold air outlet of the generator air cooler does not exceed 4C, ensuring that the temperature rise of the stator winding does not exceed 80K. The temperature rise of the rotor winding exceeding 80K does not exceed 90 IK bearing oil temperature does not exceed 65C bearing temperature does not exceed 80C. 4 In-plant type test after the pilot test of the generator in the factory, the design parameters and test results are shown in Table 1. This type The generator design adopted several new structures, and the test results showed that the first machine of the new model met the design requirements.
5 Conclusion The development of QFR-15-2 fills the blank of HEC gas turbine generators and lays a good technical foundation and provides a basis for designing and manufacturing series gas turbine generators in the future.
Yu Song (1972-) graduated from Harbin Institute of Technology in 1995. He graduated from Harbin University of Science and Technology in 1999 with a bachelor's degree in automation. He is currently working in the product design department of Harbin Electric Machinery Co., Ltd.
In 1985, Yiye graduated from Harbin Institute of Electrical Engineering with a major in electrical engineering. He graduated from Harbin Institute of Technology in 1991 with a bachelor's degree in radio engineering. He is currently working as a generator manufacturer.
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