2 Lanzhou Electric Machinery Co., Ltd. 7 30050 Wang Daqing Electromagnetic and structural characteristics of this series of generators.
Descriptor generator brushless excitation phase compound excitation structure 1 Introduction volume production economical convenient long distance transportation. It can also be applied efficiently in all sectors of the national economy and in daily life. The development of the power industry is an important foundation for the development of the national economy. However, the power shortage in some areas is still outstanding, affecting the development of the local economy. In order to solve the power shortage, diesel power stations were established there. The production system of diesel generator sets as electric energy has a small investment and is widely used in self-provided power plant regional power plants or temporary power plants. As an electromechanical energy conversion unit, the performance of the generator directly affects the quality of the power supply. From the current point of view, the excitation system has become the core part of the AC synchronous generator. The quality of the excitation system directly affects the operation quality of the synchronous generator, so all countries are committed to the research and improvement of the excitation system.
The magnetic phase compound excitation system excites the static thyristor rectification excitation brushless system excitation phase. Since the 1960s, industrial developed countries have developed their own series of brushless synchronous generators. Especially high-capacity high-voltage brushless generators.
2 generator working principle armature, when the excitation winding is connected to direct current, a magnetic field is generated in the air gap of the generator. When the prime mover drives the rotor to rotate, there is relative movement between the conductor and the magnetic field in the stator slot, so that the stator conductor is induced. Out of the AC potential. When the potential is taken out, the generator has an electric energy output. There is only one main magnetic field that rotates synchronously in the motor at no load. When the stator winding has current at load, the first magnetic potential appears, so the excitation magnetic potential of the motor can be synthesized by two components, that is, the internal potential is generated, and the required magnetic potential and the load compensate the armature reaction magnetic potential. The magnetic potential, the angle between the two components is å¿2, the simplified phasor is to keep the generator terminal voltage constant, the excitation current must follow the generator load current and the power factor 2 electrical principle 21 high voltage current transformer 2 main generator stator Winding 3 Fundamental Auxiliary Winding 4 Main Generator Field Winding 5 Rotating Rectifier.
6 excitation electromechanical armature around the sister 7 excitation machine excitation winding 8 set resistance 9 static rectifier voltage regulator ruler linear reactor 3 brushless phase compound excitation generator working principle When dragging the generator rotor rotation, the fundamental auxiliary winding cutting host left The magnetic field generates the residual magnetic potential tile, which is applied to the AC input terminal of the stationary phase bridge rectifier via a linear reactor. After rectification, the excitation current in the excitation winding of the AC exciter is established, and the AC exciter magnetic field is established. At this time, the excitation electromechanical armature is coaxial with the host rotor. Induction of the corresponding potential and. After being rectified by the rotary rectifier, it is the excitation current to the main field winding. If the impedance drop of the excitation current in the auxiliary winding is neglected, then the resistance line of the static excitation circuit is correspondingly determined, and when the polarity of the excitation winding connection rectifier is correct, the air gap magnetic field of the main engine and the exciter is enhanced, and correspondingly The load characteristic is generated, and the excitation current 3 is generated correspondingly to the team 1 until the induced DC voltage of the generator fundamental auxiliary winding is rectified, and the voltage drop generated in the static circuit generated by the static excitation circuit is equal to the DC voltage. That is, when the volt-ampere characteristic straight line and the no-load characteristic curve of the fundamental auxiliary winding intersect, the mutual excitation stops, the stability is reached, and the no-load voltage of the generator reaches the rated value. The generator is blocked to determine.
When the generator is loaded, the load current passes through the secondary winding of the high-voltage current transformer, and the output current of the secondary winding is in phase with the load current, and is proportional to the current phasor of the linear reactor that lags behind the voltage 90. The static phase bridge rectifier flows through the excitation winding of the AC exciter, and the corresponding armature current of the AC exciter is rectified by the rotary rectifier and applied to the main excitation winding. With appropriate parameters, the excitation loop system can provide different generators. The excitation electric motor technology 20012 flow required for the load, so that the automatic maintenance voltage is constant within a certain range.
Cut off the setting resistor and connect it to the voltage regulator.
Phase-controlled compound excitation device. When the generator operating conditions change, the generator terminal voltage deviates. At this time, the original uncontrollable phase compound excitation device corrects the deviation, and the ruler corrects the deviation with higher precision through the measurement and comparison links. The adjustment process of the ruler can only be carried out when there is flow separation, that is, the excitation current provided by the uncontrollable excitation system has sufficient shunting margin. When the terminal voltage of the generator increases, the shunt value increases, and the excitation current of the exciter and the host decreases. Thereby the generator terminal voltage remains unchanged. Conversely, when the generator terminal voltage drops, the opposite adjustment is made.
When the generators are operated in parallel, the adjustment section of the six 7 should be connected. The adjustment section will give a voltage signal proportional to the reactive current of the generator. This signal is superimposed with the measurement signal of the generator terminal voltage to make parallel operation. Each of the generators can share the reactive power in a balanced manner.
3 electromagnetic structure characteristics 0 electromagnetic characteristics on the generator, voltage fluctuation rate steady state voltage regulation rate transient voltage regulation rate voltage waveform distortion rate are important indicators to measure the performance of the generator. Due to the magnetic inertia of multiple AC exciters of the brushless generator, the excitation and loop response time becomes longer, and the dynamic performance of the brushless generator deteriorates. In order to improve the performance of the generator, the magnetic tooth density of the stator teeth of the main unit is high. Generally at 16000, 5 or more, the motor works in a state where the magnetic circuit is saturated. From the saturation of the generator, the influence of fluctuations in the excitation power supply on the generator terminal voltage is smaller. In addition, the short-circuit transient reactance of the motor with high magnetic density will become smaller, and the dynamic stability limit will increase. The transient voltage drop and voltage change at the sudden load will be smaller, but the magnetic circuit saturation will cause the rotor excitation capacity. Ascending, the temperature rise of the field winding increases. To this end, the air gap is appropriately reduced to compensate for the rise of the excitation capacity, and the air gap is taken to be about 1.4 of the motor pole, but measures must be taken during design to reduce the higher harmonics due to the reduction of the air gap, especially the teeth. The effect of harmonic increase on the motor waveform.
For the excitation circuit, because of the phase-complex excitation self-excited constant voltage form, the voltage is kept constant under the uncontrollable state, the key is the selection of the electromagnetic parameters of the excitation circuit. As the constant voltage device unit of the excitation circuit, the magnetic density of the reactor and the current transformer is less than 8000, 8, and the reactance value is greater than the temperature rise of the excitation coil winding resistor and the current transformer of the exciter. As an important unit of the excitation circuit, the AC exciter improves the dynamic characteristics of the brushless generator, improves the instantaneous sensitivity of the excitation current of the AC exciter, shortens the time constant of the exciter, and makes its working state in a linear state of magnetic circuit unsaturation. . Generally, the AC excitation electromechanical teeth are magnetically dense at around 700008, the short circuit ratio is less than 0.5, and the frequency is higher than the host frequency. It is worth noting that the number of poles of the AC exciter and the number of poles of the host should not be integer multiples. In addition, when a short circuit fault occurs in the power system or other causes cause the generator terminal voltage to drop seriously, the excitation system must be strongly excited to reduce the attenuation of the generator potential and even increase the potential of the generator, thereby improving the system uniformity. There is a certain inductance, so that the change always lags behind. In order to shorten the hysteresis, the excitation system is required to have a fixed top voltage and voltage growth speed. The above electromagnetic parameters can be matched to meet this requirement.
Structural characteristics The brushless phase compound excitation generator is mainly composed of a host AC exciter rotary rectifier constant voltage excitation device voltage regulator. The stator base of the mainframe is a steel plate welded structure, the stator core is laminated by high-quality silicon steel sheets, the coil is a double-layered laminated winding, and the phase-wave auxiliary winding is arranged in the stator slot, and the winding is made of tinned copper core and 46 insulated wire. The outer insulation is placed in the slot, and the end crosses from the back of the main winding 1 to prevent damage during assembly. 1 The auxiliary winding line voltage is less than 400. The salient pole structure of the main rotor is used to facilitate the selection of the rectifying components and improve the reliability of the components. The number of magnetic pole coils is larger than that of a normal motor to increase the excitation voltage and reduce the excitation current. The rotating armature structure of the AC exciter, the armature is coaxial with the main rotor, the stator is a salient-pole type winding structure, the base is on the same base as the main machine, and the exciter is placed on the outer side of the front bearing. The wave line structure, the rectifying element is radially mounted by compressive stress to improve the reliability of the element in the rotating state. Because the large generator rotor is provided with a damper winding, the exciter is large, so the RC protection unit and the fuse rectifying element and the collector ring silicon-aluminum composite bottom plate 2 rear bearing 3 rotor 4 stator 5 constant voltage device 6 are not provided in the rotary rectifier unit. Rotary rectifier 7 front bearing 8 exciter stator 9 excitation electromechanical motor technology 2001 kgm2 where 18-spoke iron number and round steel spoke iron the same square steel spoke iron thickness 42, 2 fly calculation procedures and results are as follows, page gold material After connection, seal with Nanda 7,3 glue to prevent electrical corrosion. The constant voltage excitation device uses the reactive phase shifting compound excitation type, the reactor air gap is adjustable, and the voltage is provided by the fundamental wave auxiliary winding; the high voltage current transformer is composed of three single phase current transformers, which are respectively connected in series with the motor phase high voltage winding. End; the phase rectifier bridge module for the static rectifier, all the units in the constant voltage excitation device are fixed on the same support plate as a whole, fixed on the top of the motor stator through the shock absorber, and the support plate is grounded by wires. The voltage regulator is composed of a phase rectification bridge voltage adjustment potentiometer, a current regulation amplifier, a square wave generation limiting circuit, a comprehensive amplification current feedback shunt power transistor parallel device unit, and a voltage regulator installed in the electrical control cabinet. Motor assembly structure 4.
4 Conclusions From the domestic and foreign demand in recent years, the analysis and comparison of the results of high-pressure brushless calculations are used. The above calculation results show that the moment of inertia of the 2315 motor round steel is the moment of inertia of the 2,2315 motor square steel. The value is obvious. The moment of inertia of square steel spoke iron is only 75.
4 Conclusion Through the above analysis and theoretical calculations, the cast iron bracket is not conducive to the frequent starting of the motor, has been replaced by the spoke iron structure, and the square steel spoke iron is superior to the round steel spoke iron, its moment of inertia is reduced, which is more conducive to lifting motor Operating conditions.
The first author, Jia Yuqing, was born in 1968. The engineer was awarded the title of advanced workers in the Ministry of Machinery and Electronic Industry of Shanxi Province in 1995. As a diesel power station, there are more and more projects, and the capacity is getting bigger and bigger. From the operation situation of the tens of thousands of generators with a single unit capacity of up to 5000 kW, the high-capacity high-voltage brushless generator excitation system for internal combustion engines is highly reliable with the base-wave auxiliary rib winding brushless phase compound excitation. The main advantage of the high-voltage brushless phase compound-excited generator series is that the generator can continue to operate in the uncontrollable state, ie, the phase re-excitation state; 2 because only the shunt regulation is adopted, the rectifier tube is prevented from being poor in heat dissipation conditions. The problem that the rectifier component is difficult to select makes it damage due to the overload of the low-speed excitation; 4 the external characteristics of the generator are hard, the voltage stability is high when the load is abrupt; 5 the self-excitation pressure of the generator is fast; 6 rotation The rectifier has a simple structure, practical and reliable; 7 the overall structure of the generator is reasonable, the installation is convenient, and the operation is balanced.
Wang Daqing male 1964 student director engineer motor technology 2002
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