1 Abstract The plant's jumping accident caused by the loss of magnetism of the steam turbine generator was analyzed. The turbine generator was demagnetized. The foreword of our factory has a set of steam turbine generator sets, of which 2 121 were in 1991. After being put into operation in February, the contradiction of power supply shortage in our factory was greatly alleviated, but the configuration of the corpse protection and procedures was not coordinated. Brought some questions to the whole power supply system. At 7:40 on the morning of the 20th of 1991, when the shift was in the shift, the duty officer found that the 12-Hebei unit's reactive current increased by more than 2,000 people. The machine sound is abnormal and the power factor is greatly delayed. 2, after, the power supply bureau for the 2 section of the plant into the line switch small overcurrent 2700 into the protection action, the generator caused by overvoltage low-cycle blocking over-current protection action trip, the whole plant stopped production. After analysis, it is caused by the loss of power of the generator, which causes a large number of generators to absorb the reactive power of the generator and cause a series of jumps. This kind of fault has occurred in the generator set of our factory. Therefore, the generator has lost a lot of damage and should be damaged. It is highly valued, especially for continuous chemical production. 1 Observed after loss of magnetism. There are many differences between asynchronous overspeed operation after generator demagnetization and synchronous operation before demagnetization, which can be observed or passed. Electromechanical transient analysis of demagnetization, it can be seen that the other 1.1 rotor current fingers in these zones are equal to zero or close to zero. When the generator loses strong magnetic force, the rotor current rapidly decays according to the index, which reduces the degree of demagnetization caused by the loss of magnetism. When the excitation circuit is open, the rotor current is zero; when the excitation circuit is short-circuited or closed by a small resistance, the rotor circuit has a current, and the DC voltage may be small. 1.2 Stator current swing means that the stator current increases significantly, and the current should reach nearly twice the rated current of 13750 when oscillating in the above accident. Due to the need to establish the working excitation magnetization current and leakage flux, the reactive component is large, and the reactive power absorbed by the stator current from the grid increases by 3±1 elbow with the slip rate of 5±, which constitutes the frame system group. Before the real-time running system maintains the database configuration software, the iH spray drive driver 1 sequence utility software system database online generation file field device 5 put into operation and the effect 1 foot view equipment is installed on the scene, the total control area is reduced by 3 off 3 Save money 20. 21 intrinsically safe parts save Wire, 31 subsystem saves 20, and the degree of automation is greatly improved. The expansion is easy, there is no limit on the number of points, and the 12000 field control system is successfully put into operation. It is stable and normal for a few months. The system can increase the efficiency by 250,000 yuan per year. The efficiency of the control is improved because the stator is still connected to the system. The continual flow of the symmetrical current is continued in the stator winding. The rotating magnetic field generated by this current is also the same, rotating magnetic field. When the rotor rotates the magnetic field synchronously by sliding the scorpion, the rotor is hungry. The resistance winding and the rotor flow, this single-phase current is the magnetic field of the 1 rotor pulsing after the generator loses the DC excitation. Therefore, when the generator is in a small state, the electromagnetic torque is the synchronous rotating magnetic field of the stator and the current of each loop of the rotor. The pulsating magnetic field interacts to produce 4 torque components. If the stator rotating magnetic field is YES, then the rotor rotational speed is 7 = 13. If the excitation is lost in the case of the excitation short circuit, the rotor rotates with the slip 51 and the high ten-step rotational speed. At this point in the field winding. The induced slip turbulence produces a single-phase pulsating magnetic field, which is synthesized by a magnetic field that rotates in the forward and reverse directions, that is, two magnetic fields 6 that are opposite to the forward rotation of the rotor and eight magnetic fields that rotate in the opposite direction. The components are composed of their amplitudes of ten for the amplitude of the single-phase pulsating magnetic field. The rotation of the rotor is 5 昀 opposite to each other. Therefore, the rotation speed of the person is 1+51+5 is equal to 1+251. The current of the household is significant, and the reason for the oscillation oscillation is 1 due to the rotor's positive magnetic field component. The alternating current induced by the person in the stator winding is 1+25. The turbulence is superimposed on the fundamental frequency of the stator, thereby forming a periodic oscillation, causing the stator current to oscillate and the amplitude is significantly increased. The degree of current swing is related to the connection state of the rotor winding. If the rotor winding is open or closed by a large resistance, the rotor is There is no or only a small amount of current in the loop. Then the current is rotated by the rotor. The forward rotating magnetic field is not present or weak. The current induced in the stator is 1+2, so the current is constant. When the rotor winding is short-circuited, the slip frequency current induced in the rotor circuit is large, so the stator current swing is severe. 21 The motor magnetic circuit is not symmetric. When the crankshaft magnetic circuit is slightly + symmetrical, the same rotor current is due to magnetic Where the resistance is different, the magnetic flux density generated by the current is large; where the magnetic reluctance is large, the magnetic flux density generated by the same current is small. Therefore, the frequency generated in the stator winding is 1+2. With the fluctuation, the fluctuation frequency and the rotation speed are caused, 13 active power refers to decrease, and the oscillating generator loses magnetism and enters the asynchronous operation. Outside the range of the governor failure zone, the speed control automatically closes the small valve, the prime mover transmission power is reduced, and the active power output of the generator is correspondingly reduced until the prime mover turbine torque 1 and the generator asynchronous torque are balanced. The speed stop stops, the power output of the power reaches a certain stable value of the initial power of the small body, and the active power decreases to the extent that the characteristics of the governor and the structure of the generator and the swing of the power of the four powers are positive. The reactive power of the double-slip frequency generated by the rotating magnetic field is 1.4, and the reactive power is negative. The power factor refers to the phase, the generator bus voltage value drops, and the swing generator loses magnetism to asynchronous operation. It is equivalent to an asynchronous generator with a slip of 5. The system transmits active power, and the other side also absorbs a large amount of reactive power to the system. Therefore, the power point is negative, and the power factor is increased. As the stator current increases, the line voltage drop increases, so the bus voltage decreases, and The current swings and swings. In severe cases, the system's rolling pressure may drop drastically, and the voltage of the bait will collapse. 1.5 The temperature of each part of the rotor rises. The excitation winding of the hair machine is different from the walking, and the slip current is generated at the rotating iron core. The end is magnetically leaked, etc., causing an additional temperature rise. It may endanger the safe operation of the rotor. 2 Electromechanical transient analysis after the generator is demagnetized. After the generator is demagnetized, it is an electromechanical transient process. 21 When the generator is out of step, the generator is just losing excitation. The rotor is still rotating at the synchronous speed. Small, He Shan's high sensibility in the excitation circuit, the rotor circuit excitation DC will not be reduced to a minimum, but will be reduced exponentially. That is, the stator induced potential initial Eqresd of the instantaneous EqO loss of magnetism is due to the stator induced potential generated by the residual magnetization. The fixed value is 2, and the synchronous reactance of the generator direct shaft is set as the heart, and the power sent by the generator is reduced according to the call (1). That is to say, due to the reduction, there is a phenomenon of unbalance on the rotor, that is, the prime mover seems to be used to offset the electromagnetic grab, and there is residual torque, thereby driving the synchronous machine plus, the angle between the and the called, the recovery of the steamer. , the power of the off power, balance, 3 is the transient process after the generator is demagnetized, if this state continues to go. When the excitation decays to a certain value, causing the state to be larger than the static stability limit angle, the generator will lose synchronization at the residual torque and the rotor will accelerate beyond the synchronous speed to operate. At the middle boundary, when the pound starts to lose less holes, the generator gradually transitions to the phase-in operation, and the power grid absorbs the reactive power, and the generator terminal voltage will definitely drop. When the generator exceeds the synchronous speed, the rotor and the stator have a relative motion of the rotating magnetic field, and there is a slip between them. At this time, the rotor slips by 5, beyond the synchronous speed, and enters the asynchronous state. According to analysis. Generally, this process takes a few seconds to lose synchronization. After the motor fails, the transient process analysis 22 asynchronous operation of the generator is demagnetized. Since the stator winding is still connected to the system, a relative reactive current flows through the stator winding. The rotating magnetic field generated by this turbulence is also a synchronous rotating magnetic field. When the rotor cuts the synchronous rotating magnetic field of the stator by slip 5, in the rotor winding teeth and the wedge, the alternating current of the slip frequency will be induced respectively, and the single-phase AC 屯 will lose the DC excitation to the AC excitation. The current, which in turn establishes a pulsating magnetic field relative to the rotor at the same frequency. Therefore, the asynchronous operation of the generator is possible, and the re-step is made possible. The 3 loss-of-magnetic generator is out of step after the demagnetization, and the coil generates a strong pulse when the current is greatly oscillated. May have the fatigue effect of the material! Mechanical resonance and helium resonance 0. The end of the motor is broken, the motor welded joint is cracked, causing the shot; the pulse vibration may also cause damage to the oil film, which may cause the core to vibrate, the loss increases, and the large shaft crack Etc.; due to a large amount of absorption of reactive power during demagnetization, when the system is insufficiently reactive, the system voltage will drop significantly. These drawbacks can jeopardize the safe and stable operation of the generator set and the entire system.
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