Abstract: The plant has been analyzed for the loss of the turbine generator due to loss of magnetism and caused the whole plant to jump into a vehicle accident. The turbine generator was demagnetized. Foreword I have a turbine generator set in the plant, of which the 2 121 boundary was established in 1991. After the operation was started in February, the contradiction of power supply in our factory was greatly relieved, but the configuration of the corpse protection and procedures was not coordinated. The whole plant's power supply system brought some questions. At 7:40 on the morning of January 19th, 1991, at the time of handover, the on-duty personnel found that the reactive current of the 12-river unit surged by more than 2,000 people, causing significant swings in power generation. The sound of the machine is abnormal and the power factor lags behind. 2. Afterwards, the Power Supply Bureau provided a small overcurrent 2700 protection action to the inlet switch of the 2nd section of our factory. The generator caused an overcurrent due to the loss of pressure. After analysis, it is caused by a large number of generators losing power after the loss of magnetization, causing a series of jumping faults in the plant. The generator set also occurred in our factory. Has attracted great attention, especially for continuous chemical production is particularly owed 1 observed after the phenomenon of loss of magnetic induction after the loss of asynchronous asynchronous overspeed operation and loss of synchronization before the state of operation there are many differences, can be observed, can also be The electromechanical transient analysis of the demagnetization shows that these 1.1 rotor currents are equal to zero or close to zero. When the generator loses its magnetic force, the rotor current rapidly decays according to the index regulation, and the degree of demagnetization causes the magnitude of residual magnetization. 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 through which the DC voltage may be very small.
1.2 The stator current swing refers to a significant increase in the stator current. In the above shocks, the current should reach nearly twice the rated current of 13750. Due to the need to establish the working magnetizing magnetizing current and leakage flux, the reactive component is large, and the reactive power absorbed by the stator current from the grid increases with the slip rate of 5±3 persons and 3 people are 1 to 1 person, forming the frame system group. State real-time running system maintenance database configuration software, iH spray preparation drive 1 sequence utility software system database online generation file field equipment 5 put into operation and effect 1 foot scene equipment installed on the scene, the total control area than 3 to reduce 3 off, Save costs 20.
21 The intrinsically safe part saves the use of the wire, 31 subsystems save 20, and the degree of automation is greatly improved.
Easy to expand, no point limit, 12,000 field control system has been successfully put into operation, and the distance has been stable for two months. It is expected that the system will increase the annual profit by 250,000 yuan. Wire 61 Cuts sincerely Control efficiency increases because the stator is still connected to the system In the stator windings continue to flow through the relative work current. The rotating magnetic field generated by this current is also the same as the rotating magnetic field. When the rotor rotates in a synchronous manner with a 15 rotor, the rotor is starved. Resistor winding and rotor current, this single-phase current is the rotor's pulsating magnetic field after the generator loses DC excitation. Therefore, when the generator is in a stateless state, the electromagnetic torque of the generator corresponds to the stator synchronous rotating magnetic field and the rotor loop current. The pulsating magnetic field interacts to produce 4 torque components. If the stator rotating magnetic field is, = the rotor speed 7 = 13. If, in the event of an excitation short-circuit, excitation is lost, the rotor rotates with a slip 51 and a ten-step speed. At this point in the excitation winding. The induced slip produces a single-phase pulsating magnetic field that is synthesized by the forward and reverse rotating magnetic fields, that is, the magnetic field six that rotates in the forward rotation of the rotor and the two magnetic field 8 rotates in the opposite direction. The amplitudes of the components synthesized are each ten of a single-phase pulsating magnetic field amplitude. In order to pay for the rotation of the rotor, 5 turns are opposite to each other. Therefore, the speed of the human body is 1+51+5 equal to 1+251. The current of the household is significant. The reason for the same oscillation of the rotor is that 1 is due to the positive magnetic field component of the rotor. A frequency of 1 + 25 AC is induced in the stator windings. The turbulent current is superimposed on the stator fundamental frequency current, thus forming a periodic oscillation, which causes the stator current to oscillate and the amplitude significantly increases. The degree of the current oscillating is related to the connection state of the rotor winding. If the rotor winding is open or closed by a large resistance, it is in the rotor. There is no or only a small amount of current in the circuit, then the positive rotating magnetic field of the rotor established by this current is not present or very weak, and the frequency of 1+2 induced in the corresponding stator is also small, so the current Swing is small When the rotor winding is short-circuited, the slip frequency current induced in the rotor circuit is large, so the stator current swing seriously 21 motor magnetic circuit is not symmetrical, when the machine magnetic circuit is slightly + symmetrical, the same rotor current due to magnetic Where the resistance difference occurs, the magnetic flux density generated by the current is large; where the magnetic resistance is large, the flux density generated by the same current is small. Therefore, the frequency generated in the stator winding is 1+2 current amplitude. Consequent to the fluctuations, the frequency of its oscillations and the speed of the rotation, 13 active power refers to the reduction, and the loss of magnetism into the asynchronous operation of the oscillating torque generator is not Heng, causing speed increases. Outside the range of the failure zone of the governor, the governor automatically closes the small valve, the power transmission of the prime mover is reduced, and the active power output by the generator is reduced correspondingly, until the prime mover turbine torque 1 and the asynchronous torque of the generator seem to balance. When the speeder stops operating, the power output reaches a small, stable value of the initial power of the cadaver. The degree of reduction in active power and the characteristics of the governor The 1.4 reactive power caused by the sibling torque to the rotating magnetic field is negative, the power factor indicates the phase, the generator bus voltage decreases, and the oscillating generator loses magnetization and runs asynchronously. This is equivalent to an asynchronous generator with a slip of 5 The system supplies active power. The other side of the system also absorbs a large amount of reactive power to the system. Therefore, the power is centered on the negative. When the power factor enters the stator current increases, the line voltage drop increases, so the bus voltage decreases, and The current swings and swings. In severe cases, it may cause the system to settle down drastically. The bait will cause a mid-voltage collapse. 1.5 The temperature of the rotor will increase, and the walker's excitation winding will cause a slip current in the transfer core. Magnetic leakage at the end causes additional temperature rise.
May jeopardize the safe operation of the rotor 2 Electromechanical transient analysis after de-magnetization of the generator is an electro-mechanical transient process after de-magnetization of the generator 21 Generator out-of-step generator When the generator has just lost excitation, the rotor is still rotating at synchronous speed The exciter voltage suddenly Small, He Shan in the excitation of the excitation of the road, the rotor loop excitation DC will not be reduced to a minimum, but reduced by exponential law. That is, the stator induced potential at the instant of EqO demagnetization is the initial Eqresd induced potential of the stator due to remanence.
Fixed value 2, set generator synchronous shaft reactance as the heart, then the power sent by the generator decreases with the call (1). In other words, due to the reduction, an unbalanced phenomenon occurs on the rotor, that is, the prime mover appears to cancel out the electromagnetic grasp, and there is also surplus torque, so as to drive the synchronous machine plus, the angle between the dian and the call, and the recovery of the automobile. , The deceleration of the power, balance, 3 The generator is demagnetized and the transient process branches if this state continues. When the excitation is attenuated to a certain value, so that the state had large enough to exceed the static stability limit angle, the generator will eventually lose synchronization under the surplus torque, and the rotor will be accelerated to operate beyond the synchronous speed.
When the middle circle begins to reduce the number of missing holes, the generator gradually transitions to the forward phase operation and absorbs reactive power from the grid. The generator terminal voltage will drop.
When the generator exceeds the synchronous speed, the rotating magnetic field of the rotor and the stator has a relative movement. There is a slip between them. At this time, the rotor has a slip of 5, which exceeds the synchronous speed and enters the asynchronous operation state. According to the analysis. This process takes a few seconds to lose sync. 3, after the motor is lost, a transient process analysis 22 After the asynchronous operation of the generator, the stator winding is still connected to the system, and the relative reactive current flows through the stator winding. The rotating magnetic field generated by this Tunliu is also a synchronous rotating magnetic field. When the rotor cuts the stator synchronous rotating magnetic field with a slip 5, an alternating current of a slip frequency will be induced in the rotor winding teeth and the slot wedge, respectively. This single-phase alternating current will cause the AC excitation to lose the direct current excitation. Current, which in turn establishes a pulsating magnetic field with respect to the rotor at the same frequency. Therefore, the asynchronous operation of the generator is possible, and it also makes it possible to complete the entire step. 3 The de-magnetized critical generator loses its magnetization and then loses its synchronism. When the current fluctuates greatly, the coil generates a strong pulse. May cause material fatigue effects! Mechanical resonance and tune resonance. 0. The end of the motor cable is broken, the motor welding joint cracks, causing a shot; the pulse vibration may also cause damage to the oil film of the shaft bearing, and may also cause vibration of the core, loss increase, and cracks in the large shaft. Etc.; due to a large number of reactive power loss in the loss of magnetization, in the system when the reactive power is insufficient, will cause the system voltage to drop significantly. These drawbacks can jeopardize the safe and stable operation of the generator set and the entire system.
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