Processing of Synchronous Voltage in Synchronous Generator Automatic Excitation Regulator
Processing of Synchronous Voltage in Synchronous Generator Automatic Excitation Regulator Liu Wei (Nanjing Institute of Technology, Nanjing 210013, Jiangsu, China). Therefore, the processing of the synchronous voltage in the semiconductor excitation system and the microcomputer excitation system is analyzed and compared. The time should be after the natural commutation point of the phase. If the automatic excitation regulator (AER) of the natural synchronous generator in this phase is an important automatic device in the power system, the task of the phase shifting trigger unit is to generate a change. The phase pulse is used to trigger the thyristor in the rectifier bridge, so that the control angle changes with the change of the generator terminal voltage, thereby achieving the purpose of automatically adjusting the excitation. The phase shifting trigger unit is composed of synchronization, phase shifting, pulse forming, pulse amplification and the like. If the synchronous voltage is not handled well, it will affect the accuracy of the phase shift trigger pulse, thus affecting the excitation of the generator. The generation of synchronous voltage in a semiconductor excitation system is cumbersome, and with the application of a microcomputer, it provides great convenience for the processing of the synchronous voltage. 1 The role of the synchronous voltage According to the requirements of the conduction control of the thyristor in the thyristor rectifier circuit, the voltage applied to the thyristor component and the trigger pulse applied to the control electrode must be matched in phase, otherwise The thyristor will not work properly, and this cooperation is called synchronization. Therefore, in the thyristor excitation system, a synchronous voltage must be introduced to ensure synchronization of the thyristor trigger pulse with the main circuit. 2 Synchronous voltage generation Synchronous voltage acquisition and controllable rectification circuit wiring type In the three-phase semi-controlled silicon rectification circuit, since the rectifying elements of the common anode group are uncontrollable, commutating at the natural commutation point, the common cathode group of the thyristor The anode voltage that should be withstood is triggered in a certain interval, and the three-phase trigger pulse should be separated by +A, +B, +C phase sequence in 120 three-phase fully controlled silicon rectifier circuit, and the common cathode group of thyristor Only in the interval where the anode potential is the highest, it is possible to conduct. The starting pulse for the cathode group should be issued during this period. The three-phase trigger pulse should be sent out at intervals of +, +8, +匚 in sequence. . The thyristor of the common anode group is only possible to conduct in the interval where the cathode potential is the lowest, and the trigger pulse of the common anode group should be emitted in this interval. The three-phase trigger pulse shall be issued in the order of 120* in the order of one C, one A, and one B. Such a six-phase trigger pulse should be issued at 60. Therefore, the phase shifting trigger unit must accept a voltage signal having a phase relationship with the main circuit voltage to ensure that the trigger pulse is issued as required. The synchronous voltage can be obtained by a synchronous transformer, and the synchronous voltage is converted into a synchronous voltage having the amplitude, phase and phase number required by the trigger circuit by using an appropriate connection method, as a synchronization signal of the phase shifting trigger unit. 3 Synchronous voltage processing 31 Processing of synchronous voltage in semiconductor excitation regulator In the semiconductor excitation regulator, the primary winding of the synchronous voltage is connected to the power supply of the main circuit, and the secondary winding is connected to the three-phase Y-shape in the three-phase half-controlled bridge. In the three-phase full control bridge, a six-phase double Y-connection method is adopted. According to the working characteristics of the fully controlled silicon rectifier bridge: when the control angle is 0°90*, the fully controlled silicon rectifier bridge works in the inverter state. It is not enough to simply introduce the above synchronous voltage (U*), and the synchronous voltage must be processed. In order to meet the requirements of the trigger pulse. In the three-phase full-silicon rectifier bridge circuit, the trigger pulse for applying the trigger pulse is turned on, and since the pulse generator is unlikely to be pulsed again after the natural commutation point, the phase thyristor is actually lost. The pulse is not possible to conduct. Since the time of the trigger pulse is not very accurate, the earliest pulse should be sent a certain distance from the natural commutation point. Therefore, the minimum control angle "min voltage U7a, mn. must be introduced. Due to the use of a fully controlled silicon rectifier bridge, when the generator needs to be quickly demagnetized, the rectifier bridge should be operated in an inverter mode. At this time, the trigger pulse should be changed naturally. After the phase point is 90*, the inverter will be more effective after the phase is crossed. However, for reasons similar to the foregoing, if the pulse phase exceeds 180*, the thyristor is not conducting and cannot be inverted, so the pulse phase should be issued before 180* at the latest. Therefore, it is necessary to introduce the voltage U7a,max of the maximum control angle aman. In addition, according to the trigger pulse having a certain amplitude requirement, a charging voltage U7 is also introduced. It can be seen that in the semiconductor three-phase full-silicon rectifier bridge, four synchronous voltages are introduced for one thyristor, namely: U7tl, U7 charge, U7a, mn, U7aimK, and 24 phases are introduced for 6 thyristors. Different sync voltages. In addition, in the semiconductor excitation, the three-phase controllable rectifier bridge is a large load for the auxiliary excitation. The conduction and shutdown of the thyristor will cause the distortion of the anode power supply voltage waveform to be severe, so the synchronization is caused. The problem of voltage waveform distortion must also be taken seriously, otherwise it will affect the normal operation of the phase shift trigger circuit. The distorted synchronizing voltage is usually first filtered or shaped to eliminate the effects of distortion. It can be seen that in the semiconductor excitation, the generation of the synchronous voltage is troublesome, and debugging is also difficult. 3.2 Processing of Synchronous Voltage in Microcomputer Excitation Regulator 3.2.1 Processing of Synchronous Voltage Block Diagram Principle The three-phase AC voltage emitted by the auxiliary exciter reduces the voltage, isolation and phase shift through the synchronous transformer. The synchronous transformer adopts A/2Y connection method. It is to add the impedance of the main power supply and phase shift the input voltage to obtain a voltage of 90* ahead. Then, the output voltage of the synchronous transformer is subjected to second-order active filtering to obtain a voltage with a phase lag of 90*, which is in phase with the voltage of the auxiliary excitation machine. Finally, the voltage is obtained by the voltage comparator to obtain a gate signal corresponding to the natural commutation point, and the gate signal is connected to the programmable timer counter (8253) to form a power voltage state word. The various parts of the block diagram are analyzed below. As shown in the internal wiring of the synchronous transformer, the primary side is connected in an eight-shape to eliminate the influence of the zero sequence. There are 6 windings on the secondary side, and the reverse polarity of C2 and b2 is reversed to obtain the reverse polarity of Mja, a2 and C2. Obtaining åŸ, b2 and a2 reverse polarity phase string to obtain ujc. Draw the phasor relationship diagram of U7, Ub, Ujc and primary voltage Uab, Ubc>team a - as shown, it can be seen that the former is 90* phase angle before and after. The second-order active filtering function is to filter out the waveform distortion caused by the full-controlled rectifier bridge load, and obtain the voltage with phase lag of 90*. This voltage is not affected by the main power waveform distortion, and the phase and the secondary excitation machine are issued. The three-phase AC voltage phases are in phase. For the three-phase synchronous voltage shaping circuit, after the filtered voltages Ma, Mb, and Uc of the synchronous transformer secondary voltage are passed through the voltage comparator, three square waves (eg,) having a width of 180* and a distance of 120* are formed, and the rising edges thereof are respectively Corresponding to the natural commutation point 1, 3, 5. For the three-phase full control bridge, three inverters must be added to form six square waves with a width of 180* and a distance of 60*, and the rising edges correspond to the natural commutation point 1, respectively. 2, 3, 4, 5, (6 then send 6 synchronous voltage gating signals into 8253. Synchronous voltage gating signals. Beijing: China Electric Power Press, 1998 Fan Jun. Synchronous generator semiconductor excitation principle and application Beijing: Water and Electric Power Press, 1991. Ding Ermou. Synchronous Generator Excitation Regulator. Beijing: China Electric Power Press. Welcome to subscribe, welcome to submit, welcome to advertise 4 Seaters Golf Carts,4 Seaters Gas Golf Carts,4 Seaters Electric Golf Carts,4 Person Golf Cart Yongkang Jinghang Sightseeing Vehicle Co., Ltd. , https://www.jhgolfcarts.com