The Research On Self-Excitation And Shunt-Excitation Automatic Excitation Device Of The Synchronous Generator

With the development of science and technology and the modernization of production, departments of the national economy develop in the direction of high-speed and automation. And requirement of power supply quality of generator is more and more high. The power supply quality and operating reliability and stability of synchronous generator system are influenced directly by performance and operating reliability of excitation system.The load is always changing when the generator operates normally. The effect on the generator excitation magnetic field is different when the capacity and power factor of load are different,and the effect on the internal impedance voltage drop is different,too. In order to sustain the stable output voltage of generator, we must regulate the excitation at any moment according to the capacity and the quality of load. This regulating course can be realized only through the automatic voltage regulation device. This system will finish the function above.In this task, the automatic excitation system uses trigger circuit which adopts TC787 as its core to take place of the integration KC series trigger circuit which is popular in domestic market. Power dissipation of the trigger circuit which adopts TC787 is small and its function is powerful. High input impedance, powerful ability of anti-interference, wide range of phase-shift and less outward elements are advantages of the circuit. And it can be simply installed and debugged. In addition, it is reliable to put the circuit into practice.The device mainly consists of integrated phase-shift trigger unit, detection unit, amplification and impedance conversion unit, the smallest excitation limitation unit, reactive regulation unit and three-phase controlled bridge rectifier. The device can realize the following functions: automatic stabilizing voltage, contravariant magnet-suppressing, the smallest excitation limitation, residual voltage starting excitation and reactive regulation.In all kinds of power station, excitation system is key device which guarantees that synchronous generator works in normal state and increases stable level of electric network. Though electric system is developing large-scale machine shop in the view of energy saving and reducing waste, small-scale hydraulic power plant and micromidi thermal-electric plant will largely develop because of the national policy of developing small-scale power plant and strengthening environmental protection idea. Therefore, the high performance automatic excitation regulator which is applied in small-scale machine shop will have great market potential.