Protection Study Of Asynchronized Synchronous Generator System

With the rapid development of power industry, it is a tendency for electric energy to be transmitted in long distance, large capacity and high voltage level, which makes the problems of reactive power adjustment, static and transient stability of power systems more and more complex.As the AC-excitation system is adopted in Asynchronized Synchronous Generator (ASG), all of the amplitude, frequency and phase of the magnetizing voltage can be adjusted, which greatly improves the static and transient stability of power system. Under proper excitation control, the reactive power, active power and speed of an ASG can be independently adjusted, respectively. The ability in phase lead operation is superior to that of common synchronous generator, which provides a powerful means for voltage adjustment. These advantages presented above are of great importance for stable operation of power systems. There is a broad prospect for ASG. A few of ASG are operating as motor and generator on the pumped storage station or generator on extra-high voltage transmission lines abroad. It is proved that the ASG is effective method for improve operation characteristics of power system. Now it is studied in the whole world.In this paper, the protection relay of ASG system is studied. Based on analysis the internal electromagnetic relationship of ASG, the base equation, and equivalent circuit, and phase diagram of ASG are got to using the method of induction machine. The active and reactive power characteristics, and the power transmit relationship are analyzed. Under the dq 0 synchronous reference frame, the model of the ASG is derived, which provides the base for further study. Based on the analysis of the different no-load short-circuit faults, the boundary conditions and simulation model of load short-circuit faults for ASG is build up and provide effective method to transient analysis of load short-circuit faults. And the corresponding simulation program which can be available for flexible selection different short-circuit points is set. The short-circuit transient of ASG system is simulated. By analyzed and contrasted the simulation data, the characteristics of short-circuit transient are obtained when ASG connects with the infinite power system. At last, the short-circuit transient is simulated when ASG operates in phase lead. The impact of current protection is analyzed, and the solution is presented.