The Research Of Automatic Quasi-synchronization Device Based On PCC

The automatic Quasi-synchronization device plays an important role in the power system. As the capacity of the power system and individual generator is extending and the configuration of the system is becoming more and more complex, high demands have been put on the security of power-supply system and the quality of the electric energy, and also on the automatic Quasi-synchronization device. In order to realize parallel connection accurately and safely, such a device is demanded to control a generator to fulfill the Quasi-synchronization condition rapidly. At present, most power plants adopt microprocessor-based, automatic quasi-synchronizing devices whose performances greatly exceed handraulic and analogue devices. With the wide use of this device, great convenience has been brought to the plant operators in synchronizing perorations, and the security of the connecting of the electric machinery groups and that of the power system have been guaranteed , and the connecting time decreased greatly as well which reduces the waste of engergy.This paper discusses Quasi-synchronization condition which must be fulfilled by a generator for safe parallel connection and the influence of the connecting process on generators under different conditions. The results of this analysis provide the theoretical foundation for developing the automatic Quasi-synchronization device. The paper elaborates the important status of microprocessor-based automatic quasi-synchronization device in power system, exhausts the principles of synchronism, and analyzes the deficiency of handraulic and analogue devices.Based on the theories mentioned above, this paper researches automatic Quasi-synchronization device of PCC type. Adopting the system implemented by using Programmable Computer Controller of B&R 2003 and the modular input and output circuit, this device has a high reliability and convenient installation, and can automaticly detect the voltage and frequency of a generator that will be connected by incorporating into the power network and also can control them so that they can rapidly fulfill the Quasi-synchronization condition. When the condition has been fulfilled, it can not only rapidly and accurately put the generator into the system with the minimum influence, but also record the time of a successful connection which serves as a comparison for the next time, and also allows to revise the preparing time on line.