Technology Of Current Limit And Break

The growth of electric power consumption has resulted in a corresponding development of power system. And the development of modem power system is towards to super high voltage, large capacity and networking. It tends to the increase of the fault current level in the power system, which is a challenge to the breaking capability of the installed circuit breakers and other equipments. The stability of the power system has been therefore paid more and more attention. Fault Current Limiter (FCL) can protect the power system against the short circuit current.A novel FCL with series compensation is presented in this paper, which is composed of a vacuum switch with a short closing time, a reactive compensation capacitor and a current limiting reactor. The vacuum switch with a short closing time, connected in parallel with the reactive compensation capacitor controls either the series compensation or the short circuit current limitation. In the common state, this FCL reacts as series compensation. When the short circuit fault occurs, the fault will be detected and a closing signal will be sent to drive the vacuum switch rapidly, then the reactive compensation capacitor is bypassed, so that the short circuit current will be restrained effectively.The short circuit current is judged exactly and rapidly, using the Rogowski Coil short current measure element, which uses the judgment criterion of combining current rate and current instantaneous values of fault current together. Thereby, the security and reliability of the entire power system by FCL can be ensured.The short circuit current limiting protection in the different position of transmission line can be carried out using the FCL presented in this design. Three phase short circuit faults in different location of system are simulated using MATLAB. The result shows that the earlier the FCL acts, the more effectively the current can be limited.