Abstract: For the quasisynchronization paralleling of the generator with the system, some conditions, such as voltage, frequency, phase and etc., must be satisfied seriously. Considering that the voltage difference, the phase difference and the frequency difference are existed, the characteristics of the impact current and the influence of the impact current on the generator and the system were analyzed. Based on the result of above analysis and the related parameters of the automatic quasisynchronization device and the closing breaker, aiming at a practical example, the setting calculation of the blocking angle of the synchronization blocking relay was carried out.

Key words: quasi-synchronization, impact current, synchronization blocking relay, setting calculation