When connecting two generators together (in parallel), there are conditions that must be met and fulfilled before commencing the electrical connection process, which are known as synchronization conditions. In this paper, the loss of equality voltages which is one of the synchronization conditions will be represented when performing the connection process using Matlab and surveying the impact of this on the performance of the system and the extent of damage that may result from it. The presented analysis shows the influence of faulty synchronization on the following physical quantities: internal voltage, stator current, stator voltage, angular mechanical speed, terminal voltages which are the most vulnerable. In addition, knowing the type of fault (short circuit fault) caused by the faulty synchronization condition. In this paper, over and under voltage schemes have been implemented by using MATLAB/SIMULINK.

The effect of the various winding connections of three phase two windings transformer on the fault current at the line to ground (SLG-fault) and the double line to ground (DLG-fault) is studied. The ground faults are unbalanced ; so, the analysis of these types of short circuit faults is divided into three balanced circuits which are known as symmetrical networks. The zero sequence impedance appears in some types of transformer connections and its effect is reflected in the fault current value. This paper examines with help of MATLAB software by simulating a generating station and different transformer connections, the impact of three-phase two windings transformer connections which occurs on a transformer secondary side to determine which the connections type of the transformer gives the maximum and minimum zero sequence component of ground fault current.