【正文】 8 14 CCT for fixed speed(ms) 186 187 263 220 CCT for variable speed(ms) 286 216 300 227 According to results, it is very clearly that the DFIG generator increase the critical clearing time, consequently this type of generator presents best performance than a squirrel cage induction generator concerning the angular stability of grid connected to wind power, it is evident that the Wind power generation with DFIG provides better performance for angular stability after fault clearance owing to its ability to control reactive power. Effect of wind peration In this section, the effect of wind power on the oscillations is investigated by gradually increasing the rate of wind source peration while observing the transit behavior of system [11]. Table 4. CCT for different rates of wind power peration Rate of wind sources peration (%) ≥ 22 Installed capacity of Wind sources (MW) ≥172 CCT (ms) 271 229 151 97 00 From the results, it is concluded that the effect of wind power on power system oscillations depends on the rate of wind power peration, it has been proven that a high level of wind power peration such in our case study is must be lower than 22 % of total grid power, otherwise the test system lost its stability. Conclusion This paper has mainly focused on the assessment of the angular stability by determinate a critical clearing time (CCT), This was done by observing the behavior of speed generators of the test system included a three phase fault when changing several parameters. According to previously simulations, the following conclusions are obtained: ???There is no general statement possible, if wind generation improves transient stability margins or if the impact is rather negative. The answer depends on location of wind resources and the problem has to be analyzed individually for each case. ? The effect of type of generator technology in transit stability is very significant and the DFIG generator presents more performance than a squirrel cage induction generator. ? It has been proven that a high level of wind power peration destabilize the power system when a very large part of the synchronous generation capacity is replaced by wind power. Finally, it very important to note that a calculation of a critical clearing time (CCT) in all previous simulations was done by several times which represent a wasting of effort and time so a numerical method of putation of (CCT) is very required for such transit stability studies. References 1. Sun T., Chen Z., Blaabjerg F., Voltage recovery of gridconnected wind turbines after a shortcircuit fault, Annual Conference of the IEEE Industrial Electronics Society, Virginia, USA, 2020. 2. Saffet Ayasun, Yiqiao Liang, Chika O. Nwankpa, A sensitivity approach for putation of the probability density function of critical clearing time and probability of stability in power system transient stability analysis, Applied Mathematics and Computation, 2020, p. 563. 3. Salman S. K., Teo A. L. I., Investigation into the Estimation of the Critical Clearing Time of a Grid Connected Wind Power Based Embedded Generator, Proceedings of the IEEE/PES transmission and distribution Conference and exhibition 2020, Asia Pacific Pucific, Vol. 11, 2020, p. 975980. 4. Jauch C., S248。rensen P., Iov F., Blaabjerg F., Initialisation of GridConnected Wind Turbine Models in PowerSystem Simulations, Wind Engineering, 2020, 27(1), p. 2138. 9. Nandigam K., Chowdhury B. H., Power flow and stability models for induction generators used in wind turbines, IEEE Power Engineering Society General Meeting, 2020, 2, p. 20202020. 10. Hansen A. D., Michalke G., Fault ridethrough capability of DFIG wind turbines, Renewable Energy, 2020, 32, p. 15941610. 11. Ha L. T., Saha T. K., Investigation of Power Loss and Voltage Stability Limits for Large Wind Farm Connections to a Subtransmission Network, Power Engineering Society General Meeting, 2020, 2, p. 22512256.