d to be overload. At 00:28 the same line but near to bus 4 burned. 4 minutes later, the per-unit voltage at bus 2 goes down to .94 p.u. .At 00:40, line 2-3 started to be overload near to bus 2. At 01:01 line 1-2 near to bus 1 overloaded, line 2-4 also overloaded , but near to bus 4, and ‘Line 2-4 overheats! Protective measures take effect’ massage appeared, In the same time the system stopped working ,the next massage appeared direct after the last massage was ‘system can not Longer supply load BLACKOUT!!! Simulation must Be restarted’, line 2-4 was disconnected, all lines that connected to bus 2 burned, also line 1-3 from the direction of bus 3 overloaded. At that time the per-unit voltages at the buses were, bus one 1.00 p.u., bus two .0.85p.u., bus three 0.55 p.u., bus four 0.53 p.u, and bus five 0.73 p.u. . The system changed from the above diagram to the next diagram during one hour and one minute. Single-line diagram after simulation of 01:01 hourCommons About The System:We have in the system two generators that give the power to the system, transmissions lines and transformers to transmit the power, and the loads. These three things consist any power system. For normal operation, the total power supplied by the sources must equal to the total power used by the loads plus the losses that happen during the transmission process. But in our system when the load varies the power that has to transmit through the transmission line more than the maximum power that can be transmitted through the line 2-4. When the line 2-4 disconnected the power that has to be supply by the other lines which means more power will be transmitted through these lines. In this case the power will be more than the maximum, which caused overloaded in these lines. After that the system can not work more, then it stopped. Solutions To The System:We faced many problems in our system and the system stopped working...
