# Minimum Power Losses Based Optimal Power Flow for Iraqi National Super Grid (INSG) and its Effect on Transient Stability

Sammanfattning: In the present work Optimal Power Flow (OPF) with minimum net work losses for Iraqi National Super Grid (400kv) INSG which consist of 19 load buses and 6 generating buses was studied. The losses were calculated and compared with that in case of ordinary load flow which is equal to 37592 MW according to data of generation and load on 2/1/2003.Mathematical model using Lagrange method programmed in Matlab5.3 language was used to reduce network active power losses by injecting active and reactive power in the network load buses according to the sensitivity of each bus to reduce network losses with respect to injection power in the buses. It was found that minimum losses in the network is equal to 21.824MW in case of injecting 180,200,210and 300MW in the load buses 7, 8, 9 and11 respectively. Also the minimum losses in the network are equal to 32.64MW in case of injecting 150,120,120,120,100 and 310MVAR in the load buses 5, 7, 8,9,10 and11 respectively. Optimal generation for the present six generating units which gives minimum network losses was calculated. The effect of removing transmission lines and generating units on OPF was studied for six different operating cases.Also the effect of three phase faults in the middle of transmission lines on OPF and transient stability was studied. In this work step by step integration method has been used. It was found that the worst case takes place in the case of three phase fault in the middle of transmission line (3-4) HAD-QAM which causes system instability.

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