Selection of UPFC suitable locations for system security improvement under normal and network contingencies

Electric power systems are exposed to various contingencies. Network contingencies often contribute to overloading of network branches, unsatisfactory voltages and also leading to problems of stability/voltage collapse. To maintain security of the systems, it is desirable to estimate the effect of contingencies and plan suitable measures to improve system security/stability. The paper presents an approach for selection of UPFC (unified power flow controller) suitable locations considering normal and network contingencies after evaluating the degree of severity of the contingencies. The ranking is evaluated using composite criteria based fuzzy logic for eliminating masking effects. The selection of UPFC suitable locations uses the criteria on the basis of improved system security/stability. The proposed approach for selection of UPFC suitable locations has been tested under simulated conditions on a few sample power systems and the results for a real life 36-node equivalent EHV power network are presented for illustration purposes.