Fuzzy Approach to Voltage Collapse based Contingency Ranking

The importance of preventing the voltage collapse is gaining importance due to increase in dependency on the use of electricity. This has compelled the utilities to maintain high system reliability. The evaluation of a power systems ability to withstand dangerous contingencies and to survive to a normal or acceptable operating point is a prerequisite for security analysis. Fast and accurate security assessment, has become a key issue to ensure secure operation of power system. Steady-state security assessment enables the operating personnel to know which system disturbances or contingencies may cause limit violations and force the system to enter into emergency state. Line outages often cause blackouts due to voltage collapse. Voltage Stability Margin of the system on occurrence of specific contingency gives good information about the severity of the contingency of the system. This paper presents fuzzy approach to voltage collapse based contingency ranking. It uses L index as Voltage Collapse Proximity Indicator. This indicator is used as post contingent quantity in addition to bus voltage profiles to evaluate contingency ranking. The proposed approach is tested under simulated condition on IEEE-30 bus system.