Prevention of voltage collapse in an isolated network of Saudi Arabia

The isolated network of Rafha (located in North East of KSA) recently experienced blackout incidents initiated by the stalling of induction motors in residential air conditioners during contingency conditions. While stalling, sustained increase in reactive power demand by the motors could not be met by the generators. This problem was exacerbated due to radial configuration of the network, long feeders and the dominance of air conditioner loads during summer season. The main focus of this research work is to propose some corrective measures to prevent voltage instability issues caused by the stalling of air conditioning motor loads. Most effective solutions highlighted by the findings of this study are faster clearing of faults and the application of under voltage load shedding (UVLS). Once voltage recovery process was complete, the restoration of motor loads was also performed and demonstrated through time-domain dynamic simulations in Siemens PTI PSS/E program.