Large disturbance voltage stability studies in a single machine load bus system

The objective of this paper is to highlight the basic issues involved in maintaining the voltage stability of a single machine load bus system following a large disturbance. The corrective measures considered are the use of reactive power (both fixed reactive power and fixed capacitor) compensation schemes and load shedding. The disturbances considered are network and load changes. The main feature of the analysis is obtaining, wherever possible, a closed-form analytical expression for both the amount of compensation required or the load to be shed and the critical control time of the corrective measure adopted to maintain post-disturbance voltage stability with a specified safety margin. A new contribution is made in modelling the load for disturbances involving a sudden load change.