Composite load sensitivity in voltage stability problem solved by Unified Power Flow Controller

Alleviation of voltage stability problem by using Unified Power Flow Controller (UPFC) represents main concern of this paper. The UPFC is analysed as the device capable of giving voltage support and/or co-ordinating power flow control action. Voltage stability problem is viewed from longer-term time domain response of a composite load model. Sensitivity analysis is applied with respect to parameters of individual elements of the composite load model. Computational procedure reveals critical load parameters as well as critical time instant during time domain trajectory. The UPFC is accordingly initiated to simultaneously support bus voltage magnitudes and adjust power flow through the line in order to decrease total active power loss.