Voltage Stability Assessment in Radial Distribution Network using Voltage Stability Indices

Increased power demand and constrained power resources have made assessment of voltage stability in power system networks necessary in these days to predict voltage instability in order to ensure safe and secure operation of power systems. Also, due to numerous factors the existing power system networks are forced to operate at its peak limit. Therefore, it is essential to assess the maximum voltage stability prior to occurrence of voltage collapse. This will be used as preliminary information by the operator to avoid complete interruption of power system. In this paper, numerous Voltage Stability Indices (VSI) are presented to assess the voltage stability of a Radial Distribution Network (RDN). VSIs are computed from the load flow solution data. The determined VSI also points out the most vulnerable lines or buses those are likely to get voltage collapse. Different VSIs are evaluated for IEEE 15, 33, 69 and 85 bus RDN with nominal and peak power demand. The obtained results have highlighted the importance of voltage stability prediction in RDN for initiating necessary action to avoid voltage collapse from being arising.