The paper presents voltage stability analysis of radial distribution networks. A new voltage stability index is proposed for identifying the node, which is most sensitive to voltage collapse. It is shown that the node, at which the value of voltage stability index is minimum, is more sensitive to voltage collapse. For the purpose of voltage stability analysis, constant power, constant current, constant impedance and composite load modelling are considered. It is seen that with the insertion of shunt capacitor, load capability limit of the feeder has increased for all types of loads. By using this voltage stability index, one can measure the level of voltage stability of radial distribution networks and thereby appropriate action may be taken if the index indicates a poor level of stability. The proposed method is compared with the other two existing methods. The effectiveness of the proposed method is demonstrated through two examples.
Keywords: radial distribution networks, voltage stability index, voltage collapse, voltage stability analysis