The Necessity for Considering Distribution Systems in Voltage Stability Studies

As stated in literature, when a load is of the constant power type, the voltage stability limit point coincides with the point of maximum power transfer. But when a part of load is voltage dependent, such as polynomial load, the voltage stability limit extends beyond the maximum power point. It means that parts of the lower portion of the bus PV curve are stable. This paper shows that because of the distance between the distribution transformers equipped with LTC mechanisms and the transmission buses, the voltage instability occurs before reaching the maximum power transfer point at the transmission buses. In this condition, the voltage collapse point can't be determined using an aggregate load model seen from a transmission bus, and a detailed model of distribution system is needed

کلیدواژه ها:

Voltage stability ، Distribution systems ، Saddle-Node Bifurcation ، Load characteristics