The singularity in power system differential-algebraic model is related to transient voltage stability in the paper. By using a type of dynamic load model instead of static load model

the singularity in DAE is eliminated. Case studies in two-generator single-load three-bus system and New England 39-bus system proved that the system state near singular point has the characteristic of transient voltage collapse. Hence

the singularity of the differential-algebraic model can act as a kind of mechanisms for transient voltage collapse. The influences of time constant in dynamic load model

load power and load constitution on transient voltage stability are also studied. The results indicate that the power system with the load having the constant power and constant current load characteristics and quick response ability is prone to voltage collapse under the heavy load conditions. The above conclusions are helpful for the studies of transient voltage collapse mechanism

relationship between voltage stability and angle stability

theory and simulation methods for power system differential-algebraic model.