Approximate decoupling of a condition for voltage collapse

An index for voltage collapse in a power system model with a general dynamic load is roughly approximated and simplified using the standard P-δ, Q-V decoupling. The simplified index measures the closeness to bifurcation of the load reactive power balance equations. It is shown that if the reduction to an approximate index describing the bifurcation of the load reactive power balance equations is still possible, then this would demonstrate analytically the importance of load reactive power balance in voltage collapse