A smooth power flow model of electric power system with generator reactive power limits taken into consideration

This paper deals with a power flow computation model in which generator reactive power limits are taken into account. The power flow computation in such a case includes a trial-and-error process, which mathematically implies undifferentiability. This paper illustrates a new differentiable power flow model that eliminates the trial-and-error process. In this power flow model, a polygonal line representing the Q-V capability characteristics of a generator is approximated by a hyperbola or a sigmoid function. It is demonstrated that correct voltage solutions of the IEEE 30, 57 and 118 bus systems are obtained by using the proposed power flow model.