Various control devices, such as shunt banks, on-load tap changers, and static var compensators, can be connected to a microgrid. Depending on the operating schemes, some of these controls may hierarchically actuate in the system to maintain reactive power reserve. This paper proposes a formulation based on sigmoid functions to perform the hierarchical actuation of control devices in the power flow problem. The methodology was generalized to accommodate N hierarchy levels, where N is the number of control devices. The sigmoid function deals with the operational device, and when it reaches its limits, it activates the performance of the subsequent one. To achieve this, the methodology incorporates equations obtained from combining the steady-state characteristics of the control devices and the sigmoid functions into the power flow formulation. These equations are solved simultaneously with the power flow equations in polar coordinates using the full Newton's method. The methodology is evaluated by applying it to two test systems: 11-bus test system and the well-known Nordic system. The results demonstrate the effectiveness of the proposed approach.