With the concept of global energy interconnection being proposed, half-wavelength alternating current transmission (HWACT) technology becomes of more interest. HWACT lines can be adopted to establish a pointto-grid system, in which the penetrating power (PP) is produced between receiving terminals, having a significant effect on the power flow distribution. In order to investigate this phenomenon, the PP characteristics of the HWACT system are researched in this paper. First, the mathematical relationship between the transmission power and terminal bus voltages of a single HWACT line is derived using the equations of a distributed parameter model. The research indicates that the relationship between power and terminal voltages shows ‘‘reverse characteristics’’ opposite to those of regular short transmission lines. Then, the concept and definition of PP in a point-to-grid system with two receiving terminals are proposed, and the corresponding relationship between PP and the terminal bus voltages is derived. Simulations are carried out to validate the theory under different conditions, so that the accuracy and adaptiveness of the theoretical analysis can be proved. In addition, the results demonstrate that selecting the location for a HWACT system has demanding requirements in order to control the value of PP.