In the last years the energy production share of power electronics-based generators has kept increasing with respect to the synchronous generation. These power electronicsresources do not offer rotational inertia, resulting in a decrease of the total system inertia and thus in larger frequency deviations during disturbances. Among several corrective solutions studied in literature, controlling the load consumption is a promising one. Fast in power response and widely distributed in the grid, load control is able to work as power reserve (both upwards and downwards) during frequency variations. In this regard, a Smart Transformer (ST) based solution is proposed. The ST is able to shape load consumption accurately by means of an On-Line Load sensitivity Identification-based (OLLI) control, and can support the primary frequency regulation in the power system. This paper presents an ST-based Real Time Frequency Regulation (RTFR) controller that varies load consumption by means of a voltagebased load control, in response to the frequency deviation in the power grid. The proposed method is described analytically and tested by means of a Power-Hardware-In-Loop experiments, in order to show the effectiveness of the RTFR controller in real time conditions and applications.