Growing penetration of renewable energy sources is leading to a substantial increase in grid impedance across power systems. The grid impedance gives rise to a series of issues, including voltage fluctuations and sags at the Point of Common Coupling (PCC) as well as synchronization difficulties of grid-connected inverters. Most existing approaches rely on optimizing converter control strategies rather than altering the grid's inherent impedance to address this issue. A series grid impedance regulator (SGIR) is proposed in this paper for actively adjusting line impedance. Connected in series between the grid and the load, the regulator emulates a negative inductor in series with the transmission line, thereby canceling the line's inherent inductance. This paper establishes the equivalent circuit model of the SGIR and analytically derives the system's stability conditions and impedance regulation range. Experimental results confirm the efficacy of the proposed SGIR in reducing the equivalent grid impedance to nearly zero through line inductance adjustment, with consistent performance under a wide range of load conditions.
