Active impedance-injection module enabled for distributed power flow control of high-voltage (HV) transmission lines is disclosed. The module uses transformers with multi-turn primary windings, series-connected to high-voltage power lines, to dynamically control power flow on those power lines. The insertion of the transformer multi-turn primary is by cutting the line and splicing the two ends of the winding to the ends of the cut high-voltage transmission line. The secondary winding of the transformer is connected to a control circuit and a converter/inverter circuit that is able to generate inductive and capacitive impedance based on the status of the transmission line. The module operates by extracting power from the HV transmission line with the module floating at the HV transmission-line potential. High-voltage insulators are typically used to suspend the module from transmission towers, or intermediate support structures. It may also be directly suspended from the HV transmission line.