Abstract: Intelligent impedance injection modules (IIM)s are currently being used for line balancing and overcoming local disturbances on High Voltage (HV) transmission lines of an HV power grid. These distributed IIMs are connected and/or coupled to the HV transmission lines and operate with a pseudo ground at the voltage of the HV transmission line. In order to operate effectively, the IIMs need to communicate with other distributed IIMs across the three phases of the HV grid and also communicate with local intelligent centers LINCs that connect to and synchronize operations across each group of the distributed IIMs in a local region of the HV power grid. Systems and methods are presented for effective and secure sub-cyclic speed communication to and from the distributed IIMs, distributed IIMs to LINCs and substations to enable coordinated actions. Further the distributed IIMs and LINCs receive GPS signals and use the GPS clock for synchronizing operations.