Series compensator inserting real and reactive impedance into electric power system for damping power oscillations

A method for suppressing power transmission system (1) in series compensator with power oscillator (11), a switch power transformer (13), a (5) injecting a voltage to the transmission line, wherein a transmission-line current phase angle of with relate to control, wherein providing reactive compensation to inject and efficient working impedance to the transmission line. The switch power transformer (13) is a dc-ac converter, comprising a comprises and DC end (29) power switching device (27), a inject the efficient working impedance to the transmission line. The one power switching device (27 ') is a resistor device (37), a switch power transformer (13) when the transmission line (5) experiences the power and a surge the active power. In addition, the power switching device (27) is a memory unit (31), a of the battery or a superconducting magnet, wherein the shell, a switch power transformer (13) capable of providing efficient plus and minus active impedance.