Power system damping from real and reactive power modulations of voltage-source-converter station

As gas turbines, wind farms, run-of-river hydro, photovoltaic and other renewable energy sources are becoming a growing component in the power system, the feasibility of applying the controllability of their expensive frequency-changers [based on voltage-source converters or (VSCs)] is examined to provide system damping. It is shown that irrespective of the location of the VSC-frequency changers along the transmission line, significant damping is available by the combined control of real and reactive power modulations. The finding is reached by eigenvalue analysis of the linearised equations and confirmed by digital simulation (PSCAD/EMTDC). Digital simulation is also applied to evaluate the size of injected complex power required for the best damping for a given converter rating.