Capítulos en libros This paper studies the damping of electromechanical oscillations making use of both the ratio and phase modulation capabilities of static synchronous series sources. The design of the static synchronous series source damping controllers is addressed using eigenvalue sensitivities. The eigenvalue sensitivity with respect to a parameter of a feedback controller estimates the eigenvalue shift when such parameter is changed. The controller design comprises two steps: the design of the phase compensation network and the calculation of the controller gain. A combined method is developed to take advantage of both ratio and phase modulating capabilities of static synchronous series sources. Once the phase controller has been designed and incorporated into the system model, the ratio controller has to be designed taking into account the effect of the phase controller due to the direct relationship between the input of the ratio controller and the phase itself. The suggested approach is illustrated in a simple test system. info:eu-repo/semantics/publishedVersion