A proposed design procedure for PI and PID type controllers is presented in the present paper utilizing eigenspectrum assignment as a design tool. As it is well known that the right eigenvector gives the mode shape, i.e. the relative activity of the state variables when a particular mode is excited, while the left eigenvector identifies the weights for the contribution of the activity to the mode. In the analysis and operation of power systems, one needs to assess the influence of some parameter variation that may be a source of oscillations and deteriorate the frequency and tie-line power regulation. This includes what might be considered "natural" modes of oscillations that are due to the inherent system characteristics as well as "forced" modes of oscillations that are driven by a particular system. A comprehensive treatment and evaluation for the sensitivities of eigenvalues and eigenvectors are presented.