The low frequency oscillation problem of the inter-connected power grid will limit the transmission capacity even lead to instability of the power system. Some series connected devices, such as HVDC and TCSC, can be directly used to suppress the energy oscillations in the transmission lines. As the emerging of the parallel AC/DC interconnected power systems, this paper present a coordinated controller of the HVDC and TCSC to damp the inter-area oscillations. Firstly, the equivalent structure and mathematical model is illustrated and represented as generalized Hamilton structure, which is characterized with the oscillation energy of the power system as the Hamiltonian function. Furthermore, the coordinated control strategy, which has a physical meaning of energy balance and damping injection, is designed via Lyapunov stability theory and proven to be effective. Lastly, a parameterized equivalent power system is taken as an example to test the controller and the experimental results demonstrate the effectiveness of the methodology presented in this paper. Copyright (C) 2012 Praise Worthy Prize S.r.l. - All rights reserved.