Power system stability enhancement using PSS and UPFC Lyapunov-based controllers: a comparative study

Recently it has been shown that it is possible to design a power system stabilizer (PSS) as well as an unified power flow controller (UPFC) controller using a non-linear multi-machine system model in conjunction with Lyapunov´s direct method. In this paper the features of two controllers implementing the proposed control laws have been compared: the PSS constitutes a supplementary loop to the main automatic voltage regulator (AVR) and UPFC controller. Theoretical analysis is supported by the results of eigenvalues analysis and simulations tests, which highlighted the differences between the actions of compared controllers. The tests performed on a multi-machine system model have shown a good performance of both proposed controllers.