Droop control design for multi-terminal VSC-HVDC grids based on LMI optimization

The paper addresses the control of multi-terminal high voltage direct current (HVDC) networks with voltage source converters (VSCs). A general model is presented in order to describe the behavior of the multi-terminal VSC-HVDC networks in any possible operating condition. Based on this model, we propose a systematic design procedure for computing a decentralized static output feedback (SOF), the so-called droop control, with the aim of controlling the DC voltages. The design procedure is reduced to solving a convex optimization problem with linear matrix inequalities (LMIs). A four-terminal VSC-HVDC grid is use to illustrated the application of the proposed procedure.