This article is based on results from numerical simulation, including GTOs, of a complete Unified Power Plow Controller (UPFC) structure using EMTP (Electromagnetic Transients Program) code. A new type of control is presented. This Lineal Quadratic control allows to take into account the coupling of the equations in the shunt part of a UPFC. Three types of ''converter control'' are simulated. They are compared in relation to capacitance rating, transformation ratios, switching losses and harmonics. Choice of the most suitable command-control method will result in a reduction of losses and of the harmonics injected into the system, and will optimise the rating of the component elements of the UPFC.
