Control of unified power flow controller: comparison of methods on the basis of a detailed numerical model

This article is based on results from numerical simulation, including GTOs, of a complete unified power flow controller (UPFC) structure using EMTP (Electromagnetic Transients Program) code. A new type of control is presented. This linear quadratic control allows one to take into account the coupling of the equations in the shunt part of a UPFC. Three types of "power 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.