Modelado del SVC mediante fasores dinámicos para reducción del modelo y diseño de un control lineal

Abstract

In this thesis, the dynamic phasor method is used for modelling the static VAR compensator (SVC) to perform the dynamic and the harmonic analysis of a power system. By using the SVC model, a proportional-integral controller is designed to regulate the voltage in a weak power system. In addition, reduction of the models order dimension is obtained, maintaining the dynamic behaviour of the SVC. The modelling in the so-called \extended frequency domain is developed by means of the dynamic phasor approach, which is dened by the fact that a time-variant quasiperiodic signal can be approximated by a Fourier series with time-variant coecients, since the time interval under consideration slides as a function of time. Therefore, this method allows the study of the dynamic behaviour of the harmonic components of a time variant signal. The SVC models equations, in terms of dynamic phasors that represent the dynamics of the fundamental currents, and voltages and of their harmonics, are linearized using the small-signal analysis, which allows to rewrite the dierential equations in the form of linear state-space. Therefore, the tool for LTI systems, root locus method, is used to design and tune of the PI control. The PI controls performance for the voltage regulation of a weak power system is reviewed. For this task, the MATLAB R /Simulink R software is used to carry out the simulation of a test system in the presence of dynamic changes in the operation, showing that the control is capable to maintain the power systems stability in a critical operation. In this work, a reduced model of the SVC that represents the dynamic behaviour of the reactor currents is proposed. For the model reduction, a suitable voltage regulation in the connection bus of the compensator is assumed, consequently, the variations or disturbances of voltage are small, keeping around the nominal voltage. The project is focused on the design of a PI control derived from the small-signal model of the SVC allowing the use of tools of LTI systems, thus a control that is obtained that is capable to maintain the stability of a power systems with a signicant line impedance.