Controller for compensation of unbalance and harmonic distortion in an UPS inverter.
Valdez Fernández, Andrés Alejandro
In this thesis the control of an uninterruptible power supply (UPS) is investigated using a combined measurement of capacitor and load currents in the same current sensor arrangement. The purpose of this combined measurement is, reaching a similar performance as that obtained in a capacitor current based controller, and obtain an estimate of the inductor current for security purposes. A controller based on the combined current measurement is proposed to compensate for unbalance and harmonic distortion on the load. Adaptation is included to cope with uncertainties in the parameters of the system. It is shown that after transformations, the proposed controller gets a simple and practical form that includes a bank of resonant filters which is in agreement with the internal model principle. The controller is based on a frequency domain description of the periodic disturbances, which include both symmetric components, namely, the negative and positive sequence, thus, allowing the treatment under unbalance operation as well. As a consequence, the controller compensates only for a selected group of harmonic components. A simple estimator for the inductor current used for protection purposes only is also proposed. The inductor current estimate is obtained in terms of the combined and the capacitor currents. Since the combined current depends directly on the current load, the estimator responds very fast to an over current in the load.
Fecha de publicación2005
Tipo de publicaciónTesis
DirectorEscobar Valderrama, Gerardo
Palabras claveControl adaptable
Tesis y disertaciones académicas
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