Strategie řízení pulzně řízených měničů za přítomnosti rušivých složek v síti

Abstract

The doctoral thesis is focused on the issue of instantaneous active and non-active power control of electronic power converters connected to the grid, which should work reliably even in case of unsymmetrical grid and/or presence of voltage harmonics. It should assure also good transient responses in case of usual grid disturbances. In the first part of the thesis the motivation to the research and a review of the state-ofthe- art in the field is presented. Also the main aims of the thesis are summarized here. In the following part techniques nowadays used for assuring converter dc voltage with minimum pulsation are described and an overview of their advantages and disadvantages is presented. The principles of the techniques are explained and some simulation results are presented in several subchapters of this part. The methods investigated are critically compared each other from the point of view of their main performance criteria and computation burden. On the basis of the detailed analysis done in the previous part a new power control concept based on a modified instantaneous non-active power theory is presented in the next key part of the thesis. The strategy assures harmonic free converter currents even under unbalanced voltage conditions, which is not the point of the traditional power control strategies. The developed strategy is analyzed according to maximum phase currents as well, which is a crucial condition for dimensioning power converter elements. The dual current controller is used to make the current control fast and reliable enough even in case of unbalanced grid currents. The behaviour of this power control strategy is analyzed and compared to that of the methods reviewed in the previous part via simulation in the Matlab/Simulink environment. In the next part the introduced power control strategy is verified through experimentations. The experimental system consists of the programmable voltage source Chroma 1704 and a digital control unit based on the dSPACE™ control system DS 1005. It is declared that the behaviour of the developed power control method is in line with theoretical expectations and simulation results even under unbalanced grid voltage and, in general, better than that of the commonly used methods based on standard instantaneous non-active power theories, which were reviewed in previous chapters of the thesis. At the end, the main knowledge and results obtained within course of the research are summarized and commented, and some prospective trends in the field are outlined.