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Control Techniques of Grid Connected PWM Rectifiers under Unbalanced Input Voltage Conditions
Bejvl, Martin ; Šimek, Petr ; Škramlík, Jiří ; Valouch, Viktor
Current-controlled voltage source converters are widely used in grid-connected applications,for example at ac drives with indirect frequency converters.The structure and parameters of the PLL are developed and proposed in order to cope with the grid containing both the positive and the negative sequence component, and minimize the wrong frequency transients during phase angle steps and also in the start-up stage. The DSC technique was realised. There is also necessary to compensate the negative sequence component in the grid voltage. The negative sequence component of the grid voltage causes ripple of the dc voltage in the intermediate circuit. Several sophisticated topologies of converter current controller were developed, simulated and tested for this purpose. Results of simulation and experimental tests are provided to evaluate different current control schemes and phase locked loop techniques.
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New Hybrid Power Filter Topology and Control for Application in Industrial Networks
Pecha, I. ; Šimek, Petr ; Škramlík, Jiří ; Valouch, Viktor
The paper presents the new structure and control strategy of the Hybrid Power filter (HPF) with a split passive part. Its impedance is divided into two parts tuned to 50Hz and 250 Hz. The HPF topology is very efficient to mitigate harmonic currents especially for higher frequencies. The HPF functionality is influenced by the grid inductance changes only negligibly. The new HPF characteristics were compared with those for a standard HPF and a classic passive compensation by the simulation done in the Matlab/Simulink environment. The voltage and current values and their harmonic spectra were also measured in the real industrial plant Remarkplast, Ltd. under different conditions.
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Vícehladinový IGBT pulzně řízený usměrňovač
Bejvl, Martin ; Šimek, Petr ; Škramlík, Jiří ; Valouch, Viktor
Příspěvek popisuje vyvinutý napěťový pulzně řízený usměrňovač výkonu 5 kVA založený na vícehladinovém měniči s IGBT prvky. je charakterizován nízkou hodnotou THD síťového proudu a je schopen měnit jeho účiník. Modulární uspořádání síťového filtru umožňuje testovat jak L, tak i LCL typy síťových filtrů různých parametrů. Pulzní usměrňovač je vybaven vektorovým řízením síťového proudu a nadřazenou zpětnovazební smyčkou stejnosměrného napětí.
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