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A model predictive control (MPC) is proposed for a buck-type active power filter (APF) integrated single-phase quasi-Z-source inverter (qZSI) to directly eliminate the dc-side low-frequency ripple power. The buck-type APF operates independently from the main circuit power devices, comparing to the coupled-type APF. The proposed MPC compensates the low-frequency ripple power directly by the APF capacitor...
Present work aims to remove the source current harmonics of order 6n±1 where, n is an integer present in power utility system under realistic scenario. This realistic scenario represents a harmonically unbalanced condition which is caused by multiple non-linear loads attached to different phases of 3-phase power supply. It creates different amplitude spectrum of individual source current harmonic...
The present work aims to remove dominant current harmonics (5th,7th,11th and 13th) of a 240V(rms) utility at the point of common coupling for the harmonically unbalanced condition of source current, using parallel combination of two shunt hybrid active filters. The harmonically unbalanced condition of source current has been created by connecting different types of non-linear loads in different phases...
This paper proposes a synergistic operation of distributed compensators. By a synergistic operation, a part of a distribution system can behave as a single element. Two distributed compensators are responsible for achieving the operation. The grid may demand three requirements from the element: cancellation of the input current, operation under unit power factor and injection of active power into...
Parallel-connected inverters are used for high power application. Due to the parallel-connection, there exists a circulating current which does not contribute to the ac side current. The analysis presented in the paper shows that the circulating current is affected by the dead-time. The effect of the dead time on the circulating current for the space vector pulse width modulation (PWM) and a discontinuous...
This paper presents comparisons of active power filter (APF) and hybrid power filter (HPF) systems. Despite numerous studies on the two filters, there is not clear analysis between their differences and the HPF features. This paper analyzes the HPF inverter along with passive power filters (PPFs) and their effects on the power factor at the grid. Additionally, a theoretical analysis and systematic...
A method for calculating the coupling inductance of active power filters (APFs) is proposed in this paper. The current ripple is defined and its relationship with the coupling inductance value is deduced based on error analyses. Hence, the lower boundary of the inductor value could be determined from the current ripple limit. A method to estimate the upper boundary of the inductor value is also proposed...
Predictive current controller is often adopted to compensate time delays caused by digital control. But traditional predictive current control algorithm for four-quadrant converters is an open-loop current observer essentially. Current value predicted is affected by many factors such as grid voltage extrapolation error, inductance error and dead-zone time. All of them will aggravate the grid current...
Harmonic Cancellation Technique (HCT) is a modulation technique which has been developed to reduce the output voltage THD of three phase voltage source inverters (VSI) when they are used to feed simultaneously both linear and non-liner loads. The HCT is based on the proper pre-distortion of the inverter output voltage in order to cancel out the low frequency harmonic content due to the non linear...
A novel scheme for three-phase grid-connected photovoltaic (PV) generation systems is presented in this paper. The proposed scheme is based on two insulated strings of PV panels, each one feeding a standard two-level three-phase voltage source inverter (VSI). Inverters are connected to grid by a three-phase transformer with the open winding configuration on inverters side. The resulting conversion...
In the distributed AC supply system without control interconnection, the parameters unbalance because of nonuniformity between the unit inverters is inevitable. The supplier unit is difficult to share power properly. Based on the digital control inverter with instantaneous capacitor-current feedback, the affection to power sharing of the filter inductance and equivalent line impedance are analyzed...
A parallel active power filter for harmonic distortion compensation, its signal processing unit, control principle and power stage are described. Power stage of the proposed active filter is realised using three serial inductance, three-phase IGBT based current controlled voltage inverter with two symmetrical capacitors on dc bus. Three independent hysteresis controllers on the base of current references...
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