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Input-series-output-series (ISOS) inverter system is very suitable for high input voltage and high output voltage power conversion applications. If the inverter system topology is applied to the grid-connected application, a large-capacity inverter system can be built with multiple small-capacity standardized inverter modules, which will improve system reliability and simplify system design. For the...
There are today many techniques for controlling active filters on single-phase networks in order to correct the power factor and limit the harmonics consumed at the source. Almost all of these methods are determined for a perfect sinusoidal source. The work developed here concerns the taking into account of a perturbed network, that is to say the presence of voltage harmonics at the connection point...
This paper introduces a new power factor correction scheme for a flyback converter with primary regulation technique, to ideally eliminate the distortion of the ac input current (practically a Total Harmonic Distortion (THD) lower than 5%). The effectiveness of the new control scheme is proved in a 35W driver with universal input range (90VAC∼277VAC). Application target is Solid State Lighting (LED...
A new single-stage three-phase resonant ac-dc quad-active-bridge (QAD) converter is proposed. It uses a new modulation scheme designed for use with a tuned LCL resonant network that achieves unity power factor at both network ports, which leads to reduction in rms bridge currents and conduction loss. The line-frequency phase currents are individually controllable by modulating the ac-side and dc-side...
This paper proposes a three-phase six-inductor double-switch PFC circuit which is suitable for high frequency UPS application. This PFC circuit not only achieves high power factor correction in grid-connected mode of UPS, but also improves bus voltage in battery mode of UPS. This new PFC removes the independent boost design in common UPS and the whole cost can be reduced. The topology structure and...
This paper describes a transformerless STATCOM (Static synchronous compensator) based on the MMCC-SDBC (modular multilevel cascade converter — single-delta bridge-cells) for independent control of positive- and negative-sequence reactive powers. A three-phase 200-V 6-kVA experimental system is designed, constructed and tested to verify the effectiveness of the topology and the control method including...
The total real power injected by distributed renewable energy sources (RES) in the low voltage (LV) grids can cause voltage rise effects during light load scenarios. Integrating RES in microgrid architectures can result in improved power quality of the electrical grid, by avoiding the voltage rise effect from occurring and also by providing ancillary services to the grid. In this paper, a cascaded...
Two-phase residential installations have become very common in Ecuador since different policies prompt the users to replace gas stoves and water heaters by electric appliances. The addition of a second phase to the originally installed single-phase wiring is required to obtain 220Vrms. This fact carries an intrinsic unbalance since single- and two-phase loads coexist. In this paper a topology for...
According to the European grid code, grid-connecting converters should always be connected to the grid under grid voltage unbalance. However, grid voltage unbalance severely affects the stable operation of the converters and leads to the various power issues, such as active power oscillation, DC-link voltage ripple, and overloading. Moreover, under grid voltage unbalance, the active power delivery...
A single phase transformer-less inverter is introduced in this paper. The negative polarities of the input voltage and output terminal have common ground. Therefore, the leakage current problem that is common in PV systems is eliminated naturally. In addition, the proposed inverter has fewer components compared with its counterparts and only one switch conducts during the active states which enhance...
A new single-stage three-phase resonant ac-dc matrix-based converter is proposed. It uses a new modulation scheme designed for use with a tuned LCL resonant network that achieves unity power factor at both network ports, which leads to reduction in rms bridge currents and conduction loss. The line-frequency phase currents are controllable by modulating the ac-side and dc-side switches according to...
This document describes a predictive controller specifically designed to trade-off DC bus voltage regulation error, reactive power compensation and active power curtailment during abnormal operating conditions. The controller proposed evaluates different curtailment alternatives during grid faults and applies the optimal control action that enhances the system performance.
This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages...
Microgrid systems provide benefits to strong, weak and remote power grids. Using multiple sources with differing characteristics and native constraints makes it a challenge to control the microgrid. Compared to the traditional central controller approach, a decentralized microgrid controller architecture has benefits including resiliency to asset and communication failures, which are experimentally...
In this paper, a self-adaptive resonance frequency tracking method is presented. The resonance frequency tracking is used in a LCL-filter-based active power filter to adapt the frequency of the notch filter applied for active resonance damping. By determining the resonance frequency of the LCL-filter and adapting the notch filter frequency, the bandwidth of the notch filter can be decreased, whereby...
In this paper a comparative loss analysis between a cascaded H-bridge (CHB) low-capacitance static compensator (LC-StatCom) with symmetrical I-V characteristics and a conventional CHB StatCom is presented. Effect of the capacitor voltage ripples on switching and conduction losses are determined through theoretical analysis. Simulation-based analyses on a 350-VA three-cell CHB LC-StatCom system are...
This paper proposes a novel discontinuous PWM (DPWM) in order to reduce dc-link current harmonics of a voltage source inverter (VSI) over wide load-power-factor range. This modulation method, which requires only one carrier, contributes to a lifetime extension of smoothing capacitors in a motor drive system. Furthermore, by realizing this modulation method with only one carrier, a high cost hardware...
Compared with the typical three-phase voltage converter, the current source rectifier is very interesting front-end converter because of its buck-type nature and low electromagnetic interferences. However, it includes LC filter, which causes distortions of the grid currents and enhances the reactive power. Proper control algorithm can fix those disadvantages. The chosen option is finite control set...
Continuous voltage compensator was developed to improve power quality issues of distribution lines. It consists of series and shunt transformer connected through static power converters. In this paper, the compensation methods using series and shunt converters were investigated, and manufacturing of actual rating 6.6kV 3MVA prototype was reported.
The paper deals with the current progressive balancing from the target of constant p or constant q component of instantaneous power to symmetrical current target. Referenced current imbalance depends on the operation mode and whether the current reaches the limit. The fixed p component of power is selected for the inverter operation mode. The fixed q component of power is selected for the rectifier...
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