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Nowadays, the increasing number of non-linear loads influences the grid, causing grid voltage disturbances. These disturbances may be very dangerous for the equipment and can create faults in converter behaviour. However, the right control algorithm can improve the reliability of the work. For a current source rectifier, the finite control set model predictive control has been proposed. This method is very flexible because of the variety of the possible cost function forms. It has been examined under grid voltage disturbed by the higher harmonics and the voltage drop. Simulation results prove the ability to damp the distortions and to ensure the unity power factor. Summing up, the algorithm is a very good solution for use in applications such as battery charging, active power filtering and low-voltage direct current load feeding.

In this paper, simulation of large motor drives with three-level neutral point clamped converters and testing results of converter transformer differential protection are presented. The protected converter transformer is used for supply of active front end converters. The converter transformer itself must be protected by a relay being able to operate with highly distorted signals by higher harmonics. One should be aware that high content of harmonics (2nd, 5th) may cause problem with sensitivity and stabilization of protection. An appropriate simulation model of the converter transformer and three-level neutral point clamped converters with adequate control was developed in MATLAB/Simulink environment. Testing results of transformer differential protection operation for various disturbances are presented.

Este artículo presenta un resultado de investigación financiado con recursos propios en el que se expone un modelo en espacio de estados de un rectificador trifásico controlado active front end. Utilizando este modelo se deriva una ley de control orientado al voltaje (VOC), enfocado en el comportamiento como carga resistiva, factor de potencia unitario, el cual es probado mediante simulación usando el Toolbox SimPowerSystem en Simulink de Matlab®.

This paper presents a comparison between the control system performances of different cranes work at Port Said Container Terminal. These cranes work with different control systems such as DC drive, AC drive and Active Front End drive. Comparison has been done between two drive systems, DC drive and Active Front End drive (AFE). The advantages and disadvantages are discussed and summarized

The area of harmonic line current formation by an active front end was established. The theoretic dependence of boundary characteristic for active front end operation with a set value of reactive power consumed from the network (outputted to the network) was obtained. The operating mode for various tasks on the line current displacement angle relative to the supply voltage, as well as tasks of measuring the active front end output voltage were investigated.

Today there are numerous companies in Iran manufacturing Uninterruptible Power Supplies (UPS). However, in medium and high power range they manufacture online double conversion transformer based UPSs, with thyristor controlled rectifier. In this paper the power topology, control algorithm and experimental results of the first commercial active front end 30 KVA transformerless UPS in Iran is presented.

In this paper the behavior of an Active Front End Converter in the presence of repetitive voltage sags is presented. An overview of the simulation model of the Active Front End is given together with the control principle. Different conditions of repetitive notches are studied and simulation results are presented in this paper.

This paper presents the application of high-power three-level active-front-end rectifiers to regenerate energy in a downhill conveyor system. The selective harmonic elimination method is used to eliminate harmonics 11 and 13, working with very low switching frequency, where six-pulse harmonic orders 6k/spl plusmn/1 are eliminated by the delta-wye connection of the transformer. In this way, the input current at the mains is highly sinusoidal with small harmonics starting at frequencies of order 23 and 25. Resonances have been detected, originated mainly by the capacitances of feeding cables and noneliminated harmonics, which produce high-voltage distortion. Theoretical and field measurements present the problem and the solution by using a specially designed high-pass power filter.

AC drives are increasingly common in pumping applications. However, their operation produces harmonic currents, which can have a number of detrimental effects on system performance. Ian C Evans of Harmonic Solutions considers the role of active front end drives in harmonic mitigation.

This paper investigates the effect of voltage stress on the voltage insulation components inside regenerative Active Front End (AFE) Adjustable Speed Drive (ASD). The paper shows that high potential voltage insulation issue may exist on various components inside the ASD and cause earlier failures under very long cable or multiple drive conditions. A simplified system model to describe this phenomenon is described, the voltage stresses inside the drive under different grounded condition are analyzed, and their conclusions are verified by both simulation and experimental results. It is concluded that a much higher voltage stress may exist in different location of the drive under different grounding systems. Appropriately designing the insulation components is critical to protect the drive.

Non-standard conditions in the power network such as voltage unbalance can negatively affect operation of electric drives. The unbalance can be caused by a failure in the network or by an unbalanced load in the electric vicinity of the affected drive. Unsymmetrical voltages at the input of a voltage source inverter cause pulsations in the DC link voltage when not properly taken care of. This may result in significantly reduced power capabilities and, therefore, limited controllability of the drive. This text deals with the effects of unbalanced voltage supply on the DC-link voltage pulsations, methods to address this problem and the additionally imposed constraints in operating regions of the rectifier.

Using a Variable Frequency Drive, 15kWh battery pack, and Active Front End control, Colorado State University has designed and built a real-world functional test stand to study the effects of attaching a battery power pack to the grid for grid stabilization. This paper describes the design, analysis, and construction of the Grid Attached Storage simulation laboratory. An in-depth discussion of the design, selection and specifications of components including the LCL filter, transformer, grid attachment, line synchronization card, software control, and safety measurements is discussed. The dynamics and control of grid-attached storage can be investigated using this lab. Battery temperatures, charging/discharging cycles, and battery degradation can also be better understood with the use of this system. Second life batteries can be used as well to investigate their characteristics, economical benefits, and quality of use. Using grid interaction, the batteries can work in a variety of ways including: frequency regulation, V2G simulation of opportunity charging, and renewable energy smoothing.Copyright © 2011 by ASME

The paper describes the requirements for fault tolerance in the power systems of dynamically positioned vessels. The short-comings of diode bridge rectifiers in this regard are highlighted. The active front end converter is introduced and a further improvement in fault tolerance is shown to be available from dual active front end. This novel concept gives improved options for reducing the installed thrust or installed generation while continuing to meet classification society rules.

Long belt conveyors have always been a challenge for drive and control applications. There are several methods for the drive to be applied. Depending on the geographical conditions, the material to be transported, the fulfillment of the environmental requirements and the operating methods, a different drive system can and must be supplied. This paper describes the drive system for a down hill conveyor which is mounted between the quarry area and the raw material section of the plant. Because of the operational requirements, the drive is to be adjustable in speed, and capable of regenerating the power on the down hill section. A new technique, the so-called active front end technology, was applied and described in detail. All operating processes nowadays are monitored, with sophisticated control systems. The paper gives a good insight to how the control algorithm was applied and is operating. One of the big advantages proclaimed for this technology is that it is "extremely network friendly". The paper shows in detail, what this means, using measurements and analysis in the network. The paper describes, as well, all the environmental fulfilments with the use of a tube conveyor. The content of the paper would not be complete without having a look into the energy balance, from active power taken out of the network, and the regenerative power fed back into the network. It puts an eye, as well, on the aspect of the operating and the life cycle cost.

In high power applications the problem of ac/dc conversion by four quadrants boost converters, named active front-end (AFE), is critical. Design criteria of these kinds of converters have to consider some aspects like: maximum switching frequency of inverters devices, harmonic currents circulating in the transformers, voltage notches at point of common couple (PCC) and the correct behavior of the AFE as current source. The currents absorbed by such a device are affected by a switching ripple whose characteristics are related to the electrical parameters of the boost converter. In high power handling, where the switching frequency is low, the ripple on line currents can be very dangerous and it produces notches in the node voltages which may cause several problems. The authors propose an innovative parallel system, called synchronous active front-end (SAFE) that well satisfies the trade-off between high dynamic performances and minimum harmonic noise. Moreover, the design criteria for a SAFE, are presented