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Matrix Converters (MCs) are popular due to direct AC/AC conversion applications without the need of bulky, lifetime limited DC links capacitors. In this paper the mostly used MC topologies are explained. Each topology is also modeled and described as well. Moreover, various types of bidirectional switches required for building a MC are studied and compared to show their advantages and drawbacks. As...
Shunt Active Power Filters (APFs) are effective to eliminate harmonic current generated by nonlinear load. Many current control strategies including composite controller are proposed but the current control performance when grid frequency fluctuates is rarely discussed. This paper presents a frequency adaptive strategy for composite controller which can change sampling frequency of the controller...
This paper introduces a low cost high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters. In the proposed UPQC, both shunt and series active power filters (APFs) are developed by using four-switch three-phase inverters so that the number of switching devices in the proposed topology is reduced from twelve in the traditional UPQC down to eight...
The correct current or voltage phase angle of a power electronics equipment is an essential information, especially in those connected to grid as: thyristor rectifiers, active power filters and distributed generation systems. For this reason, up to this day there are several Phase-Locked Loop (PLL) algorithms presented. However, those algorithms usually suffer from unsatisfactory dynamic response...
The switch-mode operation of dc to ac inverters produces undesirable harmonics in the voltage and current outputs. Pulse Width Modulation (PWM) schemes based on Selective Harmonic Elimination (SHE) and carrier-based modulation are commonly used to address the harmonic reduction problem, and to provide adjustable inverter output fundamental components. The implementation of each scheme requires introduction...
Three-phase four-wire Shunt Active Power Filters (SAPFs) can not only compensate the harmonics and reactive power for kinds of unbalanced nonlinear loads, but also suppress the neutral current. According to the disadvantages of conditional control strategies in dq0 frame for APF systems, a control strategy based on abc frame for three-phase four-wire SAPFs is presented. It achieves the control of...
An operating region comparison is performed between a symmetric and an asymmetric CHB Multilevel Shunt Active Power Filter aimed to simultaneously compensate linear and nonlinear currents. The symmetric approach considers that all the power cells injects the same voltage; while the asymmetric case consists in the inclusion of two types of power cells; one of them meant for fundamental reactive power...
A series active filter (SAF) based method for the damping of resonant harmonics created by the LCL-filter of the grid connected PWM-VSI is proposed. Oscillations in multi-megawatt rated high power inverters with LCL-filters are damped with resistors which create undesired power losses typically up to 1% of the rated power of the system. The method stated in this paper overcomes the stability/oscillation...
Power electronic converters are actively involved in many parts of the power grid as active power filters and FACTs devices. They are employed to actively control the absorbed/injected reactive power of the fixed capacitor banks. These devices have the ability to regulate the voltage of distribution systems. In this paper, some novel features are added to the controller of the compensator without...
In this paper the design issues of input electromagnetic interference (EMI) filters for inverter-fed motor drives including motor Common Mode (CM) voltage active compensation are studied. A coordinated design of motor CM-voltage active compensator and input EMI filter allows the drive system to comply with EMC standards and to yield an increased reliability at the same time. Two CM input EMI filters...
Due to the proliferation of distributed power systems, renewable energy sources and systems working in islanding mode, the issue of grid frequency variations has come to be an important topic. In this paper, two single-phase and one three-phase phase-locked loop methods are studied. The resulting PLLs algorithms are completely developed in the discrete plane in order to be directly applied on digitals...
Enhancing power converter reliability is an important issue for multilevel converters. With 2 level topolgies, one IGBT failure leads to the whole system breakdown. Since multilevel converters are featured by a high number of semiconductor switches, it is possible to reshuffle the topology when an IGBT failure occurs. Remedial measurments are then possible and a safe continuity operation after a power...
This paper proposes a three-phase line-interactive Uninterruptible Power Supply (UPS) scheme, which is applied to three-phase four-wire systems, allowing harmonic suppression and reactive power compensation of the load, resulting effective power factor correction. The proposed UPS system is composed of two PWM converters, where one of them is placed in parallel with the load and the other one is placed...
This work presents the development and validation of a model for electric networks supplying nonlinear loads (NLL). The model is based on Neural Networks (NN) and its purpose is the prediction of harmonic currents sank by the loads, in case of supply impedance changes caused by the insertion or releasing of neighboring loads or by the voluntary insertion of filters to reduce such harmonic currents...
Distribution networks commonly utilize three-phase four-wire systems, especially for low-voltage industrial and residential customers. Due to the rapid increase of nonlinear and unbalanced reactive loads in such systems, several power quality issues arise. Among them, line current harmonics, unbalanced load currents, noticeable neutral current and low power-factor. This paper presents a 4-leg shunt...
This paper proposes a Hybrid series active filter (HSeAF) without interfacing transformer. The compensator improves power quality issues of a single phase system. A control algorithm to compensated current harmonics of a nonlinear load to propagate into the single-phase system, while protecting loads from voltage perturbations initiated from the power system is studied. The exclusion of the series...
Distributed generation (DG) interfaced to the grid through power electronic (PE) interface can be used to provide reactive power for voltage stability in a power system they are part of. Furthermore, they can be used to minimize the harmonic issues caused by the PE non-linear loads present at the distribution level. This article investigates the possibility of using a generation side PE interface...
Harmonic impedance is important issue for voltage quality of the microgrid when nonlinear load exists. The distributed generator (DG) unit with different control frame and parameters would have different harmonic impedance. This paper compares the harmonic mitigation property of the current-controlled DG (CC-DG) and voltage-controlled DG (VC-DG) unit. The paper clears following results with analysis...
Current signal monitoring (CSM) can be used as an effective tool for diagnosing broken rotor bars fault in induction motors. In this paper, fault diagnosis and classification based on artificial neural networks (ANNs) is done in two stages. In the first stage, a filter is designed to remove irrelevant fault components (such as noise) of current signals. The coefficients of the filter are obtained...
This paper deals with a single-phase grid-tied photovoltaic system, which can operate, simultaneously, as shunt active power filter and injecting active power into the grid. The photovoltaic system is composed of DC/DC step-up (boost) converter and full-bridge DC-AC converter, performing both reactive power compensation and harmonic current suppression generated by nonlinear loads. The photovoltaic...
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