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Due to the low inductance of an LCL-filter, the grid current generated by an LCL-filtered Voltage Source Inverter (VSI) is sensitive to low-order grid-voltage harmonics. This issue is especially tough for the control system with Inverter Current Feedback (ICF), because the grid-current harmonics can freely flow into the filter capacitor without control. To cope with this issue, this paper develops...
The increasing use of nonlinear loads entails serious electrical energy quality problems in power grids. In this regards, the Three-level shunt active power filter (SAPF) is proposed. The considered SAPF is constituted by an AC/DC Three-level NPC inverter. This latter is connected to the point of common coupling (PCC) through a high order filter instead of conventional filter L. Indeed, a new model...
The problem of interfacing a Photovoltaic Generator (PVG) with an electrical three phase grid is addressed in the presence of nonlinear loads. The connection of the PVG to the power grid is done in two stages with both a DC/DC converter and DC/AC multilevel inverter. This latter is based on a Neutral Point Converter (NPC) operating simultaneously as an interfacing system and as a shunt active power...
The single-phase PWM rectifier is one of the converter types applicable for the Plug-in Hybrid Electric Vehicles (PHEVs) chargers. A primary challenge with the single-phase rectifiers is the input alternative power with twice the grid frequency, which should be filtered out properly. The lack of proper filtering leads to significant second-order voltage harmonic at the charger output. This results...
Nowadays many of the distributed generation (DG) sources such as photovoltaic systems are connected to the grid via inverters. One of the main problems of the inverters is the injection of current harmonics to the grid. For attenuating the injected current harmonics, low pass filters such as LCL filter are used in the output of the inverters. The quality of the injected current to the grid has a significant...
This paper deals with power quality increasing problem in power supply systems of industrial enterprises with intensive spread of nonlinear load, including machine-building enterprises. The usage of shunt active filter as a kind of active correction system for power quality increasing is presented in the paper. The proposed algorithm of harmonic determination and elimination for shunt active filter...
This paper proposed two universal active power filter (UAPF) topologies for reactive power and harmonic compensation. The proposed system is a combination of series and shunt active power filters. They are suitable to improve the harmonic distortion in the grid currents and a voltage compensation. The filters are composed of three three-phase converters resulting in nine legs. The first (configuration...
The harmonic disturbance that is caused by the double line frequency ripple power in the single phase AC/DC or DC/AC system. This issue can be eased through the installation of bulky electrolytic capacitors in the dc-link. Unfortunately, such passive filtering approach may inevitably lead to low power density and limited system lifetime. Symmetrical full-bridge circuit uses dc-link capacitors to absorb...
A three-phase voltage source PWM rectifier(VSR) has some shortcomings that can lead to resonance, resulting in system instability problems. A novel multi-loop control strategy and a design of the control structure in synchronous coordinate system for LCL-VSR is proposed in this paper to solve the problem. The strategy belongs to active damping control, which introduces the filter capacitor current-loop...
LCL filters are widely used for grid-connected converters because its superiority over L and LC filters, however the resonance problem produced by these filters requires a more effort in the design process to damp it. Active damping techniques which use the sensed capacitor current are widely used in this regard to solve this problem; however this requires an increase in the number of sensors. Based...
LCL filer has been widely applied in modern grid-connected inverter systems. In this paper, the impacts of LCL filter parameters on the filtering effects of harmonics and the current tracking accuracy of grid-connected inverter are analyzed, and the relationships between the inverter-side and network-side currents of the grid-connected inverter under active and reactive current output situations are...
In this paper, synchronous reference frame theory controlling strategy is presented to generate reference current utilizing four-leg three-phase four-wire Distribution Static Compensator (DSTATCOM). An adaptive hysteresis band current controller is proposed to control the hysteresis bandwidth according to the modulation frequency, supply voltage, DC capacitor voltage and slope of the reference compensator...
This paper presents a novel control system for a five-level diode clamped converter based active power filter. The converter has an auxiliary circuit connected to its DC bus. A model based approach is adopted to design the control system. First, the converter state space model is obtained. Next, a multivariable controller is proposed to stabilize the DC bus capacitor voltages and a backstepping method...
Performances analysis of a modular multilevel converter using two different control strategies is presented. The first approach uses a voltage control with a feedback loop on each individual cell to assure cell's voltage balancing. Nonetheless, this latter can be affected by the total cell's voltage ripple if not compensated. As a consequence, low frequencies are injected in the phase output voltage...
This paper proposes a solution for the minimization of the impact of resonances due to parallel capacitances in the grid. This solution is a combination of two additional (ancillary) services of power electronics converters, namely Virtual Parallel Capacitance Reduction (VPCR) and Virtual Resistive Harmonic Damping (VRHD). VPCR is an ancillary service that lets a power electronics converter generate...
This paper will discuss the design and implementation of an integrated circuit controller for the development of a three phase reactive power compensator. An integrated circuit approach is desired as it provides for a more streamlined and economically advantageous design to reactive power compensation. Various methods are available to compensate reactive power levels utilizing different sources of...
This paper deals with required power electronics interface for a 70 kW microturbine-based distributed Generation system. First, an introduction of microturbine technology and its applications is presented, and then the power electronics interface that is required to transfer microturbine's output power to an islanded local load or an electric power grid is described. Different control strategies for...
An efficient pre-filter based on interleaved DC-DC boost switching converters to mitigate high-frequency harmonics injection to power sources is proposed. The main feature of the pre-filter is to mitigate the ripple of power converters input-current, improving the efficiency of the whole power conversion chain. The pre-filter optimal operating conditions are calculated, and the circuit is modeled...
This work deals with the design and analysis of a controller for a shunt active power filter. The design is based on combined feedforward and feedback actions, the last using odd-harmonic repetitive control, and aims at obtaining good closed-loop performance in spite of the possible frequency variations that may occur in the electrical network. As these changes affect the performance of the controller,...
The paper presents the novel control system for a shunt active power filter (APF) connected to an electrical grid via LCL circuit. Such a circuit constitutes 3rd order low pass filter and almost completely attenuates current ripples from PWM, which are the major drawback of APF connected via inductors. Such a solution requires control that overcomes LCL resonance problem and, at the same time, maximizes...
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