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Proceedings ArticleDOI

NPC three-level four-legged Shunt Active Power Filter under Non-Sinusoidal Power Supply Conditions

TL;DR: Three-level four-legged active power filter based on neutral-point-clamped (NPC) inverter is presented to fulfill the requirement of the active power filtering function under balanced, unbalance and distorted power supply voltages.
Abstract: Reactive and harmonic currents that are being injected in the power supply by nonlinear loads, cause an increasing deterioration of the power system voltages and currents. Whereas active power filter (APF) have been widely used to overcome this problem and to improve the power quality delivered by the power supply. In this paper, three-level four-legged active power filter based on neutral-point-clamped (NPC) inverter is presented. To fulfill the requirement of the active power filtering function under balanced, unbalance and distorted (including 3rd and 5th harmonics) power supply voltages, A control methods based on the instantaneous power theory have been used and discussed. On the otherside, the inverter switching state control has been achieved based on PWM current controller. The performance of the proposed topology under the used control approach has been finally discussed through the obtained simulation results.
References
More filters
Journal ArticleDOI
TL;DR: This paper comprehensively analyzes the relationship between space-vector modulation and three-phase carrier-based pulse width modulation and shows that all the drawn conclusions are independent of the load type.
Abstract: This paper comprehensively analyzes the relationship between space-vector modulation and three-phase carrier-based pulse width modulation (PWM). The relationships involved, such as the relationship between modulation signals (including zero-sequence component and fundamental components) and space vectors, the relationship between the modulation signals and the space-vector sectors, the relationship between the switching pattern of space-vector modulation and the type of carrier, and the relationship between the distribution of zero vectors and different zero-sequence signal are systematically established. All the relationships provide a bidirectional bridge for the transformation between carrier-based PWM modulators and space-vector modulation modulators. It is shown that all the drawn conclusions are independent of the load type. Furthermore, the implementations of both space-vector modulation and carrier-based PWM in a closed-loop feedback converter are discussed.

1,004 citations


Additional excerpts

  • ...The control of the inverter legs is summarized in two steps as follows [10], [11], [12]....

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Journal ArticleDOI
TL;DR: In this paper, an enhanced current control approach, which seamlessly integrates system harmonic mitigation capabilities with the primary DG power generation function is proposed, which effectively eliminates the impacts of steady-state fundamental current tracking errors in the DG units.
Abstract: The increasing application of nonlinear loads may cause distribution system power quality issues. In order to utilize distributed generation (DG) unit interfacing converters to actively compensate harmonics, this paper proposes an enhanced current control approach, which seamlessly integrates system harmonic mitigation capabilities with the primary DG power generation function. As the proposed current controller has two well-decoupled control branches to independently control fundamental and harmonic DG currents, local nonlinear load harmonic current detection and distribution system harmonic voltage detection are not necessary for the proposed harmonic compensation method. Moreover, a closed-loop power control scheme is employed to directly derive the fundamental current reference without using any phase-locked loops (PLL). The proposed power control scheme effectively eliminates the impacts of steady-state fundamental current tracking errors in the DG units. Thus, an accurate power control is realized even when the harmonic compensation functions are activated. In addition, this paper also briefly discusses the performance of the proposed method when DG unit is connected to a grid with frequency deviation. Simulated and experimental results from a single-phase DG unit validate the correctness of the proposed methods.

220 citations


"NPC three-level four-legged Shunt A..." refers methods in this paper

  • ...Therefore, to overcome this problem, a PLL is used within the control loop [15]....

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Journal ArticleDOI
TL;DR: In this article, a comparative analysis between results from applications of the p-q and the pq-r theories in shunt active power filters for three-phase four-wire systems is presented.
Abstract: This paper presents a comparative analysis between results from applications of the p-q and the p-q-r theories in shunt active power filters for three-phase four-wire systems, discussing aspects related to the influence of the system voltage in the control methods that calculate the compensating currents. It is shown that in some cases, a preprocessing of the system voltage is required if the goal is to achieve sinusoidal compensated currents. On the other hand, when the goal is to compensate zero-sequence current, the need of energy storage elements in the active filter is discussed. In this case, if zero-sequence components are present simultaneously in the system voltage and load current, they produce zero-sequence power flow, and the control methods based on both theories must contain additional calculations to allow the elimination of energy storage elements in the active filter. A control strategy based on the p-q theory is proposed to eliminate the neutral current without the need of energy storage elements, with the advantage of avoiding the extra transformation from alphabeta0 to pqr coordinates that is needed in the p-q-r theory. Simulation results are presented for the purpose of comparing the performance of both control methods.

123 citations


Additional excerpts

  • ...In order to ensure the control of the four-Legged active power filter based four-legs VSI, many control strategies have been proposed [7], [8], [9]....

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Journal ArticleDOI
TL;DR: A novel three-phase parallel grid-connected multilevel inverter topology with a novel switching strategy is proposed to feed a microgrid from renewable energy sources (RES) to overcome the problem of the polluted sinusoidal output in classical inverters and to reduce component count.
Abstract: In this paper, a novel three-phase parallel grid-connected multilevel inverter topology with a novel switching strategy is proposed. This inverter is intended to feed a microgrid from renewable energy sources (RES) to overcome the problem of the polluted sinusoidal output in classical inverters and to reduce component count, particularly for generating a multilevel waveform with a large number of levels. The proposed power converter consists of $n$ two-level $(n+1)$ phase inverters connected in parallel, where $n$ is the number of RES. The more the number of RES, the more the number of voltage levels, the more faithful is the output sinusoidal waveform. In the proposed topology, both voltage pulse width and height are modulated and precalculated by using a pulse width and height modulation so as to reduce the number of switching states (i.e., switching losses) and the total harmonic distortion. The topology is investigated through simulations and validated experimentally with a laboratory prototype. Compliance with the $\text{IEEE 519-1992}$ and $\text{IEC 61000-3-12}$ standards is presented and an exhaustive comparison of the proposed topology is made against the classical cascaded H-bridge topology.

115 citations


"NPC three-level four-legged Shunt A..." refers background in this paper

  • ...electromagnetic interference problems, lower voltage rated switches and ensures smaller Common-mode (CM) voltage, Unfortunately, Three level VSI has a critical disadvantage which is a greater number of power semiconductor switches are needed and therefore, more complicated control and additional costs are required [5], [6]....

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Journal ArticleDOI
TL;DR: In this article, a compensation method using power theory was proposed to improve the stability of a three-phase PWM inverter with respect to the additional poles introduced by the LC part.
Abstract: The demand for three-phase pulsewidth modulation (PWM) inverters in applications such as power control or grid connecting has been on the increase in recent years. Such inverters are connected to the grid via an L filter or an LCL filter to reduce the harmonics caused by the switching. An LCL filter can reduce the harmonics induced by low switching frequency and generates a satisfactory level of grid-side current using a relatively low inductance, as compared to an L filter. The additional poles introduced by the LC part induces resonance in the system, leading to stability problems; this paper presents a compensation method using power theory to improve these issues, so that the performance of the designed LCL filter system can be improved. The effectiveness of the proposed algorithm is verified by simulations and experiments.

112 citations


"NPC three-level four-legged Shunt A..." refers background in this paper

  • ...The rotating speed of pqr coordinates varies according to the voltage space vector system [13], [14]....

    [...]