MMC-Based PV Single-Phase System with Distributed MPPT

Barcellona, Simone; Barresi, Marzio; Piegari, Luigi

doi:10.3390/en13153964

Cited by 13 publications

(22 citation statements)

References 32 publications

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“…The latter voltage, v gm , could be neglected for output current controllers as long as there is no path for the zero-sequence components of those currents. Thus, an equivalent inductor L eq can be defined in (10) to get (11), an equation usually applied to PI or deadbeat controllers to manage the active and reactive power transferred to the grid.…”

Section: Convertermentioning

confidence: 99%

“…In addition, circulating currents may have a 50 Hz component that can be used by the controller to transfer energy from the upper arm to the lower arm or back [17]. The main drawback of the MMC is that an additional 100 Hz negative-sequence component arises in the circulating current when using traditional modulators, Considering the above issues, spreading the PV panels over the sub-modules (SMs) of a modular multilevel converter (MMC) by integrating PV strings directly on converter cells has been recently proposed in [9,10]. This topology, shown later in Figure 3, has nearly the same installation cost than central inverters, achieving better performance, it gets mostly the same power optimization as string converters at a lower cost and it may work in a wider power and voltage range with fewer losses than all previous topologies due to removing DC-DC converters.…”

Section: Introductionmentioning

confidence: 99%

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Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction

et al. 2020

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A new topology has been recently proposed for grid-connected photovoltaic (PV) systems, using modular multilevel converters (MMCs) and distributing PV panels throughout the MMC cells. This topology has two main advantages: it reduces the power losses related to moving the energy into the MMC capacitors from an external source, and it removes the losses and costs related to the DC to DC converters used to track the maximum power point on string converters or central converters, because that task is delegated to MMC cells. However, traditional pulse width modulation (PWM) techniques have many problems when dealing with this application: the distortion at the output increases to unacceptable values when MMC cells target different voltages. This paper proposes a new modulation technique for MMCs with different cell voltages, taking into account the measured cell voltages to generate switching sequences with more accurate timing. It also adapts the modulator sampling period to improve the transitions from level to level, an important issue to reduce the internal circulating currents. The proposed modulation has been validated using simulations that show a consistent behavior in the output distortion throughout a wide operation range, and it also reduces the circulating currents and cuts the conduction losses by half. The behavior of this new topology and this new modulation has been compared to the mainstream topology with external PV panels and also to a fixed carrier modulation.

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Section: Convertermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction

et al. 2020

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“…However, these solutions require the use of multiple transformers. Another approach is based on the use of several submodules, in which each one consists of a two-level half-bridge DC-AC converter, which was designated the modular multilevel converter (MMC) [48][49][50][51]. However, this configuration uses an extensive number of submodules.…”

Section: Introductionmentioning

confidence: 99%

Compensation of Unbalanced Low-Voltage Grids Using a Photovoltaic Generation System with a Dual Four-Leg, Two-Level Inverter

et al. 2022

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In this paper, a grid-connected photovoltaic (PV) generation system is proposed with the purpose of providing support to low-voltage grids, namely through the elimination or attenuation of the grid imbalances. This compensation must consider the load types, which can be either linear or non-linear, and whether the reactive power and current harmonics generated by the non-linear loads need to be compensated in addition to the unbalanced active power. This must be well considered, since the compensation of all aspects requires oversized PV inverters. Thus, the different unbalanced compensation schemes are addressed. Several schemes for the generation of the inverter current references taking into consideration the compensation and load type are presented. For this PV generation system, a dual four-leg, two-level inverter is proposed. It provides full unbalanced compensation owing to the fourth leg of the inverter and also extends the AC voltage, which is important when this compensation is required. To control this inverter, a control scheme for the inverter that considers several compensation factors is proposed. A vector voltage modulator associated with the controller is another aspect that is addressed in the paper. This modulator considers the balance between the DC voltages of the inverters. Several compensation schemes are verified through computational tests. The results validate the effectiveness of the proposed PV generation system.

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“…The main advantages of MLIs are waveforms with lower harmonic content and less total harmonic distortion (THD), which makes possible a reduction of filter sizes, as well as reduced stress due to voltage rate of change (dv/dt) and electromagnetic interference [13]. A relevant application of single-phase inverters is the transformerless integration of photo-voltaic (PV) power generation systems [14,15], where MLI topologies have been proposed recently [16][17][18][19][20]. Other applications of single-phase MLIs can be found in active power filters [21] and electric motor drives [22,23].…”

Section: Introductionmentioning

confidence: 99%

Four-Level Quasi-Nested Inverter Topology for Single-Phase Applications

Reusser

Young

2021

Electronics

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In this paper, a novel four-level single-phase multilevel converter is introduced, consisting of six active switches arranged in a quasi-nested configuration. The proposed topology synthesizes its output voltage levels with respect to a floating neutral point, using four cascaded capacitors with identical voltage levels. The proposed converter contains a reduced number of components compared to the neutral point clamped (NPC) or active-NPC topologies (ANPC) for the same number of output voltage levels, since it does not require diode or active switch clamping to a neutral point. Moreover, no floating capacitors with asymmetric voltage levels are employed, thereby simplifying the capacitor voltage balancing. The switching operation principles, modulation technique and control scheme for supplying a single-phase resistive-inductive load are addressed in detail. The proposed four-level inverter allows generating an additional output voltage level with the same semiconductor count as conventional three-level inverters such as NPC and ANPC which allows a superior waveform quality, with a THDv reduction of 32.69% in comparison the clamped inverters. Experimental tests carried out in a laboratory-scale setup verify the feasibility of the proposed topology.

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MMC-Based PV Single-Phase System with Distributed MPPT

Cited by 13 publications

References 32 publications

Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction

Local Carrier PWM for Modular Multilevel Converters with Distributed PV Cells and Circulating Current Reduction

Compensation of Unbalanced Low-Voltage Grids Using a Photovoltaic Generation System with a Dual Four-Leg, Two-Level Inverter

Four-Level Quasi-Nested Inverter Topology for Single-Phase Applications

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