An Overview of Four-Leg Converters: Topologies, Modulations, Control and Applications

Rojas, Félix; Cárdenas, Roberto; Burgos-Mellado, Claudio; Espina, Enrique; Pereda, Javier; Pineda, Cristian; Arancibia, David; Díaz, Matías

doi:10.1109/access.2022.3180746

Cited by 23 publications

(7 citation statements)

References 390 publications

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“…The four-leg inverter topology comprises eight bidirectional power switches, each consisting of transistors and fast diodes connected anti-parallel. This allows for power distribution through three phases, enabling the supply of balanced and/or unbalanced linear or nonlinear loads [19,20]. The working principles of the four-leg inverter using three-dimensional vector space modulation were validated in compliance with IEEE 519-standars to control harmonic distortion in electrical systems [21,22].…”

Section: Methodsmentioning

confidence: 99%

Four-Leg Inverter Based on Three-Dimensional Space Vector Modulation Method for Desired Output Frequency

2024

Teh. vjesn.

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Conventional six-switch inverters, designed for balanced three-phase systems, face challenges in low-voltage networks with mixed single-phase and three-phase loads, leading to voltage imbalances. This imbalance adversely affects equipment, especially protection devices and power electronic converters. The increasing use of power electronic devices in industries with nonlinear loads has driven the adoption of four-leg inverters to handle neutral currents during unbalanced load connections in three-phase networks. This shift introduces challenges in pulse width modulation, particularly in the application of Space Vector Modulation (SVM). This work proposes a novel control strategy using a direct 3D-SVM approach, effectively determining switch states for voltage capacitor balancing and precise output current control. The study's main focus is presenting an advanced control strategy for a four-leg inverter utilizing the 3D-SVM technique to operate efficiently under highly unbalanced loads in distribution networks. The goal is to achieve balanced output voltages and currents under varying load conditions while maintaining the desired variable output frequency. Simulation results validate the proposed control strategy, showing a Total Harmonic Distortion (THD) of output current is 2.06% at 50 Hz and 2.55% at 25 Hz under balanced load, same thing in second case under unbalanced load, the THD is 1.65% at 50 Hz and 2.10% at 25 Hz. with similar under nonlinear load, the THD is 1.94% at 50 Hz and 2.46% at 25 Hz. Importantly, all outcomes fall within IEEE Standard 519-1992 for harmonic limits, highlighting the robustness and reliability of the proposed control approach.

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Section: Methodsmentioning

confidence: 99%

Four-Leg Inverter Based on Three-Dimensional Space Vector Modulation Method for Desired Output Frequency

2024

Teh. vjesn.

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“…Concerning higher frequency oscillations several developments on the device level are of importance: (i) advanced converter topologies, e.g. (reduced switch count) multi-level converters [141], that have inherently improved properties; (ii) advanced control and modulation schemes that improve the power quality of power electronic devices [142].…”

Section: A Oscillatory Interactions Rooted In the Control Systemmentioning

confidence: 99%

Survey of Real-World Grid Incidents–Opportunities, Arising Challenges and Lessons Learned for the Future Converter Dominated Power System

Wachter,

Gröll,

Hagenmeyer

2024

IEEE Open J. Power Electron.

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To reach the climate goals set by national and international institutions, a vast transition of the legacy power system is unavoidable. The necessary integration of distributed, renewable generation devices, which are often interfaced with power electronic converters, has a non-negligible influence on the characteristics of the power grid. This is particularly visible during abnormal grid conditions such as faults. For rotating machines, the fast-timescale reaction to these events is mainly determined by physical properties. However, power electronic devices lack this strong coupling and their behavior is generated by the control and automation system, making them a major field of interest during this transition. The present paper provides a survey of real-world incidents, as for example blackouts or oscillatory incidents, that are discussed with respect to the implications for future converter dominated power grids. For typical cascading outages it is shown, where the increasing penetration of distributed, renewable generation and smart grid technologies can be leveraged to increase the system resilience, e.g. by providing grid services through adequate control design or by enabling microgrid concepts. Further, real-world examples of newly emerging challenges driven by power electronic devices are presented. The mechanisms of control system interactions with the neighboring grid and its inherent complex dependency on various factors is illustrated. Lastly, resulting structural developments such as the changed resonance properties of low voltage grids and the increase of harmonic emissions are exemplified.

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“…However, in a residential context, power is supplied by a low-voltage distribution network, in which several single-phase loads or unbalanced three-phase loads are connected. Under this situation, to allow for increased flexibility and future operation in standalone mode with the capability to handle the zero-sequence components, a four-leg two-level converter with an LCL filter is used as the DC-AC stage to interface the grid with the supply system, compared to the three-leg converter that can only regulate positive and negative sequence components [34]. The grid impedance has been modeled with a configurable three-phase voltage source and lumped impedance with a value corresponding to the line length between the PCC and the nearest transformer in a given low-voltage distribution network.…”

Section: System Descriptionmentioning

confidence: 99%

Comparison of Energy Storage Management Techniques for a Grid-Connected PV- and Battery-Supplied Residential System

Martínez-Caballero,

Kot,

Milczarek

et al. 2023

Electronics

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The use of renewable energy sources (RES) such as wind and solar power is increasing rapidly to meet growing electricity demand. However, the intermittent nature of RES poses a challenge to grid stability. Energy storage (ES) technologies offer a solution by adding flexibility to the system. With the emergence of distributed energy resources (DERs) and the transition to prosumer-based electricity systems, energy management systems (EMSs) have become crucial to coordinate the operation of different devices and optimize system efficiency and functionality. This paper presents an EMS for a residential photovoltaic (PV) and battery system that addresses two different functionalities: energy cost minimization, and self-consumption maximization. The proposed EMS takes into account the operational requirements of the devices and their lower-level controllers. A genetic algorithm (GA) is used to solve the optimization problems, ensuring a desired State of Charge (SOC) at the end of the day based on the next day forecast, without discretizing the SOC transitions allowing a continuous search space. The importance of adhering to the manufacturer’s operating specification to avoid premature battery degradation is highlighted, and a comparative analysis is performed with a simple tariff-driven solution, evaluating total cost, energy exchange, and peak power. Tests are carried out in a detailed model, where Power Electronics Converters (PECs) and their local controllers are considered together with the EMS.

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An Overview of Four-Leg Converters: Topologies, Modulations, Control and Applications

Cited by 23 publications

References 390 publications

Four-Leg Inverter Based on Three-Dimensional Space Vector Modulation Method for Desired Output Frequency

Four-Leg Inverter Based on Three-Dimensional Space Vector Modulation Method for Desired Output Frequency

Survey of Real-World Grid Incidents–Opportunities, Arising Challenges and Lessons Learned for the Future Converter Dominated Power System

Comparison of Energy Storage Management Techniques for a Grid-Connected PV- and Battery-Supplied Residential System

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