scholarly journals Performance Comparison of 2L-VSC, 3L-NPC, and 3L-MMC Converter Topologies for Interfacing Grid-Connected Systems

2021 ◽  
Author(s):  
Victor R. F. B. de Souza ◽  
Luciano S. Barros ◽  
Flavio B. Costa

Nowadays, power converters play a fundamental role in the conditioning and processing of active and reactive power, and are directly related to power quality indexes. In this sense, new multi-level converter topologies have been integrated in order to provide higher power processing capacity with lower harmonic distortion, switch stress, heating, and losses. The use of these structures compared to conventional two-level converters is especially suitable for high power of the order of megawatt. Considering the relevance of this approach, this paper presents a comparative performance analysis among the conventional two-level topology (2L-VSC) and two multilevel topologies in a grid-connected system: neutral point clamped (NPC) and modular multilevel converter (MMC). Simulation test results present the impacts on voltages and currents for the switches and the whole system, as well as the evaluation of the total harmonic distortion (THD) in order to highlight the crucial points of each topology for this kind of application.

2018 ◽  
Vol 27 (12) ◽  
pp. 1850187 ◽  
Author(s):  
Rasoul Shalchi Alishah ◽  
Seyed Hossein Hosseini ◽  
Ebrahim Babaei ◽  
Mehran Sabahi ◽  
Jaber Fallah Ardashir

In this paper, a new structure for multilevel converter based on improved H-bridge converter is presented. The proposed topology is a symmetric topology since the values of all voltage sources are equal. The proposed symmetric structure is a general topology which can be extended for any number of voltage levels at output voltage waveform to obtain the least value of total harmonic distortion (THD). Reduction of switching losses, conduction losses, the number of on-state switches in the current path, utilized DC voltage sources, and gate driver circuits are the main advantages of proposed symmetric structures in comparison with other symmetric topologies. All mathematical analysis on the proposed structure is presented in terms of power losses and maximum blocked voltage by switches. The comparison results with other recently presented symmetric topologies and traditional multilevel converter structures are provided. Experimental results for a thirteen-level converter based on presented structure are provided to validate the practicality of the suggested multilevel structure.


Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1292
Author(s):  
Yifan Zhang ◽  
Chushan Li ◽  
David Xu ◽  
Wuhua Li ◽  
Jian Zhang ◽  
...  

Higher-voltage-standard and higher-power-rating aerospace power systems are being investigated intensively in the aerospace industry to address challenges in terms of improving emissions, fuel economy, and also cost. Multilevel converter topologies become attractive because of their higher efficiency under high-voltage and high-switching-frequency conditions. In this paper, an asymmetrical-voltage-level back-to-back multilevel converter is proposed, which consists of a five-level (5L) rectifier stage and a three-level (3L) inverter stage. Based on the comparison, such an asymmetrical back-to-back structure can achieve high efficiency and minimize the converter weight on both rectifier and inverter sides. A compact triple-surface-mounted heatsink structure is designed to realize high density and manufacturable thermal management. This topology and structure are evaluated with a full-rating prototype. According to the evaluation, the achieved power density is 2.61 kVA/kg, which is 30% higher than that of traditional solutions. The efficiency at the rated power of the back-to-back system is 95.8%.


2020 ◽  
Author(s):  
Victor R. F. B. de Souza ◽  
Luciano S. Barros ◽  
Flavio B. Costa

The advancements in power electronics have supported the widespread penetration of wind energy conversion systems (WECS) in electric grids. In this context, power converters have crucial functionality in the control of active and reactive power injection, moreover they are directly related to voltage and current harmonic distortion levels, mechanical and thermal stress that are experienced by the wind turbine. Currently, several topologies have been tested in order to improve the performance and increase the power processing of WECS to support the network demand. Based on the relevance of this issue, this paper presents a performance comparison of a Double Fed Induction Generator(DFIG)-based WECS employing three topologies of back-toback converters: two-level voltage source converter topology (2L-VSC), neutral point clamped (NPC) and modular multilevel converter (MMC). Simulation results present DFIG currents, voltages, torque, speed and the total harmonic distortion (THD), highlighting the performance improvement employing multilevel topologies and the impacts of using each topology.


Author(s):  
Kamel Saleh ◽  
Mark Sumner

This paper introduces a new method to track the saliency of an AC motor fed by a multilevel converter through measuring the dynamic current response of the motor line currents due the IGBT switching actions. The method uses only the fundamental PWM waveform (i.e there is no modification to the operation of the multilevel converter) similar to the fundamental PWM method proposed for a 2-level converter. Simulation results are provided to demonstrate the performance of the complete sensorless speed control of a PM motor driven by such a converter over a wide speed range. Finally the paper introduces a comparison between the 2-level converter and the multilevel converter in terms of the reduction of the Total Harmonic Distortion (THD) using the fundamental PWM method in both cases.


Electronics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 161 ◽  
Author(s):  
Karthikeyan D ◽  
Vijayakumar K ◽  
Jagabar M

In this paper, two different converter topologies for a basic new switched capacitor diode converter with a reduced number of power electronics components, suitable for grid connected photovoltaic applications were proposed. The two different structures of switched diode multilevel converter proposed were: (i) cascaded switched diode and (ii) cascaded switched diode with doubling circuit. The switched-diode multilevel converter was compared with other recent converters. In addition, a new dc offset nearest level modulation technique was proposed. This proposed dc offset technique offers low voltage total harmonic distortion (THD) and high RMS output voltage. The proposed modulation technique was compared with conventional nearest level modulation (NLM) and modified NLM control techniques. The performance of the proposed dc offset modulation technique was implemented using a FPGA Spartan 3E controller and tested with a novel switched capacitor-diode multilevel converter. However, to prove the authenticity of the switched-diode multilevel converter and modulation technique, a laboratory-based prototype model for 7-level and 13-level converters was developed.


Author(s):  
Akram Qashou ◽  
Sufian Yousef ◽  
Abdallah A. Smadi ◽  
Amani A. AlOmari

AbstractThe purpose of this paper is to describe the design of a Hybrid Series Active Power Filter (HSeAPF) system to improve the quality of power on three-phase power distribution grids. The system controls are comprise of Pulse Width Modulation (PWM) based on the Synchronous Reference Frame (SRF) theory, and supported by Phase Locked Loop (PLL) for generating the switching pulses to control a Voltage Source Converter (VSC). The DC link voltage is controlled by Non-Linear Sliding Mode Control (SMC) for faster response and to ensure that it is maintained at a constant value. When this voltage is compared with Proportional Integral (PI), then the improvements made can be shown. The function of HSeAPF control is to eliminate voltage fluctuations, voltage swell/sag, and prevent voltage/current harmonics are produced by both non-linear loads and small inverters connected to the distribution network. A digital Phase Locked Loop that generates frequencies and an oscillating phase-locked output signal controls the voltage. The results from the simulation indicate that the HSeAPF can effectively suppress the dynamic and harmonic reactive power compensation system. Also, the distribution network has a low Total Harmonic Distortion (< 5%), demonstrating that the designed system is efficient, which is an essential requirement when it comes to the IEEE-519 and IEC 61,000–3-6 standards.


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