scholarly journals Analysis of Harmonic Distortion Reduction through Modular Multi-Level Inverter using Nearest Level Modulation (NLM) Control Strategy

2021 ◽  
Vol 4 (1) ◽  
pp. 67-79
Author(s):  
Engr Baqir Ali Shah ◽  
Mazhar Hussain Baloch ◽  
Dr. Amir Mehmood Soomro ◽  
Engr Shafqat Hussain Memon ◽  
Dr. Dur Muhammad Soomro
Keyword(s):  
Control Strategy ◽  
Great Part ◽  
Research Paper ◽  
Control Technique ◽  
Voltage Source ◽  
Stable Operation ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Modulation Techniques ◽  
Harmonic Distortions

The research paper presents the control strategy to reduce THD (Total Harmonic Distortions) losses by the implementation of the Nearest Level Modulation control technique in a Modular Multilevel Converter. Modular Multilevel Converter is found one of the leading technologies in Power Electronics & Control, its applications are very common in HVDC systems, FACTS (Flexible Alternating-current Transmission system), Variable frequency drives and Electric vehicles as well. The power quality of MMC is better and has lesser THD in comparison to conventional converters like 2-level converters with carrier-based modulation techniques. The MMC has been designed with high scalability and has high voltage and power capacity. Sub-module is an integral part of MMC which is built up as an identical and controllable part of it. This converter is also called a controllable voltage source (VSC). Researchers aim to come up with a detailed review of control methods and necessary operations applied to MMC-based systems for HVDC, particularly focusing to control the total harmonic distortions. Power converters use many modulation techniques, but the existing techniques contribute to a great part in switching losses. MMC up to 49 levels, by implementing the Nearest Level Modulation (NLM) technique, is robust and has less complexity for the systems like MMC-HVDC, and the levels control the total harmonic distortions. In this research paper, the reduction of THD by increasing the voltage levels in MMC is comprehensively evaluated. The simulation results in MATLAB/Simulink are used to examine and confirm the proposed control strategy for stable operation of MMC for HVDC application.

Research on the Voltage Balance Strategy of Modular Multilevel Converter

2014 ◽  
Vol 1055 ◽  
pp. 157-160
Author(s):  
Ji Min Jing ◽  
Jing Ze Wang ◽  
Yan Chao Ji
Keyword(s):  
Control Strategies ◽  
Low Frequency ◽  
Voltage Divider ◽  
Voltage Source ◽  
Stable Operation ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Factors Affecting ◽  
Capacitor Voltage ◽  
Voltage Balance

The modular multilevel converter (MMC) does not need clamping devices and multiple independent DC voltage source and has a modular structure which is easy to be extended to any level, share a DC side, easy to direct back to back four-quadrant operation and attracts widespread attention. Due to the use of sub-module MMC suspended on the DC side capacitor voltage divider provides synthetic AC output voltage required voltage level and therefore it is essential to the stable operation of the sub-module capacitor voltage balance of the MMC. In this paper, the factors affecting the MMC sub-module capacitor voltage balancing has been carried out a detailed analysis and this paper focuses on the nominal frequency erupted module capacitor voltage control strategies and the average low frequency sub-module capacitor voltage ripple suppression strategies.

Battery Losses In a MMC for BEVS Application

2018 ◽  
Vol 12 (1) ◽  
pp. 98-109 ◽  
Author(s):  
Adolfo Dannier ◽  
Gianluca Brando ◽  
Ivan Spina ◽  
Diego Iannuzzi
Keyword(s):  
Mathematical Model ◽  
System Architecture ◽  
Electrochemical Cell ◽  
Voltage Source ◽  
Modular Multilevel Converter ◽  
Voltage Reference ◽  
Sinusoidal Voltage ◽  
Current Waveform ◽  
Voltage Source Inverter ◽  
Multilevel Converter

Objective:This paper analyses the Modular Multilevel Converter (MMC) topology, where each individual Sub Module (SM), in half bridge configuration, is directly fed by an elementary electrochemical cell.Methods:The aim is to investigate how the reference voltages influence the cells currents waveforms, determining how the active powers and the losses are distributed among the cells. Considering a 2-level Voltage Source Inverter (VSI) topology working in the same conditions, the ratio between the MMC total cells losses and VSI total cells losses is calculated. After showing the system architecture and mathematical model, the cells current waveform investigation is presented and detailed both for triangular and sinusoidal voltage reference waveform.Results:Finally, the results are critically discussed with particular focus on the comparison between the MMC and the VSI topologies.

scholarly journals Novel Control Strategy for Enhancing Microgrid Operation Connected to Photovoltaic Generation and Energy Storage Systems

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1261
Author(s):  
Dina Emara ◽  
Mohamed Ezzat ◽  
Almoataz Y. Abdelaziz ◽  
Karar Mahmoud ◽  
Matti Lehtonen ◽  
...  
Keyword(s):  
Energy Storage ◽  
Control Strategy ◽  
Voltage Stability ◽  
Storage Systems ◽  
Voltage Source ◽  
Stable Operation ◽  
Energy Storage Systems ◽  
Dc Microgrid ◽  
Photovoltaic Generation ◽  
Dc Voltage

Recently, the penetration of energy storage systems and photovoltaics has been significantly expanded worldwide. In this regard, this paper presents the enhanced operation and control of DC microgrid systems, which are based on photovoltaic modules, battery storage systems, and DC load. DC–DC and DC–AC converters are coordinated and controlled to achieve DC voltage stability in the microgrid. To achieve such an ambitious target, the system is widely operated in two different modes: stand-alone and grid-connected modes. The novel control strategy enables maximum power generation from the photovoltaic system across different techniques for operating the microgrid. Six different cases are simulated and analyzed using the MATLAB/Simulink platform while varying irradiance levels and consequently varying photovoltaic generation. The proposed system achieves voltage and power stability at different load demands. It is illustrated that the grid-tied mode of operation regulated by voltage source converter control offers more stability than the islanded mode. In general, the proposed battery converter control introduces a stable operation and regulated DC voltage but with few voltage spikes. The merit of the integrated DC microgrid with batteries is to attain further flexibility and reliability through balancing power demand and generation. The simulation results also show the system can operate properly in normal or abnormal cases, thanks to the proposed control strategy, which can regulate the voltage stability of the DC bus in the microgrid with energy storage systems and photovoltaics.

scholarly journals A Simple and Novel Precharging Control Strategy for Modular Multilevel Converter

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 170500-170512 ◽  
Author(s):  
Wentao Liu ◽  
Ke-Jun Li ◽  
Zhijie Liu ◽  
Meiyan Wang
Keyword(s):  
Control Strategy ◽  
Modular Multilevel Converter ◽  
Multilevel Converter

scholarly journals A Fault-Tolerant Control Strategy of Modular Multilevel Converter with Sub-Module Faults Based on Neutral Point Compound Shift

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 876 ◽  
Author(s):  
Qinyue Zhu ◽  
Wei Dai ◽  
Lei Guan ◽  
Xitang Tan ◽  
Zhaoyang Li ◽  
...  
Keyword(s):  
Fault Tolerance ◽  
Control Strategy ◽  
Control Method ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Neutral Point ◽  
Modular Multilevel Converter ◽  
Phase Voltage ◽  
Multilevel Converter ◽  
Shift Control

In view of the complex calculation and limited fault tolerance capability of existing neutral point shift control algorithms, this paper studies the fault-tolerant control method for sub-module faults in modular multilevel converters on the basis of neutral point compound shift control strategy. In order to reduce the calculation complexity of shift parameters in the traditional strategy and simplify its implementation, an improved AC side phase voltage vector reconstruction method is proposed, achieving online real-time calculation of the modulation wave adjustment parameters of each phase required for fault-tolerant control. Based on this, a neutral point DC side shift control method is proposed to further improve the fault tolerance capability of the modular multilevel converter (MMC) system by compensating the fault phase voltage with non-fault phase voltage. By means of the compound shift control strategy of the DC side and AC side of the neutral point, an optimal neutral point position is selected to ensure that the MMC system output line voltage is symmetrical and the amplitude is as large as possible after fault-tolerant control. Finally, the effectiveness and feasibility of the proposed control strategy are verified by simulation and low-power MMC experimental system testing.

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