Capacitance minimization in modular multilevel converters: Using model predictive control to inject optimal circulating currents and zero-sequence voltage

2016 ◽  
Author(s):  
C. D. Townsend ◽  
R. Aguilera ◽  
P. Acuna ◽  
G. Konstantinou ◽  
J. Pou ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Multilevel Converters ◽  
Modular Multilevel Converters ◽  
Zero Sequence ◽  
Zero Sequence Voltage ◽  
Circulating Currents

scholarly journals High-power modular multilevel converters: Modeling, modulation and control

2021 ◽  
Author(s):  
Apparao Dekka
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Harmonic Distortion ◽  
Switching Frequency ◽  
Multilevel Converters ◽  
Direct Model ◽  
Modular Multilevel Converters ◽  
Dual Stage ◽  
And Control ◽  
Circulating Currents

THIS dissertation addresses the technical challenges associated with the operation and control of high-power modular multilevel converters. To improve the performance of modular multilevel converter (MMC), a generalized three-phase mathematical model with common-mode voltage (CMV) is proposed. By using the proposed mathematical model, the magnitude of circulating currents, capacitors voltage ripple, and the ripple in DC-link current during balanced and unbalanced operating conditions can be minimized. The modulation scheme and switching frequency are directly affected the output power quality and the performance of the converter and control method. In this dissertation, a novel sampled average and space vector modulation scheme is proposed. These modulation schemes are suitable to control the MMC with any number of submodules (without modifications), operates at low switching frequency, minimizes the ripple in output current and voltage harmonic distortion, and reduces the output filter size. For reliable operation of MMC, the voltage balancing among submodules is mandatory. This dissertation proposes a generalized single-stage balancing approach with reduced current sensors to control the MMC. The proposed balancing approach is suitable to implement with both phase-shifted and level-shifted pulse width modulation schemes. With the proposed approach, it is also possible to control the MMC with half-bridge and three level flying capacitor submodules. Also, an improved balancing approach often referred as the dual-stage balancing approach is proposed to minimize the voltage harmonic distortion and device power losses. This dissertation also proposes a direct model predictive control (D-MPC) approach to minimize the ripple in submodule capacitors voltage. To implement D-MPC approach, a discrete-time model of MMC with CMV is proposed. With the use of proposed model, the D-MPC approach does not require a cost function to minimize the circulating currents. The computational complexity is one of the major issues in the implementation of D-MPC approach for MMC. In this dissertation, a novel reduced computational MPC approaches named as dual-stage D-MPC and indirect model predictive control (I-MPC) approach are proposed. These approaches significantly minimize the computational complexity and, improve the voltage and current waveform quality while operating at the low switching frequency. Finally, the simulation and experimental studies are presented to validate the dynamic and steady-state performance of proposed methodologies. Index Terms • Modular Multilevel Converters. • Capacitors Voltage Balancing. • Pulse Width Modulation Schemes. • Circulating Currents. • Capacitors Voltage Ripple • Direct Model Predictive Control. • Dual-Stage Direct Model Predictive Control. • Indirect Model Predictive Control. • Total Harmonic Distortion.

scholarly journals High-power modular multilevel converters: Modeling, modulation and control

2021 ◽  
Author(s):  
Apparao Dekka
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Harmonic Distortion ◽  
Switching Frequency ◽  
Multilevel Converters ◽  
Direct Model ◽  
Modular Multilevel Converters ◽  
Dual Stage ◽  
And Control ◽  
Circulating Currents

THIS dissertation addresses the technical challenges associated with the operation and control of high-power modular multilevel converters. To improve the performance of modular multilevel converter (MMC), a generalized three-phase mathematical model with common-mode voltage (CMV) is proposed. By using the proposed mathematical model, the magnitude of circulating currents, capacitors voltage ripple, and the ripple in DC-link current during balanced and unbalanced operating conditions can be minimized. The modulation scheme and switching frequency are directly affected the output power quality and the performance of the converter and control method. In this dissertation, a novel sampled average and space vector modulation scheme is proposed. These modulation schemes are suitable to control the MMC with any number of submodules (without modifications), operates at low switching frequency, minimizes the ripple in output current and voltage harmonic distortion, and reduces the output filter size. For reliable operation of MMC, the voltage balancing among submodules is mandatory. This dissertation proposes a generalized single-stage balancing approach with reduced current sensors to control the MMC. The proposed balancing approach is suitable to implement with both phase-shifted and level-shifted pulse width modulation schemes. With the proposed approach, it is also possible to control the MMC with half-bridge and three level flying capacitor submodules. Also, an improved balancing approach often referred as the dual-stage balancing approach is proposed to minimize the voltage harmonic distortion and device power losses. This dissertation also proposes a direct model predictive control (D-MPC) approach to minimize the ripple in submodule capacitors voltage. To implement D-MPC approach, a discrete-time model of MMC with CMV is proposed. With the use of proposed model, the D-MPC approach does not require a cost function to minimize the circulating currents. The computational complexity is one of the major issues in the implementation of D-MPC approach for MMC. In this dissertation, a novel reduced computational MPC approaches named as dual-stage D-MPC and indirect model predictive control (I-MPC) approach are proposed. These approaches significantly minimize the computational complexity and, improve the voltage and current waveform quality while operating at the low switching frequency. Finally, the simulation and experimental studies are presented to validate the dynamic and steady-state performance of proposed methodologies. Index Terms • Modular Multilevel Converters. • Capacitors Voltage Balancing. • Pulse Width Modulation Schemes. • Circulating Currents. • Capacitors Voltage Ripple • Direct Model Predictive Control. • Dual-Stage Direct Model Predictive Control. • Indirect Model Predictive Control. • Total Harmonic Distortion.

scholarly journals Model Predictive Control of Modular Multilevel Converters using Quadratic Programming

2020 ◽  
pp. 1-1
Author(s):  
Jiapeng Yin ◽  
Jose I. Leon ◽  
Marcelo A Perez ◽  
Leopoldo Garcia Franquelo ◽  
Abraham Marquez Alcaide ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Quadratic Programming ◽  
Predictive Control ◽  
Multilevel Converters ◽  
Modular Multilevel Converters

Model Predictive Control of High-Power Modular Multilevel Converters—An Overview

2019 ◽  
Vol 7 (1) ◽  
pp. 168-183 ◽  
Author(s):  
Apparao Dekka ◽  
Bin Wu ◽  
Venkata Yaramasu ◽  
Ricardo Lizana Fuentes ◽  
Navid R. Zargari
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
High Power ◽  
Multilevel Converters ◽  
Modular Multilevel Converters

scholarly journals Disturbance-Observer-Based Model Predictive Control for Battery Energy Storage System Modular Multilevel Converters

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2285 ◽  
Author(s):  
Yantao Liao ◽  
Jun You ◽  
Jun Yang ◽  
Zuo Wang ◽  
Long Jin
Keyword(s):  
Energy Storage ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Current Control ◽  
Multilevel Converters ◽  
Battery Energy Storage ◽  
Circulating Current ◽  
Modular Multilevel Converters ◽  
Ac Current ◽  
Battery Energy

Although the traditional model predictive control (MPC) can theoretically provide AC current and circulating current control for modular multilevel converters (MMCs) in battery energy storage grid-connected systems, it suffers from stability problems due to the power quality of the power grid and model parameter mismatches. A two discrete-time disturbance observers (DOBs)-based MPC strategy is investigated in this paper to solve this problem. The first DOB is used to improve the AC current quality and the second enhances the stability of the circulating current control. The distortion and fluctuation of grid voltage and inductance parameter variation are considered as lump disturbances in the discrete modeling of a MMC. Based on the proposed method, the output prediction is compensated by disturbance estimation to correct the AC current and circulating current errors, which eventually achieve the expected tracking performance. Moreover, the DOBs have a quite low computational cost with minimum order and optimal performance properties. Since the designed DOBs work in parallel with the MPC, the control effect is improved greatly under harmonics, 3-phase unbalance, voltage sag, inductance parameter mismatches and power reversal conditions. Simulation results confirm the validity of the proposed scheme.

Machine Learning Emulation of Model Predictive Control for Modular Multilevel Converters

2020 ◽  
pp. 1-1
Author(s):  
Songda Wang ◽  
Tomislav Dragicevic ◽  
Gustavo Figueiredo Gontijo ◽  
Sanjay K. Chaudhary ◽  
Remus Teodorescu
Keyword(s):  
Machine Learning ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Multilevel Converters ◽  
Modular Multilevel Converters

scholarly journals A Reverse Model Predictive Control Strategy for a Modular Multilevel Converter

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 297 ◽  
Author(s):  
Weide Guan ◽  
Shoudao Huang ◽  
Derong Luo ◽  
Fei Rong
Keyword(s):  
Computational Complexity ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Control Performance ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Computational Burden ◽  
Modular Multilevel Converters ◽  
The Cost ◽  
Fast Dynamic

In recent years, modular multilevel converters (MMCs) have developed rapidly, and are widely used in medium and high voltage applications. Model predictive control (MPC) has attracted wide attention recently, and its advantages include straightforward implementation, fast dynamic response, simple system design, and easy handling of multiple objectives. The main technical challenge of the conventional MPC for MMC is the reduction of computational complexity of the cost function without the reduction of control performance of the system. Some modified MPC scan decrease the computational complexity by evaluating the number of on-state sub-modules (SMs) rather than the number of switching states. However, the computational complexity is still too high for an MMC with a huge number of SMs. A reverse MPC (R-MPC) strategy for MMC was proposed in this paper to further reduce the computational burden by calculating the number of inserted SMs directly, based on the reverse prediction of arm voltages. Thus, the computational burden was independent of the number of SMs in the arm. The control performance of the proposed R-MPC strategy was validated by Matlab/Simulink software and a down-scaled experimental prototype.

scholarly journals Elimination of zero sequence circulating currents in paralleled three‐level T‐type inverters with a model predictive control strategy

2018 ◽  
Vol 11 (15) ◽  
pp. 2573-2581 ◽  
Author(s):  
Xiaodong Wang ◽  
Jianxiao Zou ◽  
Ying Peng ◽  
Chuan Xie ◽  
Kai Li ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Control Strategy ◽  
Zero Sequence ◽  
Circulating Currents
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