scholarly journals Circulating Current Suppression Strategy of Modular Multilevel Converter Based on Model Predictive Control

2021 ◽  
Vol 261 ◽  
pp. 01035
Author(s):  
kang Liu ◽  
Guige Gao

Modular Multilevel Converter (MMC) has the characteristics of high voltage level and low switching frequency. The traditional modular multilevel converter circulating current control strategy mostly adopts the PI control principle, and the parameter setting is complicated and the accuracy is not high, and the control process is more difficult. Model predictive control strategy is the optimal control method based on the model in the existing time domain. This paper proposes a Model Predictive Control (MPC) method based on carrier phase-shifted pulse width modulation (PSC-PWM) to suppress the circulating current, and output the optimal modulation wave through model prediction. Compared with the traditional control strategy, this strategy is simple to implement, does not require complex tuning calculations, and combines with the traditional capacitor voltage equalization strategy to obtain the output modulation wave. A 7-level MMC simulation control system is built in MATLAB / SIMLINK to verify the theory, comparing with existing control methods, it can be concluded that the proposed method has high calculation efficiency, good control accuracy and strong robustness.

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1861 ◽  
Author(s):  
Zhi Wu ◽  
Jiawei Chu ◽  
Wei Gu ◽  
Qiang Huang ◽  
Liang Chen ◽  
...  

In this paper a hybrid modulated model predictive control (HM2PC) strategy for modular-multilevel-converter (MMC) multi-terminal direct current (MTDC) systems is proposed for supplying power to passive networks or weak AC systems, with the control objectives of maintaining the DC voltage, voltage stability and power balance of the proposed system. The proposed strategy preserves the desired characteristics of conventional model predictive control method based on finite control set (FCS-MPC) methods, but deals with high switching frequency, circulating current and steady-state error in a superior way by introducing the calculation of the optimal output voltage level in each bridge arm and the specific duty cycle in each Sub-Module (SM), both of which are well-suited for the control of the MMC system. In addition, an improved multi-point DC voltage control strategy based on active power balanced control is proposed for an MMC-MTDC system supplying power to passive networks or weak AC systems, with the control objective of coordinating the power balance between different stations. An MMC-HVDC simulation model including four stations has been established on MATLAB/Simulink (r2014b MathWorks, Natick, MA, USA). Simulations were performed to validate the feasibility of the proposed control strategy under both steady and transient states. The simulation results prove that the strategy can suppress oscillations in the MMC-MTDC system caused by AC side faults, and that the system can continue functioning if any one of the converters are tripped from the MMC-MTDC network.


Author(s):  
Rahul Jaiswal ◽  
◽  
Anshul Agarwal ◽  
Richa Negi ◽  
Abhishek Vikram ◽  
...  

This article represents the torque ripple performance of modular multilevel converter (MMC) fed brushless dc (BLDC) motor using different current control technique. For reducing the ripple current in BLDC motor, a phase-modulated model predictive control (PMMPC) technique has been proposed. The stator ripple current is almost negligible using PMMPC. This PMMPC current control method is a significant minimization of torque ripple in BLDC motor. A comparative torque ripple behaviour of MMC fed BLDC motor has been done using phase-modulated model predictive control, model predictive control (MPC) and proportional integral (PI) control at different switching frequency. It has been observed that a PMMPC current control technique is more efficient as compared to the MPC as well as PI current control technique. It has also been observed that the torque ripple performance is improved while using PMMPC as compared to the MPC and PI controller. Simulation results have been verified with the help of experimental result and these results are obtained in good agreement to the simulated results.


Author(s):  
Rashmi Ranjan Behera ◽  
Amarnath Thakur

<p>This paper proposes the grid application of modified three-phase topology of Modular Multilevel Converter (MMC) using finite-control-set predictive control. This topology has reduced number of switch counts compared to the conventional MMC, eliminates the problem of circulating current and having higher efficiency. A single dc source is required to produce sinusoidal outputs. The number of sub-modules (SMs) in this topology is half of the SMs required in case of MMC, in addition to a single H-bride circuit per phase. The finite-control-set predictive current control scheme for the grid connected dc source through the Hybrid Modular Multilevel Converter (HMMC). This controller controls the desired real and reactive power demand of the grid instantaneously. The simulation study of a three phase grid connected system has been done in Matlab/Simulink and the results are provided for the different real and reactive power demands, to validate the concepts.</p>


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