scholarly journals Study of start-up decoupling controller for modular multilevel converter

2021 ◽  
Vol 261 ◽  
pp. 01026
Author(s):  
Xinlin Zhang ◽  
Yanchi Zhang ◽  
Da Xie ◽  
Bowen Zhao
Keyword(s):  
Power Systems ◽  
Pulse Width Modulation ◽  
Control Method ◽  
Switching Function ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Simulation Experiments ◽  
Multilevel Converters ◽  
Start Up ◽  
Modular Multilevel Converters

Modular multilevel converters are widely used in power systems because of their significant advantages. In this paper, a dynamic mathematical model is established by analyzing the topology, operating principle and switching function of the modular multilevel converter, so as to construct an inner and outer loop decoupling controller in dq coordinates. The carrier phase-shift pulse-width modulation is selected to control the sub-module operation, and the uncontrolled pre-charging method is adopted to charge the sub-module. Finally, simulation experiments are carried out in MATLAB/Simulink, and the results show that the control method achieves smooth start-up of the modular multilevel converter.

scholarly journals A Modified One-Cycle-Control Method for Modular Multilevel Converters

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 157 ◽  
Author(s):  
Xu Tian ◽  
Yue Ma ◽  
Jintao Yu ◽  
Cong Wang ◽  
Hong Cheng
Keyword(s):  
Simple Structure ◽  
Pulse Width Modulation ◽  
Reactive Power ◽  
Control Method ◽  
Supply Voltage ◽  
Multilevel Converter ◽  
Grid Environment ◽  
Multilevel Converters ◽  
Modular Multilevel Converters ◽  
Drive Signals

In this paper, a new One-Cycle-Control (OCC) method is designed for a modular multilevel converter (MMC) based on the principle of the equivalent resistance constant. The proposed controller has a simple structure and a small amount of calculation by cancelling the current inner loop proportional integral (PI) controller and the inverse transform in the traditional direct-quadrature (DQ) control. Compared to the traditional OCC controller, the new one separates the control method from the modulation strategy, making it possible to use not only carrier-based pulse-width modulation (PWM), but also nearest level modulation PWM to generate drive signals. Besides, the independent control of the active and the reactive power is implemented by injecting a reference current with the same phase of the supply voltage or a reference current which lags the supply voltage by π/2 into the controller, so the converter can operate in four quadrants and it can work in either a grid-connect or off-grid environment. The feasibility and the performance of the proposed OCC method have been validated by both the simulation under the MATLAB/SIMULINK (R2012a) environment and experimental results.

scholarly journals Novel Uninterruptible Phase-Separation Passing and Power Quality Compensation Scheme Based on Modular Multilevel Converter for Double-Track Electrified Railway

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 738
Author(s):  
Xu Tian ◽  
Xingcheng Li ◽  
Zibo Zhou
Keyword(s):  
Phase Separation ◽  
Power Systems ◽  
Power Quality ◽  
Control Method ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Electrified Railway ◽  
Uninterruptible Power ◽  
Negative Sequence Current ◽  
Double Track

Over-voltage and over-current problems of locomotives when passing phase separation and negative sequence current penetration seriously influence the safety of double-track electrified railway and public power systems. In order to solve these problems, this paper proposes a novel uninterruptible power supply phase separation passing and power quality compensation (UPSP-PQC) scheme for double-track electrified railway. Three working modes of UPSP-PQC are put forward, including uninterruptible phase separation passing mode, power quality compensation mode and uninterruptible phase separation passing priority, and power quality compensation optimum mode. A three-leg modular multilevel converter (MMC) topology of UPSP-PQC is proposed and the corresponding control strategy has been studied. PSCAD/EMTDC simulation is performed to verify the correctness and effectiveness of the proposed scheme and its control method.

A Review on Designand Control Methods of Modular Multilevel Converter

2016 ◽  
Vol 7 (3) ◽  
pp. 863
Author(s):  
Ramya G ◽  
Ramaprabha R
Keyword(s):  
High Voltage ◽  
High Efficiency ◽  
Motor Drives ◽  
Voltage Source ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Power Sources ◽  
Modular Multilevel Converters ◽  
Converter Topology

Modular multilevel converters (MMC) are an emerging voltage source converter topology suitable for many applications. Due to abundant utilization of HVDC power transmission, the modular multilevel converter has become popular converter type to be used in high voltage applications. Other applications include interfacing renewable energy power sources to the grid and motor drives. Modular multilevel converters are beneficial for high voltage and high power motor drives because of the properties of this converter topology, such as, low distortion, high efficiency, etc. For the past few years significant research has been carried out to address the technical challenges associated with operation and voltage balancing of MMC. In this paper, a detailed technical review on the control strategies is presented for ready reference.

scholarly journals Switching Loss Balancing Technique for Modular Multilevel Converters Operated by Model Predictive Control Method

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1175
Author(s):  
Nguyen ◽  
Kwak
Keyword(s):  
Control Method ◽  
Selection Process ◽  
Switching Frequency ◽  
Sorting Algorithm ◽  
Modular Multilevel Converter ◽  
Switching Loss ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
High Switching Frequency ◽  
Capacitor Voltage

The sorting algorithm is the most widely accepted capacitor voltage balancing strategy for a modular multilevel converter. This strategy offers to keep the balance among submodule capacitor voltages under all of the modular multilevel converter working conditions. However, this method generates unnecessary switching transitions in submodules, which results in high switching frequency and switching loss, and uneven distribution of switching transitions and switching loss among submodules (SMs). In this paper, a simplified switching loss balancing control strategy was proposed in order to handle these issues. The proposed approach adjusted the submodule selection process of the sorting algorithm by taking into consideration the number of switching transitions in addition to the capacitor voltages. Even distribution of switching transitions and switching loss was achieved, and the average switching loss was reduced at the cost of slightly increasing the capacitor voltage fluctuations. The effectiveness of the proposed approach was verified through both simulation and experimental results.

A Novel Modulation Method for Modular Multilevel Converters

2014 ◽  
Vol 538 ◽  
pp. 239-242
Author(s):  
Hao Wu ◽  
Ping Wang
Keyword(s):  
Power Electronics ◽  
Modulation Method ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Modular Multilevel Converters

Modular Multilevel has been widely applied in Flexible HVDC, electric locomotives and PET(Power Electronics Transformers). The modulation method is important for the converter performance. This paper presents an improved modulation method for Modular Multilevel Converter.

scholarly journals Lifetime and reliability improvements in modular multilevel converters using controlled circulating current

2021 ◽  
Author(s):  
Nasiru B. Kadandani ◽  
Mohamed Dahidah ◽  
Salaheddine Ethni ◽  
Musbahu Muhammad
Keyword(s):  
Control Method ◽  
Semiconductor Devices ◽  
Junction Temperature ◽  
Multilevel Converters ◽  
Control Approach ◽  
Circulating Current ◽  
Inherent Feature ◽  
Modular Multilevel Converters ◽  
Current Loading ◽  
Laboratory Prototype

AbstractCirculating current has been an inherent feature of modular multilevel converters (MMC), which results in second-order harmonics on the arms currents. If not properly controlled, the circulating current can affect the lifetime and reliability of a converter by increasing the current loading, loss distribution, and junction temperature of its semiconductor devices. This paper proposes controlled circulating current injection as a means of improving the lifetime and reliability of an MMC. The proposed method involves modifying the reference modulating signals of the converter arms to include the controlled differential voltage as an offset. The junction temperature of the semiconductor devices obtained from an electro-thermal simulation is processed to deduce the lifetime and reliability of the converter. The obtained results are benchmarked against a case where the control method is not incorporated. The incorporation of the proposed control method results in a 68.25% increase in the expected lifetime of the converter and a 3.06% increase on its reliability index. Experimental results of a scaled down laboratory prototype validate the effectiveness of the proposed control approach.

scholarly journals A Fast, Decentralized, Self-Aligned Carrier Method for Multicellular Converters

2020 ◽  
Vol 11 (1) ◽  
pp. 137
Author(s):  
Quoc Dung Phan ◽  
Guillaume Gateau ◽  
Phu Cong Nguyen ◽  
Marc Cousineau ◽  
Huu Phuc To ◽  
...  
Keyword(s):  
Conventional Method ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Iteration Process ◽  
Cell Number ◽  
Index Number ◽  
Multilevel Converter ◽  
Start Up ◽  
Multiphase Converters ◽  
Number Of Cells

This paper proposes a fast, decentralized method for self-aligning the carriers of a multiphase/multilevel converter operating on the basis of phase-shifted pulse width modulation or level-shifted pulse width modulation. In the proposed method, each cell of the converter synchronizes and updates simultaneously its own carrier angle or carrier level based on the information shared with its neighboring cell, such as its angle/level, its index number, and the total number of activated cells of the converter. Different from the conventional decentralized method (with basic and modified updating rules), which requires some conditions in terms of cell number and initial carrier angles to start up and operate properly, the proposed method can be applied to the system with any number of cells and does not require special conditions of initial carrier angles. Further, while the conventional method needs an iteration process to adjust the inter-carrier phase-shifts and can be applied only to a multiphase converter which uses phase-shifted pulse width modulation, the proposed method offers an accurate and fast alignment of phases (for phase-shifted pulse width modulation) or levels (for level-shifted pulse width modulation) and thus can be applied to both multiphase and multilevel converter types. The simulations and the experimental results are presented in detail to show the validity and the effectiveness of the proposed methods. Further, thorough simulations on multiphase converters with different number of cells also show that the proposed method is much faster than the conventional method in both configuration and reconfiguration processes, especially in case the system has a large number of cells.

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