scholarly journals Research on an Auto-Optimized Capacitor Voltage Balancing Control Strategy of MMC SM for Renewable Energy HVDC Transmission System

Electronics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 104
Author(s):  
Jianfei Zhao ◽  
Changjiu Kong ◽  
Tingzhang Liu ◽  
Ruihua Li
Keyword(s):  
Control Strategy ◽  
Operating Efficiency ◽  
Switching Frequency ◽  
Sorting Algorithm ◽  
Switching Loss ◽  
Voltage Balancing ◽  
Hvdc Transmission ◽  
High Switching Frequency ◽  
Capacitor Voltage ◽  
Balancing Control

The Modular Multilevel Converter (MMC) is one of the most attractive converter topologies in the High Voltage Direct Current (HVDC) transmission field. The latest widely used sorting method has a low algorithm complexity. It can effectively balance the sub-module (SM) capacitor voltages, but it would cause relatively high switching frequency and power loss. Aiming at the problem that the sub-module (SM) capacitor voltage sorting algorithm has a large switching loss due to the high switching frequency of the device, this paper proposes an auto-optimized capacitor voltage balancing control strategy. Firstly, the topology and operation principle of MMC are analyzed. Secondly, a SM capacitor voltage control method based on the dynamic deviation threshold is proposed. Considering the switch switching state of the SM and the difference between the voltages of each SM, the algorithm can obtain the dynamic deviation valve using the closed-loop control. The method can avoid the unnecessary repeated switching of the Insulated Gate Bipolar Transistor (IGBT) under the premise of ensuring that the capacitance voltages of the SMs are basically the same, which effectively result in reducing the switching frequency of the MMC SM and reducing the switching loss, thereby improving the operating efficiency of the system. Finally aiming at the proposed control strategy, the simulation and experimental verification are carried out which shows that the proposed algorithm can better control the system voltage deviation, reduce the switching loss of the system and improve the stability of the system.

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.

scholarly journals Capacitor voltage balancing control with reducing the average switching frequency in MMC

2019 ◽  
Vol 2019 (16) ◽  
pp. 2375-2380 ◽  
Author(s):  
Shunliang Wang ◽  
Tianqi Liu ◽  
XingChuan Huang ◽  
Yuexiao Yu
Keyword(s):  
Switching Frequency ◽  
Voltage Balancing ◽  
Capacitor Voltage ◽  
Balancing Control

The Control Strategy of Establishing the Voltage of DC Side in MMC

2013 ◽  
Vol 756-759 ◽  
pp. 292-297
Author(s):  
Ming Ma ◽  
Gang Peng ◽  
Jun Wei Hao ◽  
Jing Jing Lu ◽  
Chang Yuan ◽  
...  
Keyword(s):  
Control Strategy ◽  
Balance Control ◽  
Voltage Control ◽  
Switching Frequency ◽  
Switching Loss ◽  
Dc Voltage ◽  
High Switching Frequency ◽  
Voltage Balance ◽  
Dc Voltage Control ◽  
Voltage Balance Control

This paper discusses the establishing method of DC voltage of modular multilevel converter (MMC). Firstly the structure of MMC and the charging principle of sub-modules (SMs) are introduced in order to control the DC voltage of MMC and reduce the switching loss. It is pointed out that the DC voltage control in MMC includes two parts, the DC voltage establishment of system and the voltages control of SMs. For the DC voltage control in system, the control theory is analyzed, and the corresponding control strategy is proposed. Meanwhile an improved voltage balance control strategy for SM is proposed by the improvements of the traditional voltage sorting method to reduce the high switching frequency caused by the blind action of switching devices in the SM control. Finally, the simulation results based on PSCAD/EMTDC show that DC voltage in MMC can run in the rated value steadily, and the switching frequency is reduced significantly.

Sign in / Sign up

Export Citation Format

Share Document