Capacitor Voltage Balancing Control Strategy for Converters in 500kV Sunan UPFC

2018 ◽  
Author(s):  
Deng Kai ◽  
Wang Jun ◽  
Zhu Chao ◽  
Qu Feng ◽  
Chen Xuan
Keyword(s):  
Control Strategy ◽  
Voltage Balancing ◽  
Capacitor Voltage ◽  
Balancing Control

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.

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