scholarly journals Voltage Balancing Method on Expert System for 51-Level MMC in High Voltage Direct Current Transmission

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Yong Chen ◽  
Xu Zhang
Keyword(s):  
Expert System ◽  
High Voltage ◽  
Direct Current ◽  
Transmission System ◽  
Voltage Source ◽  
Switching Frequency ◽  
Voltage Balancing ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Capacitor Voltage

The Modular Multilevel Converters (MMC) have been a spotlight for the high voltage and high power transmission systems. In the VSC-HVDC (High Voltage Direct Current based on Voltage Source Converter) transmission system, the energy of DC link is stored in the distributed capacitors, and the difference of capacitors in parameters and charge rates causes capacitor voltage balance which affects the safety and stability of HVDC system. A method of MMC based on the expert system for reducing the frequency of the submodules (SMs) of the IGBT switching frequency is proposed. Firstly, MMC with 51 levels for HVDC is designed. Secondly, the nearest level control (NLC) for 51-level MMC is introduced. Thirdly, a modified capacitor voltage balancing method based on expert system for MMC-based HVDC transmission system is proposed. Finally, a simulation platform for 51-level Modular Multilevel Converter is constructed by using MATLAB/SIMULINK. The results indicate that the strategy proposed reduces the switching frequency on the premise of keeping submodule voltage basically identical, which greatly reduces the power losses for MMC-HVDC system.

Fault Diagnosis Simulation of Light High Voltage Direct Current Transmission System

2015 ◽  
Vol 740 ◽  
pp. 466-469
Author(s):  
Xue Hua Jiang
Keyword(s):  
Fault Diagnosis ◽  
High Voltage ◽  
Direct Current ◽  
Practical Method ◽  
Transmission System ◽  
System Structure ◽  
Major Power ◽  
High Voltage Direct Current ◽  
Light System ◽  
Hvdc Light

High Voltage Direct Current (HVDC) system was often the link between major power grids. In order to ensure the safe operation of HVDC, fault diagnosis method was studied. The system structure of HVDC Light system was analyzed, and the normal and fault conditions of the transmission system were simulated in the Matlab platform. This method was very convenient and simple, and it could restore the real situation. The use of simulated waveform could effectively identify the fault types of actual situation, and then it was a flexible, efficient and practical method of fault diagnosis in HVDC Light system.

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