Simulation Implementation of Voltage Balancing and Circulating Current Control of a Modular Multilevel Converter

2014 ◽  
Author(s):  
Congqi Yin ◽  
J. Yu ◽  
D. Atkinson
Keyword(s):  
Current Control ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Voltage Balancing ◽  
Circulating Current

scholarly journals Circulating Current Suppression Control in Surrogate Network of MMC- HVDC System

2020 ◽  
Vol 8 (6S) ◽  
pp. 29-34
Keyword(s):  
Output Voltage ◽  
Electromagnetic Transients ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Voltage Balancing ◽  
Hvdc System ◽  
Circulating Current ◽  
Capacitor Voltage ◽  
Circulating Currents ◽  
Three Phases

Modular multilevel converter consists of hundreds of submodules (SMs) like half bridge and full bridge converters etc. These hundreds of SMs and electrical nodes poses challenges while computing electromagnetic transients (EMTs). This problem becomes more complex while computed in real-time. To overcome this, an equivalent topology to model MMC arm/valve called surrogate network is utilized. But, the major ambiguity integrated with surrogate network model is SM capacitor voltage balancing. This leads to variation in voltage among the three phases which are parallel and produces circulating current between the three phases. A control circuitry is proposed in this paper to suppress/minimize circulating currents between the phases. Apart from circulating current suppression, the ‘ac’ output voltage is also enhanced at the converter with this proposed controller. Simulation is carried out in RSCAD software using RTDS simulator.

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