Open AccessIndependent‐phase current control of a three‐phase VSC under unbalanced operating conditions
Author(s) -
Shi Xianghua,
Filizadeh Shaahin
Publication year - 2019
Publication title -
the journal of engineering
Language(s) - English
Resource type - Journals
ISSN - 2051-3305
DOI - 10.1049/joe.2018.8768
Subject(s) - control theory (sociology) , integrator , phase locked loop , modular design , three phase , current (fluid) , voltage source , phase (matter) , voltage , power (physics) , computer science , engineering , control (management) , physics , electrical engineering , quantum mechanics , artificial intelligence , operating system
This study presents an independent phase‐current‐control architecture for a three‐phase voltage source converter. It comprises three independent single‐phase phase locked loops (PLLs), and a dual‐loop scheme including an outer loop (responsible for active power and ac voltage control) and three similar inner current control loops. To obtain reliable phase‐tracking, an enhanced second‐order generalised integrator‐based PLL is developed. The phase‐tracking angle is strategically selected from the three PLLs to minimise the impact of imbalance‐induced distortions. To validate the proposed control scheme, extensive simulations are conducted for a 101‐level, 500‐MW, 500‐kV (dc) half‐bridge modular multi‐level converter in PSCAD/EMTDC. The simulation results prove that the proposed scheme enables the system to ride through unbalanced conditions effectively and reliably.