Control strategy to suppress peak current for grid-connected photovoltaic inverter under unbalanced voltage sags
DOI:10.7667/PSPC171205
Key Words:photovoltaic inverter, unbalanced fault  peak current  power fluctuation
Author NameAffiliation
YANG Chaoying State Grid Electric Power Research Institute of Shanxi Electric Power Company, Taiyuan 030001, China 
WANG Jinhao State Grid Electric Power Research Institute of Shanxi Electric Power Company, Taiyuan 030001, China 
YANG Yunlei State Grid Electric Power Research Institute of Shanxi Electric Power Company, Taiyuan 030001, China 
DU Huijie State Grid Electric Power Research Institute of Shanxi Electric Power Company, Taiyuan 030001, China 
XU Yonghai State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University, Beijing 102206, China 
CAO Wei State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University, Beijing 102206, China 
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Abstract:Unbalanced voltage sags often occur during actual power grid operations, causing problem of excessing output peak current, which significantly affects the reliable operation of power grid. This paper first analyzes the mechanism of excessing peak current of grid-connected photovoltaic inverter under unbalanced voltage sags, then a reference current algorithm which takes output peak current into consideration is proposed, adding several adjusting parameters based on the existing reference current algorithm. The reference current algorithm can adjust peak current and power fluctuations. Based on the improved reference current algorithm, an active and reactive coordinate control strategy is proposed, the control strategy effectively solves the overcurrent problem under unbalanced voltage conditions, and expands the output active power of PV system. The simulation models in PSCAD/EMTDC are established to validate the proposed control strategy. This work is supported by National Natural Science Foundation of China (No. 51277069).
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