Improved low-voltage ride-through control strategy based on photo-storage synergy
To address issues of the DC-side voltage pumping of the converter caused by the traditional control strategy in the process of the low-voltage ride-through ( LVRT) of photovoltaic system,as well as the problem of passive regulation and hysteretic response in the coordination process of energy storage de-vices,an improved LVRT control strategy based on photo-storage synergy was proposed.Initially,the key reason for the voltage pumping was revealed,that is,the accumulation of unbalanced power on the DC-side of the converter.Subsequently,an adaptive generation module of reference current was constructed in converter with the dual goals of voltage support at the grid-connected point and unbalanced power sup-pression to suppress the generation of unbalanced power by optimizing the reference current of the con-verter during LVRT.Based on these,a super-capacitor with direct power control based on the real-time power difference between the photovoltaic and converter outputs was set up to actively and cooperatively absorb unbalanced power beyond the suppression capacity of converter.The simulation results show that on the premise of ensuring the voltage support of the grid-connected point,the improved LVRT control strategy effectively solves the issue of DC-side voltage increasing of the converter with a faster response and adjust speed through hierarchical control.
low-voltage ride-throughphoto-storage synergyunbalanced powerDC side voltagesuper-capacitors
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