Study on the Current-Limiting-Capable Control Strategy for Grid-Connected Three-Phase Four-Leg Inverter in Low-Voltage Network
نویسندگان
چکیده
The three-phase four-leg inverter can produce balanced voltages even with unbalanced loads, yet its controller design is quite complicated. Based on the analysis on time domain equations, a decoupled sequence control strategy for the three-phase four-leg inverter in a low-voltage network is proposed. A negative sequence controller and a zero sequence controller are added to the control strategy besides the positive sequence controller. Furthermore, considering the output limit of the inverter, a current limit design scheme is raised through the analysis on each sequence current in synchronous rotating frame. In the case of asymmetry, the limit value of each sequence current can be adjusted dynamically according to the design scheme. The output currents in each sequence can be controlled and limited for different purposes respectively. Finally, simulation results based on PSCAD/EMTDC V4.5.0 verify the validity of the control strategy.
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