Model analysis and decouple control strategy of three-phase grid-connected inverter with an LCL filter

作者：Bao Xianwen; Zhuo Fang^*; Tan Peixuan

来源：Journal of Xi'an Jiaotong University, 2014, 48(2): 44-49+110.

DOI：10.7652/xjtuxb201402008

• Active and reactive power controls
• Decouple
• Inverter
• LCL filters
• Renewable energies
• Renewable energy generation
• Synchronous reference frame
• Three-phase grid-connected inverters

The average model of three-phase LCL-type grid-connected inverter in synchronous reference frame is deduced and the existing resonant peaks are emphasized. The influence of damping resistances on resonance peaks is analyzed to reveal some new characteristics of the average model. The conventional single closed-loop control method cannot completely eliminate the coupling terms between D-axis and Q-axis in synchronous reference frame. To break down this limitation, a decouple control strategy is proposed for the three-phase grid-connected inverter with an LCL filter. The essence of the proposed decouple control strategy is to eliminate each coupling term of the LCL filter between D-axis and Q-axis gradually by equivalent transformation of block diagram, then to realize the decoupling process by moving all the decoupling items together to the controller. Simulation and experiments indicate that the proposed control strategy solves coupling problems more effectively compared with the conventional single closed-loop control, and realizes the active and reactive power control independently with satisfactory dynamic performance to technically support the exact power control in renewable energy generation.

• 出版日期2014