Stability and power quality control of parallel inverters in weak current network

Abstract

In the new energy power generation system,the inverter is connected to the grid in parallel,which expands the grid capacity. In addition,due to the existence of grid impedance,the stability of the inverter is reduced and the difficulty of power quality governance in the load increases. The problem of power quality governance of parallel inverter in weak current network is studied. Firstly,H repetitive control combined with voltage feedforward is used as the current inner loop control strategy and the stability performance of single and multiple parallel inverters in weak current network is analyzed. The composite strategy of feedforward channel series complex filter and forward channel series lead correction link is adopted to improve the stability of inverter. Secondly,the current detection algorithm is used to separate the unbalanced,harmonic and reactive currents in the load,which solves the governance of power quality problems caused by unbalanced,nonlinear and reactive loadd. Finally,the simulation experiment is carried out in Simulink. The simulation results show that the power quality problems of multiple loads under the condition of weak power grid can be solved by parallel inverter.

Keywords

• parallel inverter
• power quality
• stability
• current detection
• weak current network
• h repetitive control