Grid impedance estimation based on particle swarm optimization

The estimation of grid impedance can be used to improve the control performance of the grid-connected inverter in distributed power generation systems and to achieve islanding detection simultaneously. Particle swarm optimization (PSO) algorithm has been widely studied in parameter identification since it converges fast and has few parameters to be set. The paper proposes a grid impedance estimation method based on PSO. First, the paper establishes the grid impedance equivalent model and introduces the theory of PSO briefly, then it describes the principle of the method to estimate grid impedance, and finally, simulations and analyses of the grid impedance estimation using successive iteration method and PSO algorithm are carried out. Simulation results show that: grid impedance estimation using PSO has higher accuracy with shorter time.