Grid Interactive Inverter


VSI is the most popular choice for grid integration of renewable energy sources. In the Power Electronics Research Lab at K-state, VSI modeling is being done for better understanding of the issues associated with inverter grid integration. The developed state-space model is a perfect representation of the system in both grid-tied and islanded mode of operation. The dynamics of the system with a PI controller is also studied. The closed loop VSI allows active and reactive power being fed back to the grid.


  • A comprehensive model – The model allows for analysis of the system for all system components.
  • LCL filter modeling – Eigenvalue sensitivity analysis allows obtaining the range of values for optimum system operation.
  • Passive damping – Optimal range of passive damping values can also be obtained using the model. Too low a resistor value results in oscillation in the system and too high a value is associated with more losses and reduced functionality for higher order harmonics.
  • Grid impedance – Weak grid conditions can make the integration of renewable sources difficult. Eigenvalue analysis of the model enables assessing system stability with varying grid impedances.
  • PI parameters – Analysis of eigenvalues of the closed loop models also allow optimum selection of the PI controller parameter values.