Analyzing Delay-Power Relationship of the Grid-Connected Inverters in System Small Signal Stability

Abstract

The paper ahead concentrates on the stability issue of three-phase grid-connected inverters, by considering the delay time of digital control systems. To this aim, at first, it has been shown that the existence of delay influences on system stability improvement. Further, our more detailed studies show that, in terms of stability, there is a relationship between the delay and the power of inverters, called as delay-power relationship for inverters connected to the grid. The principle of the mentioned relationship is based on the fact that more powers lead to lower stability margins, especially at higher frequencies. Finally, simulation results verify the analysis resulted by the impedance-based method.