Phenomenon of Active Power Consumption by the Inductors in Voltage Source Converters Dominated Power Systems

Accompanied by the increasing penetration of grid-connected voltage source converters (VSCs) in modern power systems, the related oscillatory phenomena are discovered. To analyze the mechanisms of such oscillations, making clear the power exchanging characteristics as well as the power transporting characteristics of various elements in power systems is the basis. The related studies usually regarded that only the resistors in AC grid consume active power during dynamics. However, in this paper, the phenomenon that the inductors will also consume active power during dynamics is found. And what's more, the active power consumed by the inductors may even lead to the instability of system in some cases. To analyze the cause for the found phenomenon, the external characteristics of VSC seen from the grid is concerned, which can be described with a voltage source whose amplitude and frequency are both time-varying. Through analysis in this paper, it is mainly the frequency variation of the equivalent voltage source that bring in the phenomenon. All the results have been validated through the time-domain simulations. The found phenomenon and analysis will update the existing understanding about mechanisms of oscillations related to VSCs.