Static synchronous compensators(STATCOM)can be used as a reactive power compensation for induction motor(IM)loads due to its effective control and good compensation.Terminal voltage control(TVC)in a STATCOM has a great influence on voltage dynamics which is a significant concern in a system with many IM loads.This paper investigates the interaction between IM loads and TVC in a STATCOM under weak grid conditions from the viewpoint of active and reactive power flow.A corresponding induction machine model is proposed,based on which the interaction mechanism between IM loads and TVC in a STATCOM can be intuitively understood.It is shown that the negative damping component provided by TVC in a STATCOM can lead to system oscillation instability.Grid strength and the inertia constant of the induction machine affect the extent of such interaction.Time-domain simulation results of IM loads connected to an infinite system through a long transmission line,with STATCOM compensation implemented in MATLAB/Simulink,validate the correctness of the analyses.
