Frequency oscillation events take place occasionally in recent years which are strongly related with AGC (automatic generation control) dynamics. In order to investigate the triggering and influence mechanism of AGC oscillations, this paper establishes the multi-area AGC model containing different types of generating units and AGC control types. Then, the oscillation properties and mode identification between AGC and PFR (primary frequency regulation) modes are expounded in detail. On this basis, the DTA (damping torque analysis) theory is studied for frequency stability analysis as it has a clear physical meaning and can reflect oscillation damping characteristics. Then, the model of DTI (damping torque index) is established conduct mode distinguishing and parameter influence analysis. Finally, the effectiveness and feasibility of the proposed method are verified in case studies and some conclusions are drawn from simulation results.
 

frequency oscillation;damping torque analysis;AGC;PFR;small-signal stability