Study On The Method Of Out-of-step And Splitting Between Large Regional Grid Based On PMU

With the scale of power systems interconnection increasing, when oscillation occursin interconnected power systems, if there are no effective measures to identify and control,the oscillation will spread and result in blackout. It is an effective measure to split thesystem at proper spots to ensure the stabilization of each subsystem. In this paper, byanalysis of changing characteristics of some electrical parameters when interconnectiongrid is out-of-step, a change-rate of current based initial criterion, which threshold-valuecan be adjusted by real-time sampling-value of PMUs, is propose. By analysis the voltageangles difference of buses, which connect to the tie-lines in interconnection grid, an PMUbased out-of-step criterion is proposed. Furthermore, a method is also proposed to seizeoscillation center based on the apparent impedance when active power on interconnectionlines is zero. After the identification of oscillation center, a dynamic splitting schemebased graph theory is realized.