A New Criterion On Power System Separation

The accidents of loss of ability occur frequently both at home and abroad. When the synchronization loss takes place, disconnecting the interface of out-of-step is considered the main solution to prevent a power system from collapse.In this paper, through analysis of characteristics of electrical parameters of interface tie-line of out-of-step and current separation criteria in the actual field, a new separation criterion is proposed. The power system separation equipment should have the correct functions of initiating the separqation equipment before system losing its synchronism, computing the out-of-step oscillation and capturing the interface (or center ) of out-of-step. The main innovative principles of the new criterion are :initiate the separqation equipment based on the curves characteristics of u cosφ andactive power; compute the time of out-of-step oscillation; with the assiatant of voltage and apparent impedance based method, capturing the interface of out-of-step based on reactive power characteristics. The separation criterion proposed in the paper is easy to be applied in the engineering field and can trip the interface of out-of-step correctly. So the asynchronous oscillation between neighboring interconnected power systems will be eliminated and the widespread outages will be averted.