Wide-Area Line Outage Monitoring by Sparse Phasor Measurements

Timely identification of transmission line outages is key to situational awareness and preventing the propagation of disturbed system conditions. Although a line may get disconnected from both ends simultaneously, sequential tripping of the opposite ends of the line is more common regardless of whether the outage is planned or administered by protective relays. This paper proposes a method for line outage monitoring and identifying the sequence of events that a line is undergoing before getting disconnected from both ends. Using the bus impedance matrix, a transfer function is derived to relate the line outage to the variations of phasors collected in the control center. A closed-form solution is put forward to identify the disconnected line based on the weighted sum of squared residuals concept. The proposed method does not require the network to be fully observable, nor does it count on the reception of any fixed set of measurements. As opposed to existing solutions, the method does not rely on power flow derivations, a feature that highly reduces its decision time. High speed, along with the robustness against partial communication network failures and losses of the time synchronization signal, makes the method suitable for real-time applications. Extensive simulations conducted on the IEEE 39-bus and 118-bus test systems demonstrate the superior performance of the proposed method compared to existing ones.