Analysis of power system oscillations for developing synchrophasor data applications

Electromechanical modes are predominantly determined by the machine rotor angles and speeds, and as a result, they provide the best visibility of such modes. These electromechanical modes are also observable in the network variables such as voltages and line currents, which are measured by PMUs. In this paper, by analyzing the electromechanical modes in the network variables, we can trace the propagation of electromechanical oscillations in the power network following a disturbance. In large power networks with multiple transfer paths across the interconnection it is not always clear how and where the oscillations propagate. Here, we seek to provide a rationale explaining how (the qualitative behavior) and where (transmission lines) network oscillations propagate. We first analyze the oscillations from real PMU data originating from a system-wide disturbance. Applying eigenvalue and sensitivity analysis we provide an analytical framework to understand the nature of the network oscillations. Closed-form expressions for the network sensitivities are provided. The results here important for building reduced models to assess transient stability and the selection of network variables as input signals to damp inter-area mode oscillations.