Low Frequency Oscillation Analysis for Dynamic Performance of Power Systems

Undamped low frequency oscillations (LFOs) may lead to system collapse. LFOs is closed to the small-signal stability, and traditionally analyzed using model-based method. New measurement-based identification methods are presented in the last decades based on phasor measurement units (PMUs). In this paper, the drawbacks of the model-based techniques for the LFOs analysis are investigated. Firstly, a three-area test system is modified in two configurations: string and ring for LFOs analysis purposes. The modified system has three local area modes and two interarea modes. The impacts of the load changes and topology changes on the electromechanical eigenvalues, observability, controllability, and modal shape are investigated. The results show that electromechanical oscillation modes are highly affected by the load and topologies. The damping controller based on model-based algorithm may inject negative damping if the topology of the system is changed. The system is modeled in differential-algebraic equation set (DAEs) and conducted in MATLAB/Coding environment.