Methods for analyzing power system small signal stability

Lin, Dan (2015) Methods for analyzing power system small signal stability. Masters thesis, Memorial University of Newfoundland.

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Abstract

Small disturbance such as load changes will affect stability of power systems. Small signal stability problem refers to the stability problems caused by small disturbances. Power oscillation appears in the system because of the effect of small disturbances. Oscillation's property is the key to analyze the stability of power system. The undamped power oscillation may cause the blackout, such as the power outage of North American Western Interconnected (WSCC) System happened in 1996. In order to learn the oscillation's mode, two methods are applied to analyze the oscillation caused by small disturbances. The first method is referred to as model-based analysis for small signal stability problem. It uses mathematical model to indicate whether the system is stable based on the eigenvalue calculation for the mathematical model. The other method is the measurement-based analysis for power system. This method is more popular for today's power system analysis. It uses real-time synchrophasor measurement collected from Phasor Measurement Units (PMUs) that are installed at various buses to estimate the mode of oscillations based on prony method. This method requires the system to be visible using PMUs. In addition, the mode of oscillation for every bus can be detected with the time stamp. This thesis studies these two methods to analyze different power systems. The advantages of using measurement-based analysis are clearly shown in this research. As the power system is highly dynamic, model-based analysis cannot provide accurate real-time information. However, the challenge for applying measurement-based analysis is to find the optimum locations for installing PMUs so that non-observable area does not exist in the whole system. Case studies using four different power system models are presented throughout the thesis.

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