Modal identification using bandpass filters based on an ARX model of transient response

Abstract

The interarea modes of a power system can be identified from a transient response in the frequency data of the phasor measurement units during a power system event. An effective impulse response of the modes can be obtained from the transient response, which contains measurement noise. In this paper, a modal identification method that is insensitive to the measurement noise is proposed using an autoregressive exogenous (ARX) model and bandpass filters. To remove the noise, the effective impulse response is filtered through a combined system of bandpass filters with narrow bandwidths centered on the oscillation frequencies of each mode. Modal identification is fulfilled by estimating the coefficients of the ARX model from the filtered impulse response. The identification accuracy of the proposed method is compared with that of the Prony method with singular value decomposition and discrete Fourier transform method. First, the identification accuracy of the three methods is investigated through simulations on modal spacing and measurement noise. Next, an IEEE 39-bus system is simulated to compare the identification accuracy of the three methods. Finally, the feasibility of the proposed method is demonstrated by identifying interarea modes of power systems in North America from transient responses of their frequency data.