A Cross-Power Spectral Density Method for Locating Oscillation Sources Using Synchrophasor Measurements

This article proposes a new measurement-based approach for locating the sources of forced or poorly damped oscillations in a power system. The approach is based on the concept of cross-correlation in the frequency domain known as cross-power spectral density (CPSD). CPSDs of synchronized voltage magnitude and voltage angle versus active power and reactive power signals obtained by phasor measurement units (PMUs) are computed using fast Fourier transform. The largest positive imaginary part of a CPSD is used as an indicator of the oscillation source. The type of an oscillation source is determined by comparing the spectral densities of active and reactive power. In addition, preprocessing of the signals is performed via variational mode decomposition for extracting the dynamic component of the signals. The proposed approach was able to successfully identify all submitted test cases in the IEEE-NASPI Oscillation Source Location Contest. Several case studies presented in this article highlight the advantages of the proposed approach compared to the state-of-the-art dissipating energy flow method.

I. Introduction

Phasor measurement units (PMUs) [1] find widespread use in power grids in the United States and around the world. These devices report voltage and current measurements, which are synchronized using the GPS signal, at 30 (25) or 60 (50) times per second for systems with nominal frequency of 60 (50) Hz.