Optimal Mode Decomposition-Based Analysis of Electromechanical Oscillations of Power Systems Using Synchrophasors

Deyou Yang,Bo Wang,Jin Ma,Lixin Wang,Guowei Cai,Jie Tian

doi:10.1109/access.2020.3032789

Abstract

Synchrophasor-based electromechanical modes extraction offers essential information for monitoring the small-signal stability of power systems without models. This article proposes an optimal mode decomposition (OMD) method for extracting electromechanical modes from noise-contaminated measurement data. In the proposed method, an iterative optimal process based on the Grassman manifold is employed to enhance robustness to measurement noise, such that the fixed low-dimensional subspace using proper orthogonal decomposition (POD) is not required in the proposed method. The proposed method gives a reliable extraction of frequency and damping ratio as well as the mode shape using multichannel wide-area measurement data. The performance of the proposed method is tested using simulated data from the IEEE 4-machine 2-area test system, 16-generator 5-area test system and measured data from a real power system.

Highlights

With the continuous expansion of the power grid, electromechanical oscillation is one of the key factors that affects the stability of power systems and limits the power transfer capacity between different areas
This paper proposes an optimal mode decomposition (OMD) method for extracting electromechanical modes from noise-contaminated measurement data
It is necessary to monitor the electromechanical oscillations after disturbances

Summary

Introduction

With the continuous expansion of the power grid, electromechanical oscillation is one of the key factors that affects the stability of power systems and limits the power transfer capacity between different areas. Damped oscillations may lead to oscillation instability or collapse of the power system. The analysis of electromechanical oscillations is essential for ensuring the security and stability of power systems [1], [2]. The extraction of electromechanical modes (frequency, damping ratio and mode shape), which are used to assess small signal stability, is very meaningful. Electromechanical modes can be obtained by linearizing the nonlinear differential equations of power systems at an equilibrium point. Obtaining a detailed dynamic model for an actual system is not a trivial exercise. The computational burden will dramatically increase with an increase in the model dimension [3]

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