Doctoral Dissertations

Date of Award

8-2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Electrical Engineering

Major Professor

Kai Sun

Committee Members

Kai Sun, Fangxing Fran Li, Hector Pulgar, Zhenbo Wang

Abstract

This work investigates the linear and nonlinear participation factors in power system oscillations, introducing novel model-based and measurement-based approaches for stability analysis.

From the measurement perspective, this research proposes a method for estimating participation factors from generator response measurements under diverse disturbances. The devised technique computes extended participation factors that align precisely with model-based factors, given that the measured responses satisfy an ideally symmetric condition. The symmetric condition is further relaxed by identifying a coordinate transformation from the original measurement space to an optimally symmetric space, thereby achieving the ideal estimation of participation factors from measurements alone. The effectiveness of the proposed approach is demonstrated comprehensively on a two-area system before being tested on a 48-machine power system from the Northeast Power Coordinating Council (NPCC). Given that measurement-based PFs often necessitate considerable data and a black-box system model, the study also proposes response-based PFs for system application, including Electromagnetic Transients (EMT) simulations.

Additionally, this research introduces an Extended Prony Analysis method for measurement-based modal analysis. Drawing upon normal form theory, it juxtaposes analyses on transient and post-transient waveforms, distinguishing resonance modes triggered by near-resonance conditions from natural modes. This method provides more precise modal properties than traditional Prony Analysis, particularly in the case of near-resonance disturbances.

From the model-based perspective, this research scrutinizes the limitations of existing nonlinear PFs, advocating for Time-Variant Nonlinear Participation Factor (TNPF). The relationships between PFs and NPFs are examined in detail from three aspects: perturbation amplitude, time dimension, and nonlinear mode. Additionally, the uniqueness of linear and nonlinear PFs is proven by introducing scaling factors. To bridge the discontinuity between linear and nonlinear PFs, two steps are taken: introducing a time decaying factor to address perturbation amplitude and time dimension, and defining a nonlinear mode via convolution, considering the influence from resonances. The resulting TNPF is presented, with its efficacy demonstrated through a case study.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS