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2024 | Book

Stability Assessment of Power Systems with Multiple Voltage Source Converters

Bifurcation-Theory-Based Methods

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About this book

This book offers a comprehensive assessment of the stability of modern power systems through advanced nonlinear analysis frameworks. It addresses the new challenges to power system stability posed by the anticipated integration of numerous power-electronic-interfaced devices needed to support renewable energy generation. Given the diverse operational timescales associated with controllers for power-electronic-interfaced devices, these devices can have an impact on a wide range of dynamic phenomena, thereby significantly influencing the system's dynamic performance and stability. The methodologies presented effectively manage the significant changes in system dynamics introduced by these devices. This research utilizes nonlinear methodologies, specifically bifurcation theory, to analyse various stability types in such power-electronic-rich systems.

The book adopts a bifurcation-based methodology to evaluate power system stability through detailed examination of each type of instability mechanism. The methodology developed is extended to explore the interactions between multiple types of system stability considering the impacts of different voltage-source-converter controllers and grid strengths. Finally, to reduce the high computational burden imposed by the proposed methodology, a hybrid network model is developed to assess the system stability efficiently.

Stability Assessment of Power Systems with Multiple Voltage Source Converters is of interest to students, researchers, and industry professionals in the field of electrical engineering.

Table of Contents

Frontmatter
Chapter 1. Introduction
Abstract
This thesis adopts bifurcation theory, a nonlinear analysis technique, to investigate various power system stability limits, including small-disturbance rotor-angle stability, resonance stability, converter-driven stability and voltage stability. Power systems are approaching and being operated closer to their stability boundaries to improve their efficiency and to address increasing load demand due to electrification. In addition, with the significant integration of power electronic-interfaced devices, the dynamic response of power systems has become progressively dominated by the characteristics of these components. As the controllers of power electronics operate across a frequency range from several kilohertz down to a few hertz, they can impact a wide variety of dynamic phenomena. This may exacerbate adverse interactions between the power electronics devices and the network, which may, in turn, be detrimental to the stability of the power system. Consequently, there is an increasing necessity to perform comprehensive stability assessments of power systems including multiple converters considering various types of stability simultaneously. This introductory chapter outlines the research topics considered in this thesis. It starts with a description of the definition of power system stability, followed by a discussion on the evolution of modern Voltage Source Converters (VSC) technologies and their impacts on system stability. The chapter then introduces the analytical techniques utilised in this research: bifurcation theory and sensitivity analysis. Following this, a thorough literature review is presented, highlighting the research gaps this thesis addresses and outlining the significant contributions detailed in subsequent chapters.
Youhong Chen
Chapter 2. Power System Modelling and Analysis Techniques
Abstract
This chapter establishes the foundation for the power system modelling and analysis techniques used throughout this thesis. It develops the mathematical models of the power system elements that are employed in various studies conducted in subsequent chapters. These models encompass both the dynamic network model based on ordinary differential equations, where network dynamics are included, and the static network model based on algebraic equations, where network dynamics are neglected. The chapter further presents the power system analysis techniques adopted in this research, specifically modal analysis and bifurcation theory. To demonstrate the effectiveness of bifurcation theory in stability assessments, an example analysis of power system stability based on this theory is included. Finally, brief descriptions of the test networks used throughout the thesis are provided.
Youhong Chen
Chapter 3. Loadability Analysis with Multiple Bifurcations Considered
Abstract
This chapter conducts an extensive assessment of power system loadability based on bifurcation theory with a focus on voltage stability. Initially, the chapter updates the system loadability concept by simultaneously considering various types of bifurcations, namely Saddle-Node Bifurcations (SNB), Limit-Induced Bifurcations (LIB), and Hopf Bifurcations (HB). Five loadability scenarios, developed from this revised concept, are proposed and illustrated using test networks. Building on this updated concept, the chapter proposes a new, multi-stage optimisation framework to improve system loadability that considers the SNB, LIB and HB simultaneously. This framework is aimed at optimising system stability by improving the system's shortest loading margin within the given parameter space.
Youhong Chen
Chapter 4. Analysis of Feasibility Region Boundaries with Consideration of Multiple VSCs
Abstract
This chapter presents a comprehensive investigation based on bifurcation theory into the small-disturbance stability of a power system equipped with multiple Voltage Source Converters (VSCs). It proposes a methodology designed to identify a system’s multi-dimensional feasibility region boundary concerning small-disturbance stability when multiple parameters vary simultaneously. The methodology uses a numerical method with a quasi-random sampling technique, which numerically determines the system's feasibility region boundary in an N-dimensional space. Furthermore, a data-driven model based on interpolation techniques is developed to establish the stopping criterion for the numerical method and to efficiently identify the system feasibility region boundary across N-domains. Building on the data-driven model, this chapter adopts the Spearman correlation coefficient to analyse the system's feasibility boundary. This analysis not only identifies the influential parameters on the system's feasibility region but also reveals the interactions between the VSCs and the network by examining the correlation index values.
Youhong Chen
Chapter 5. Identification of Critical Parameters Affecting System Loadability
Abstract
Having demonstrated the effectiveness of bifurcation theory in analysing the small-disturbance stability and voltage stability of power systems, this chapter conducts a thorough study of power system loadability, jointly considering these types of stability. Utilising a statistical assessment framework similar to that employed in Chapter 4, this chapter identifies the most influential parameters affecting system loadability based on their impacts. The sensitivity studies undertaken assess the influence of various grid strength conditions and converter control schemes on the key parameters identified. Moreover, this developed framework is applied to perform a comprehensive evaluation of the performance of various VSC control schemes in large-scale power systems, encompassing scenarios with both single and multiple VSCs connected.
Youhong Chen
Chapter 6. Analysing System Loadability with Multiple VSCs Using a Hybrid Model
Abstract
This chapter introduces an analysis framework based on a hybrid model for assessing system loadability. The framework significantly reduces the dimensionality of the system model required for assessments while still capturing all essential dynamics. Critical dynamics leading to instability are identified using eigenvalue sensitivity measures combined with participation factor analysis. The effectiveness of this method is demonstrated on a small test network, where it is shown to accurately capture essential dynamics and thereby identify instabilities along the loadability trajectory. Following its demonstration on a small test network, the framework is extensively tested on a large IEEE-39 bus network. Here, various system instabilities are accurately identified using the analysis framework, but with a reduced computational burden.
Youhong Chen
Chapter 7. Conclusions and Future Work
Abstract
This chapter summarises the main conclusions of the research presented in this thesis and offers recommendations for future development of the presented methodologies.
Youhong Chen
8. Correction to: Stability Assessment of Power Systems with Multiple Voltage Source Converters
Youhong Chen
Backmatter
Metadata
Title
Stability Assessment of Power Systems with Multiple Voltage Source Converters
Author
Youhong Chen
Copyright Year
2024
Electronic ISBN
978-3-031-63095-8
Print ISBN
978-3-031-63094-1
DOI
https://doi.org/10.1007/978-3-031-63095-8