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Über dieses Buch

This book reports on the latest findings in the application of the wide area measurement systems (WAMS) in the analysis and control of power systems. The book collects new research ideas and achievements including a delay-dependent robust design method, a wide area robust coordination strategy, a hybrid assessment and choice method for wide area signals, a free-weighting matrices method and its application, as well as the online identification methods for low-frequency oscillations. The main original research results of this book are a comprehensive summary of the authors’ latest six-year study. The book will be of interest to academic researchers, R&D engineers and graduate students in power systems who wish to learn the core principles, methods, algorithms, and applications of the WAMS.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
In this chapter, the situation and development of electric interconnected systems are introduced first. The typical stability problems suffered by large interconnected systems are paid attention to. Later, the wide area measurement systems (WAMS) technology and its application in interconnected systems are investigated. A brief summary of the literature describing the approaches to analyze the low frequency oscillation (LFO) phenomenon from system model and measured data is provided.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 2. Theoretical Foundation of Low-Frequency Oscillations

Abstract
In this chapter, the theoretical foundation of low-frequency oscillation (LFO) is introduced. With the increasing utilizations of measurement devices throughout the system, especially the construction of WAMS, the methods which are based on the measured data on-time or off-time have been paid more attention in last few years.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 3. Oscillatory Parameters Computation Based on Improved HHT

Abstract
In the point of operation, the responses of real bulk power system are dynamic and time-varying owing to the influences of load variations, topology changes, and control actions. It is necessary to monitor and calculate the instantaneous oscillatory parameters so as to provide an optimal control strategy. As a nonlinear and nonstationary signal processing approach, Hilbert–Huang transform (HHT) which contains Empirical Mode Decomposition (EMD) and Hilbert transform (HT) has been widely utilized to calculate the amplitudes and frequencies of the single LFO signal. The decomposition ability of EMD provides the condition for HT and HT extends the application fields of EMD. However, the further applications in power system are limited by the inherent shortcomings of HHT, such as the end effects (EEs) and mode-mixing in the process of EMD as well as Gibbs phenomena in traditional HT. In this chapter, the shortcomings of HHT are analyzed and an improved HHT is proposed to determine the oscillatory parameters of single measured signal.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 4. Oscillation Model Identification Based on Nonlinear Hybrid Method (NHM)

Abstract
The oscillatory parameters of each synchronized measured signal can be calculated respectively by improved HHT according to the Chap. 3. However, the improved HHT cannot provide the spatial relationships among all the measured signals. In this chapter, the relative phase calculation algorithm (RPCA) is presented to explore the spatial distribution of the specific oscillation mode. Moreover, the concepts of NCF and AMS are proposed to describe the phase information of specific oscillation mode based on the multi-measured signals.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 5. Identification of Dominant Complex Orthogonal Mode (COM)

Abstract
The essence of LFO can be considered as the energy distribution in time and space. Therefore, characterization of LFO from the aspects of temporal and spatial has great theoretical and practical significance for power system stability analysis.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 6. Basic Framework and Operating Principle of Wide-Area Damping Control

Abstract
With the technical development and cost reduction of power electronics, more and more FACTS devices are being applied into power system especially into modern power system toward smart grid [13]. FACTS devices can conveniently adjust network parameters (e.g., reactance) flexibly and benefit power flow optimization, transmitted power increase, bus voltage stability enhancement, and so on. At the same time, with more and more application of synchronized phasor measurement (PMU) technology, WAMS technology are being applied into power system, which is also one obvious technical feature of the coming smart grid [46]. Therefore, it would be wonderful to construct WAMS-based FACTS supplementary wide-area damping control strategy, that combines the quick and flexible control ability of FACTS devices and the global monitoring ability of WAMS, to prevent the low-frequency oscillation (especial the inter-area oscillation) and enhance the global stability of power system.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 7. Coordinated Design of Local PSSs and Wide-Area Damping Controller

Abstract
The topic on how to coordinate local and wide-area damping control is investigated in this chapter. A sequential design and global optimization (SDGO) method is proposed to coordinate local PSSs and HVDC-WADC simultaneously. The sequential design (SD) is used to determine the time constants of phase-compensation blocks of PSS and HVDC-WADC. Afterward, the global optimization (GO) issued to optimize their control gains. The proposed method focuses on damping all dominant modes including local and inter-area modes to enhance the overall stability of AC/DC interconnected systems.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 8. Robust Coordination of HVDC and FACTS Wide-Area Damping Controllers

Abstract
In this chapter, a wide-area robust coordination method is proposed for HVDC- and FACTS-WADC. It can provide an effective damping on multiple inter-area oscillations excited by various operating conditions. A design procedure is planned as a way of executing the robust coordination for HVDC- and FACTS-WADC. In each step, the WADC design is formulated as a standard robust problem of H 2/H output feedback control. The proposed coordination method is able to consider the output disturbance rejection problem, reduce the control effort, and ensure robustness against model uncertainties.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 9. Assessment and Choice of Input Signals for Multiple Wide-Area Damping Controllers

Abstract
In this chapter, a hybrid method is proposed to assess and select suitable input signals for multiple WADCs. In this method, the residue analysis is used to preselect a set of input signal candidates from many wide-area/local signals, and the relative gain array (RGA) method is used to finally determine the input signals for multiple WADCs.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 10. Free-Weighting Matrix Method for Delay Compensation of Wide-Area Signals

Abstract
In this chapter, in order to improve the power system damping and robustness for the FACTS device, a free-weighting matrices (FWMs) approach-based Lyapunov functional stability theory is proposed to design the FACTS-WADC, which can consider efficiently the effect of signal delay on the control performance. The FWMs approach will be described and the detailed nonlinear simulations on two typical test systems will be performed to evaluate the performance of the proposed SVC-type FACTS-WADC.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 11. Design and Implementation of Delay-Dependent Wide-Area Damping Control for Stability Enhancement of Power Systems

Abstract
In this chapter, the hardware and software design and implementation have been carried out for the discussed wide-area damping control (WADC). First, a hardware-in-the-loop (HIL) test system based on the RT-LAB platform® has been established.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz

Chapter 12. Design and Implementation of Parallel Processing in Embedded PDC Application for FACTS Wide-Area Damping Control

Abstract
In this chapter, the design and implementation of parallel processing in embedded PDC (Phasor Data Concentrator) application for monitoring and stability enhancement of interconnected power system are described and examined.
Yong Li, Dechang Yang, Fang Liu, Yijia Cao, Christian Rehtanz
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