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2015 | Buch

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Voltage Control and Protection in Electrical Power Systems

From System Components to Wide-Area Control

verfasst von: Sandro Corsi

Verlag: Springer London

Buchreihe : Advances in Industrial Control

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

Based on the author’s twenty years of experience, this book shows the practicality of modern, conceptually new, wide area voltage control in transmission and distribution smart grids, in detail. Evidence is given of the great advantages of this approach, as well as what can be gained by new control functionalities which modern technologies now available can provide. The distinction between solutions of wide area voltage regulation (V-WAR) and wide area voltage protection (V-WAP) are presented, demonstrating the proper synergy between them when they operate on the same power system as well as the simplicity and effectiveness of the protection solution in this case.

The author provides an overview and detailed descriptions of voltage controls, distinguishing between generalities of underdeveloped, on-field operating applications and modern and available automatic control solutions, which are as yet not sufficiently known or perceived for what they are: practical, high-performance and reliable solutions. At the end of this thorough and complex preliminary analysis the reader sees the true benefits and limitations of more traditional voltage control solutions, and gains an understanding and appreciation of the innovative grid voltage control and protection solutions here proposed; solutions aimed at improving the security, efficiency and quality of electrical power system operation around the globe.

Voltage Control and Protection in Electrical Power Systems: from System Components to Wide Area Control will help to show engineers working in electrical power companies and system operators the significant advantages of new control solutions and will also interest academic control researchers studying ways of increasing power system stability and efficiency.

Inhaltsverzeichnis

Frontmatter

Voltage Control Resources

Frontmatter

1. Relationship Between Voltage and Active and Reactive Powers

Abstract

The analytical link between voltage (V) and reactive power (Q) in electrical lines and loads is presented. Acceptable simplifications of equations are introduced to highlight dominant aspects of the V-Q link, which strongly impacts our understanding of grid voltage phenomena, voltage control, as well as performance required of protection solutions and design characteristics. An essential presentation of the main V-Q relationships in electrical lines often referred to by this book is provided.

Sandro Corsi

2. Equipment for Voltage and Reactive Power Control

Abstract

Chapter 1 explained how voltage support requires reactive power control. In this chapter, we describe in detail the main equipment in power systems that are able to deliver or absorb the reactive power through particular aspects of control as they relate to voltage and reactive power.

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3. Grid Voltage and Reactive Power Control

Abstract

A widespread inadequate control of grid voltage and reactive power has become more critical in recent years due to the general trend by system operators and electrical utilities to operate transmission networks as close as possible to their maximum capacity. The need for suitable control solutions capable of dealing with increased power loads and losses, possible grid contingencies and voltage collapse risks has therefore grown in ever tighter and enmeshed networks. Yet, a lack of real-time, closed-loop, automatic coordination of reactive power resources for network voltage control seems as persistent as it is unjustified.

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Wide Area Voltage Control

Frontmatter

4. Grid Hierarchical Voltage Regulation

Abstract

Hierarchical systems based on HV grid subdivision into areas and on automatic coordination of each area’s reactive power resources aiming to control local voltages have been investigated in Europe (mainly in Italy and France) since 1980. These systems are collectively termed either coordinated voltage regulation (CVR), to highlight the required coordination among area control resources, or they are also called secondary and tertiary voltage regulations (SVR and TVR), to emphasise the different layers of the control hierarchy. Reference studies and applications come from Italy and France, followed by Belgium, Spain and more recently by United States, Brazil, Taiwan, South Korea, Romania and South Africa. An international CIGRE task force investigated the subject and, in 2005, published an extensive report.

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5. Examples of Hierarchical Voltage Control Systems Throughout the World

Abstract

Examples of SVR applications throughout the world are briefly presented here according to information available. At present, real, concrete, wide area operating applications exist in Europe, mostly in Italy and France. Several other applications are in progress in Europe, United States and China. Most of the examples presented here refer mainly to results of studies in countries that have shown a clear interest and trust in SVR applications. Obviously, a complete overview of all the real studies and applications of SVR-TVR is not given in this chapter; many are discussed in other chapters of this book

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6. SVR Dynamic Tests with Contingencies

Abstract

Examples of SVR dynamic performance in some large power systems are briefly presented according to available data. Most of the traces presented come from very detailed simulations, including all the dynamic aspects of interest. A few data also refer to real systems, confirming the results of studies and the correctness of the modelling used.

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7. Economics of Voltage Ancillary Service

Abstract

Voltage service is one of the major ancillary services supporting the operation of a power system. Generators are involved, but so is some grid equipment (as considered in this book). Action occurs mainly on power plant operating controls and at the grid level as well, as made possible by V-WAR.

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8. Voltage Stability

Abstract

Distinguishing voltage stability from the classic power system angle stability problem, as it is generally understood and classified, is the chapter starting point. Evidence is also given to the significant contribution of power system voltage control loops (AVR and SVR) to electromechanical oscillation stability, to counteract the tendency to associate voltage control with voltage stability alone. These preliminary clarifications help us differentiate the voltage instability phenomenon as substantially linked to maximum line loadability while increasing the load. The classic voltage-power (V-P) curves of the Thevenin equivalent circuit are introduced as the main evidence in support of the voltage instability process. The nose tip of such a curve gives the correct information on maximum loadability when a power system’s detailed dynamic model of a considered large or equivalent scheme is used. The dependence of the nose shape on the on-load tap changer (OLTC) and the over-excitation limit (OEL) dynamics, and the load characteristics and differences with or without SVR are clearly evidenced. The fact that voltage instability appears to be strongly influenced by power system dynamics is widely demonstrated with comparisons of different operating conditions of the power system control loops. System voltage collapse as the terminal event of an instability process’s deterioration leading to blackout is described as an irreversible process. Examples of large power system voltage instability followed by voltage collapse are provided. A brief mention of the voltage instability Hopf–saddle-node bifurcation method is also made.

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9. Voltage Instability Indicators

Abstract

In the first section of the chapter, we discuss how to recognise voltage instability using reliable indices, mainly those having real-time performance. The introduction provides a general overview of voltage stability indices (VSI) as proposed in the literature, distinguishing the great amount of VSI that fall into the off-line category from the few belonging to the on-line group that can be properly considered true real-time indicators.

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10. Voltage Control on Distribution Smart Grids

Abstract

Primary cabin (PC) voltage control of a distribution grid that hosts the DG is analysed, assuming a control scheme that includes transformers (TR) with on-load tap changer (OLTC), but also generators and flexible AC transmission systems (FACTS), allowing their reactive power remote control. Therefore, more than one contemporary closed-loop control operates on the same variable (voltage) or on the strictly linked variable (reactive power). These combined efforts require proper coordination among operating control loops that generally have different dynamic performances. Promising proposals of alternative coordinated PC controls, including reactive power flow between HV and MV bus bar control, are presented. They are aimed to a great extent to achieve effective automatic regulation via simple and practical solutions.

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11. Wide Area Voltage Protection

Abstract

The main objectives of EHV wide area voltage protection (V-WAP) are to face voltage instability and to increase power system security. Some innovative and very promising V-WAP control solutions are presented here.

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Backmatter

Titel: Voltage Control and Protection in Electrical Power Systems
verfasst von: Sandro Corsi
Verlag: Springer London
Electronic ISBN: 978-1-4471-6636-8
Print ISBN: 978-1-4471-6635-1
DOI: https://doi.org/10.1007/978-1-4471-6636-8