Electric Power Substations Engineering

Edited by John D. McDonald. Published by CRC Press. 2003. ISBN: 0849317037.

The book begins with the introductory chapter "How a Substation Happens." In this chapter we learn of the importance of the public consultative process for the planning of new substations. While the chapter is extremely brief, it discusses issues on determining needs, budgeting, financing, and traditional and innovative substation design. Concepts in site acquisition and design, construction, and commissioning process are also treated. A flowchart illustrating the steps involved in establishing a new substation provides a good summary of the chapter.

Chapter 2, on "Gas-Insulated Substations," starts with a section devoted to and its properties. The main section of this chapter, "Construction and Service Life," discusses in some detail major components of the substation including the circuit breaker, current and voltage transformers, disconnect switches, ground switch, and bus. Air, cable, and transformer connections are also discussed. Surge arresters, control and gas monitoring systems, electrical arrangements, grounding, and testing and maintenance aspects are also discussed. The section concludes with a discussion of the economics of GIS.

Under the title "Air-Insulated Substations—Bus/Switching Configurations," Chapter 3 is devoted to a thorough discussion of the six configurations and a comparison based on economics and reliability considerations. The configurations discussed include single bus; double bus, double breaker; main and transfer bus; double bus, single breaker; ring bus; and the breaker-and-a-half arrangements. A comparison of configurations table concludes the chapter.

In Chapter 4, "High-Voltage Switching Equipment" is explained, beginning with a discussion of the impact of ambient conditions, such as temperature and altitude, on equipment design. The chapter offers discussions of purpose, features, and operational considerations for equipment such as disconnect switches, load break switches, high-speed grounding switches, power fuses, circuit switchers, and circuit breakers. A brief discussion of GIS substations is also offered. The chapter concludes with comments on environmental concerns associated with the operation and retirement of switching equipment, including insulating oils.

Chapter 5, concerned with "High-Voltage Power Electronic Substations," focuses on the specifics of power electronics as applied in substations for power transmission purposes. The first section is devoted to HVDC converter stations and details their components and their operational features. This is followed by discussion of features of FACTS controllers such as static VAR compensators and STATCOMs. The section offers a rich collection of pictures showing existing installations. The control and protection system features for HVDC and FACTS stations are discussed next. Losses and cooling considerations are extremely important and many details are offered concerning their impact on the proper functioning of the system. Civil works considerations are discussed, as well as reliability and availability, before a discussion of future trends is offered.

The interface between automation and the substation is discussed in Chapter 6. In the introduction we learn that the substation automation (SA) system depends on the interface between the substation and its associated equipment to provide and maintain the high level of confidence required for power system operation. It must also serve the needs of other corporate users to a level that justifies its existence. This chapter describes typical functions provided in utility SA systems and some important considerations in the interface between substation equipment and the automation system components. This includes the analog data acquisition function, status monitoring, and control functions. A detailed discussion of communications networks inside the substation is offered. The subject of "testing automation systems" concludes the chapter.

In Chapter 7, "Substation Integration and Automation," we learn that the integration of intelligent electronic devices (IEDs) in the substation presents many challenges to electric utilities. Under the heading "definitions and terminology" it is pointed out that substation integration and automation can be broken down into five levels, or layers. Two of these levels are interface levels: power system equipment (e.g., transformers and breakers) to IEDs, and substation to utility via multiple utility enterprise connections. The three middle levels are IED implementation, IED integration via data concentrator/ substation host processor, and substation automation applications. Definitions of IED, IED integration, and substation automation are offered. Open systems are introduced, and system architecture details are discussed. An evaluation of factors affecting decision-making concerning new and existing substations is offered. Recent developments in equipment condition monitoring are explored, followed by a brief discussion of substation integration and automation technical issues. An introduction to communication protocols and considerations affecting the choice of the appropriate protocol for the application are given.

Containing oil spills at substations is important because of the associated environmental impacts and the required cleanup governed by federal, state, and local jurisdictions. This is the subject treated in Chapter 8, "Oil Containment." The chapter is based on IEEE Standard 980-1994 (R2001). The discussion begins with details of oil-filled equipment that exists in substations; these include transformers, circuit breakers, and cables. Oil handling and storage equipment are discussed, followed by a detailed discussion of spill risk assessment procedures. Containment selection considerations and oil spill prevention techniques are explained and the tradeoffs involved are evaluated.

In Chapter 9 "Community Considerations" are discussed. It is generally acknowledged that community acceptance generally includes the planning, design, and construction phases of a substation. There are significant issues that could influence a community's willingness to accept building a substation at a specific site. These aspects are discussed as part of a discussion of planning strategies and design. The third section deals with a general outline of factors involved in the substation permitting process. The construction phase is described in terms of site preparation, noise control, safety and security, and site housekeeping. Factors involved in the proper operation of a substation are then detailed. Defining terminology based on IEEE Std. 1127-1998 concludes the chapter. The contents of this chapter overlap with those of Chapter 1, but not in a major way.

Chapter 10 treats "Animal Deterrents/Security" by beginning with a list of animal types whose activities can create undesirable consequences for the substation owner, such as conductor bridging, and their typical clearances. Methods for deterring animals are described in detail.

"Substation Grounding" is the subject of Chapter 11. The discussion starts with detailing reasons that make a substation grounding system necessary. In the section "Accidental Ground Circuit" the conditions that can cause a person within or around the substation to become part of the ground circuit are touch voltage and step voltage. Fault current is discharged to Earth by the substation grounding system and a person touching a grounded metallic structure. Permissible (tolerable) values of current and voltage are discussed. The discussion is well supported by analytical expressions and diagrams as well as empirical curves. A section on "Design Criteria" concludes the chapter, where the limits on touch and step voltages are evaluated and the impact of soil resistivity is highlighted.

The basis for the discussion of Chapter 12 covering "Grounding and Lightning" is that substation design involves more than installing equipment. The significant requirement for reliable continuous operation of the facility requires detailed attention to preventing surges (transients) from entering the substation facility. These surges can be switching surges, lightning surges on connected transmission lines, or direct strokes to the substation facility. The chapter focuses on the design process for providing effective shielding (that which permits lightning strokes no greater than those of critical amplitude [less design margin] to reach phase conductors [IEEE Std. 998-1996]) against direct lightning stroke in substations. The discussion turns to lightning parameters including strike distance, stroke current magnitude, Keraunic level (which is defined as the average annual number of thunderstorm days or hours for a given location), and ground flash density (the average number of strokes per unit area per unit time at a particular location). The chapter also discusses the evolution of lightning detection networks, which have been developed to pinpoint the location of lightning strokes. Taking advantage of this technology allows detection of approaching thunderstorms. The discussion of the section on "Empirical Design Methods" focuses on the two classical design methods that were employed to protect substations from direct lightning. Various electro-geometric models (EGM) were developed for designing protection systems as a consequence of the increase in voltage levels. A section in this chapter offers a comprehensive treatment of the subject. Calculating the failure probability for systems designed using available methods are discussed in detail. The section on "Active Lightning Terminals," which improve the performance of lightning protection designs, concludes this well-written chapter.

Chapter 13 deals with "Seismic Considerations" and begins with a historical perspective on the issues involved. We learn that prior to 1970 seismic requirements for substation components were minimal. The large-magnitude earthquakes that took place in the 1970s and 1980s provided the impetus to develop seismic guidelines beginning with IEEE Std. 693-1997. In the section "Relationship between Earthquakes and Substations," the discussion deals with the response of structures and buildings to ground motion. Applicable documents are then discussed to help the designer create the proper construction. Once document familiarization is complete, the designer can follow the steps as outlined in the section on "Decision Process for Seismic Design Considerations" which were created with the assumption that each substation component will be reviewed independently. Determining the appropriate performance level for seismic qualification of the site must be selected in accordance with steps indicated in the section on "Performance Levels and Required Spectra." The section detailing the "Qualification Process" concludes this chapter.

The incidence and risk of fire in substations has been historically low, but the possible impacts of a fire can be catastrophic, and Chapter 14 provides a discussion of "Substation Fire Protection." In the first section, "Fire Hazards," we learn that cables are a major cause of fire because they contain both a fuel as well as an ignition source. Passive, active, and manual fire protection measures are discussed next. Selection of fire protection procedures and equipment is treated in some detail. The chapter offers a "Review Checklist" for fire-protection of a substation control building, This is followed by an appendix dealing with an assessment process for substation switchyard fire protection.

"Substation Communications" is the subject of Chapter 15. A historical perspective on supervisory control and data acquisition (SCADA) is offered after a brief introduction. Functional and communication requirements of SCADA systems are discussed in detail. Components of a SCADA system are then presented. A historical discussion of SCADA communication protocols is offered. The structure of a SCADA communications protocol is detailed and is followed by a discussion of security for substation communications. This latter topic will be covered in more detail in a subsequent chapter. The electromagnetic environment and its requirements are also discussed. Communications media are also covered. In the concluding section, "Additional Information," the authors give an extensive list of additional resources to pursue the topic further.

"Physical Security" is discussed in the new Chapter 16. A historical discussion is offered before a comprehensive listing of the types of intruders is given. Substation development from a security point of view is detailed prior to concluding with a coverage of security methods and security assessment.

Chapter 17 is one of the new additions to this fine collection of chapters and deals with "Cyber Security of Substation Control and Diagnostic Systems." In the "Introduction," the authors inform us that in contemporary times, monitoring, control, and communications with substations rely on wide area networks. These networks are potentially accessible by the general public causing a potential threat to the integrity of the system. Following a listing of definitions and terminology, the threats to the security of substation systems are detailed. This is followed by a discussion of SA system vulnerabilities and measures to enhance cyber security, as well as devising a security policy. The chapter concludes with a discussion of future measures.

Chapter 18 treats the relatively new area of "Gas-Insulated Transmission Line (GIL)," reporting on advances since the introduction of GIL in 1974 to connect the generator of a pumped storage hydro plant to a 400-kV overhead line through a mountain tunnel. The chapter offers details of system design including standard units and laying methods such as direct burial, above ground, and tunnel-laid options. Under the heading "Development and Prototypes" the author discusses gas mixture properties and type tests and their results. A general discussion of the advantages of GIL is concerned with safety and gas handling as well as field effects. Applications of second-generation GIL are discussed before an outline of aspects of quality control and diagnostic tools are highlighted. Corrosion protection and voltage stress caused by the electric power network are also treated. A section on the future needs of high-power interconnections concludes the chapter.

John McDonald states in his preface "the objective of Electric Power Substations Engineering is to provide an extensive overview of the substation, as well as a reference and guide for its study." This reviewer believes that this objective has been attained and the book is a welcome addition to the electric power engineering literature. The emphasis of the book is on the practical application of technology, and it is written in an easy-to-read, tutorial style with many photographs and graphics. Each of its 18 chapters is authored by leading members of the IEEE PES Substations Committee and includes many references to industry standards. The book would be a valuable supplement to the academic text for many undergraduate and graduate power engineering courses.

reviewed by M.E. El-Hawary

Editor's Note: Tutorials to be offered at the 2004 General Meeting in Denver (6–10 June) are based on information contained in this book. Details of the presentations are posted on the PES Web site and in the E-Newsletter.