Power System SCADA and Smart Grids

Mini S. Thomas, John Douglas McDonald

• Editore: CRC Press
• Anno: 2017
• ISBN:
  9781351831260
• Edizione: 1
• Argomento: Physical Sciences
• Categoria: Energy

Power System SCADA and Smart Grids brings together in one concise volume the fundamentals and possible application functions of power system supervisory control and data acquisition (SCADA). The text begins by providing an overview of SCADA systems, evolution, and use in power systems and the data acquisition process. It then describes the components of SCADA systems, from the legacy remote terminal units (RTUs) to the latest intelligent electronic devices (IEDs), data concentrators, and master stations, as well as:

• Examines the building and practical implementation of different SCADA systems
• Offers a comprehensive discussion of the data communication, protocols, and media usage
• Covers substation automation (SA), which forms the basis for transmission, distribution, and customer automation
• Addresses distribution automation and distribution management systems (DA/DMS) and energy management systems (EMS) for transmission control centers
• Discusses smart distribution, smart transmission, and smart grid solutions such as smart homes with home energy management systems (HEMs), plugged hybrid electric vehicles, and more

Power System SCADA and Smart Grids is designed to assist electrical engineering students, researchers, and practitioners alike in acquiring a solid understanding of SCADA systems and application functions in generation, transmission, and distribution systems, which are evolving day by day, to help them adapt to new challenges effortlessly. The book reveals the inner secrets of SCADA systems, unveils the potential of the smart grid, and inspires more minds to get involved in the development process.

chapter one

Power system automation

1.1 Introduction

The global electricity demand is growing at a rapid pace, making the requirements for more reliable, environment friendly, and efficient transmission and distribution systems inevitable. The traditional grids and substations are no longer acceptable for sustainable development and environment-friendly power delivery. Hence, the utilities are moving toward the next-generation grid incorporating the innovations in diverse fields of technology, thereby enabling the end users to have more flexible choices and also empowering the utilities to reduce peak demand and carbon dioxide emissions to become more efficient in all respects.

Power engineering today is an amalgam of the latest techniques in signal processing, wide area networks, data communication, and advanced computer applications. The advances in instrumentation, intelligent electronic devices (IEDs), Ethernet-based communication media coupled with the availability of less-expensive automation products and standardization of communication protocols led to the widespread automation of power systems, especially in the transmission and distribution sector.

In today’s world with limited resources and increasing energy needs, optimization of the available resources is absolutely essential. Conventional power generation resources such as coal, water, and nuclear fuels are either depleting or raising environmental concerns. Renewable sources are also to be utilized judiciously. Hence there is a need to optimize the energy use and reduce waste. Automation of power systems is a solution toward this goal, and every sector of the power system, from generation, to transmission to distribution to the customer is being automated today to achieve optimal use of energy and resources.

In order to integrate the new technologies with the existing system, it is necessary that the practicing engineers are well versed with the old and new technologies. However, in the present scenario, most of the engineering professionals learn the new technology “on the job” as the pace of technology development is very fast with the advent of new communication protocols, relay IEDs, and related functions. This is all the more relevant in the core field of power engineering as the power industry needs trained engineers to keep up the pace of the rapid expansion the power industry is envisaging, to meet the energy consumption that is expected to triple by 2050. It is pertinent to explore the automation of power systems in detail.

1.2 Evolution of automation systems

The evolution of automation systems could be traced back to the first industrial revolution (1750–1850), when the work done by the human muscle was replaced by the power of machines. During the second industrial revolution (1850–1920), process control was introduced and the routine functions of the human mind and continuous presence were taken over by machines. The human mind was relieved of the bulk and tedious physical and mental activities. Michael Faraday invented the electric motor in 1821, and James Clark Maxwell linked electricity and magnetism in 1861–1862. In the later part of the nineteenth century, there were rapid developments in electricity and supply of electric power with the giants like Siemens, Westinghouse, Nikola Tesla, Alexander Graham Bell, Lord Kelvin, and many others contributing immensely. In 1891, the first long-distance three-phase transmission line of high power was featured at the International Electro-Technical Exhibition in Frankfurt. Along with the developments in electric power generation, transmission, and distribution to customers, the automation including remote monitoring and control of electric systems became inevitable.

The initial control equipment consisted of analog devices which were large and bulky, and the control rooms had huge panels with innumerable wires running from the field to the control center. The operator could not make use of the information available, as during an emergency, a number of events occurred simultaneously and it was impossible to handle all of them since there was no intelligent alarm processing. Excessive cost was associated with a reconfiguration or expansion of the system. The expensive space requirement was also a constraint in the case of analog control, as the control panels were large. Storage of information was also an issue, as for power systems post-event analysis is crucial.

With the introduction of computers into the automation scenario, automation became more operator friendly, although initially computer use was restricted to data storage and to change set points for analog controllers. Early digital computers had serious disadvantages such as minimal memory, poor reliability, and programming written in machine language.

Two major developments led to the advent of distributed control: the advances in integrated circuits and in communication systems. Distributed control systems were modular in structure, with preprogrammed menus, having a wide selection of control algorithms for execution. The data highway became possible with the introduction of new communication techniques and media. Redundancy at any level was possible, due to the availability of components at cheaper rates, and extensive diagnostic tools became part of the supervisory control and data acquisition (SCADA) systems.

1.2.1 History of automation systems

Supervisory control and data acquisition (SCADA) systems are widely used for automation of the power sector and represent an evolving field, with new products and services added on a daily basis. Detailed study of SCADA systems is essential for power automation personnel to understand the integration of devices, to understand the communication between components, and for proper monitoring and control of the system in general.

There were undoubtedly many methods of remote control invented by early pioneers in the supervisory control field which have long since been forgotten. Control probably began with an operator reading a measurement and taking some mechanical control action as a result of that measurement.

Most early patents on supervisory control were issued between 1890 and 1930. These patents were granted mainly to engineers working for telephone and other communication industries. Almost all patents involving remote control closely followed the techniques of the first automatic telephone exchange installed in 1892 by Automatic Electric Company.

From 1900 until the early 1920s many varieties of remote control systems were developed. Most of these, however, were of only one class or the other (i.e., either remote control or remote supervision [monitoring only]). One of the earliest forerunners of the modern SCADA system was a system designed in 1921 by John B. Harlow. Harlow’s system automatically detected a change of status at a remote station and reported this change to a control center. In 1923, John J. Bellamy and Rodney G. Richardson developed a remote control system employing an equivalent of our modern “check-before-operate” technique to ensure the validity of a selected control point before the actual control was initiated. The operator could also ask for a point “check” to verify its status.

The first logging system was designed by Harry E. Hersey in 1927. This system monitored information from a remote location and printed any change in the status of the equipment together with the reported time and date when the change took place.

As the scope of supervisory control applications changed, so did many of the fundamentals of supervisory control technology. During the early years all of the systems were electromechanical. The supervisory systems evolved to using solid-state components, electronic sensors, and analog-to-digital convertors. In this evolution, however, the same remote terminal unit (RTU) configuration was maintained. The companies making the RTUs merely upgraded their technology without looking at alternate ways of performing the RTU functions. In the 1980s process control companies began applying their technology and technical approach to the SCADA electric utility market. As a result, RTUs used microprocessor-based logic to perform expanded functions. The application of microprocessors increased the flexibility of supervisory systems and created new possibilities in both operation and capabilities.

1.3 Supervisory control and data acquisition (SCADA) systems

Automation is used worldwide in a variety of applications ranging from the gas and petroleum industry, power system automation, building automation, to small manufacturing unit automation. The terminology SCADA is generally used when the process to be controlled is spread over a wide geographic area, like power systems. SCADA systems, though used extensively by many industries, are undergoing drastic changes. The addition of new technologies and devices poses a serious challenge to educators, researchers, and practicing engineers to catch up with the latest developments.

SCADA systems are defined as a collection of equipment that will provide an operator at a remote location with sufficient information to determine the status of particular equipment or a process and cause actions to take place regarding that equipment or process without being physically present.

SCADA implementation thus involves two major activities: data acquisition (monitoring) of a process or equipment and the supervisory control of the process, thus leading to complete automation. The complete automation of a process can be achieved by automating the monitoring and the control actions.

Automating the monitoring part translates into an operator in a control room, being able to “see” the remote process on the operator console, complete with all the information required displayed and updated at the appropriate time intervals. This will involve the following steps:

• Collect the data from the field.
• Convert the data into transmittable form.
• B...