CHAPTER 6. POWER SYSTEM OPERATION.
6.1 POWER SYSTEM STRUCTURE. This chapter will discuss the structure, the procedures,
and the various switchboards generally applicable to Power System Operating Centers.
6.1.1 Bulk Power System. A bulk power system consists of the generating sources, the
transmission system, and the distribution system. A broad description of each subsystem is
provided in the following subparagraphs.
220.127.116.11 Generating Sources. Generating sources consist mostly of synchronous generators
driven by steam, gas, or hydro turbines. Energy is delivered to the transmission system through a
18.104.22.168 Transmission System. The transmission system consists of separate successive
networks servicing the same geographical area. These networks operate at different voltages and
are tied together at substations. The transmission network also serves to integrate neighboring
power systems with the underlying system through interconnections.
22.214.171.124 Distribution System. The distribution system is similar in structure to the
transmission system, however, each network covers a much smaller geographical area. The
distribution system also provides service to individual customers, rather than providing service to
6.1.2 Power System Objectives. All power systems (utility, industrial, commercial, and
residential) have in common the function of providing electric energy safely, reliably, and as
economically as possible. Correct voltage and frequency wave shape must be continuously
maintained within permissible limits. A complex, but coordinated, control network is required
to provide proper system operation.
6.1.3 Power Systems Control Network. The combination of multiple generating sources and
several layers of transmission and distribution networks provide a high degree of system
redundancy. Superimposed on this physical structure is a control and automation system that is
highly distributed and is designed to provide redundancy in a manner similar to that provided by
the power system.
126.96.36.199 Control Centers. The hierarchy of control centers in the United States, in
descending order from the national level to the local distribution areas, is as follows:
(a) The National Council coordinates regional centers.
(b) The Regional Coordination Center coordinates power pools.