ABSTRACT
This chapter looks at the impact that “making do” with limited numbers and sizes of substation sites and sub-transmission rights of way has on the reliability and operation of a power delivery system. As discussed in Chapter 1’s introduction to aging T&D infrastructures, the second of the four interacting aspects of the aging infrastructure issue is the limited facilities which power distribution utilities invariably have in the core of thriving metropolitan areas. Difficulties in getting new sites, in expanding old sites, and in getting rights of way often mean that the utility’s system can not expand in company with the demand of an ever-growing downtown area. This chapter looks at this problem and the effects that it has on power system performance. Section 8.2 presents the basic problem with some examples. Section 8.3 then examines the impacts that “outdated” or limited system structures have on the engineering decisions that planners must make with regard to the sub-transmission and substation levels of the system, and on the operating characteristics and daily constraints faced by the people managing that part of the system. All of these effects compromise the system’s reliability. Section 8.4 looks at similar impacts on the primary feeder system, which degrade its potential to contribute economy of operation and reliability to the system. Section 8.5 summarizes the various solutions and improvements recommended for the distribution utility faced with this problem. Key points are summarized in Section 8.6.
