Optimization

In the first edition this chapter was titled Prioritization Methods for O&M and discussed methods for reliability centered maintenance (RCM) of a utility delivery system. The new title reflects a slightly expanded scope. RCM is still covered as before. But the basic prioritization approaches applied in the RCM examples can be set up to work toward maximizing something other than reliability, such as increased lifetime or business value – related but slightly different goals. This chapter discusses the concepts that apply to trying to optimize any goal with respect to service, maintenance, refurbishment, and life extension of power delivery equipment, using RCM as its main example. The goal of virtually every organization is to try to maximize the results it wants and minimize the consequences it does not. Often this is referred to as optimization. That word, along with its verb, adverb and adjective versions, are often horribly abused terms. Few optimization methods, at least as practically applied, truly find an optimal answer or plan. They find good or pretty good solutions instead, often better ones than a project team can find unaided by such tools. Often other products of optimization’s use are as valuable as the “optimum answer” it provides, products such as the determination of the true cost of constraints and limitations that must be respected, or the interaction effects of various conflicting business goals, etc. This chapter focuses on methods utilities and industrial power system owners can use to decide how to maximize the care of the power systems they own. Here, “care” means the expenditure of O&M budgets and resources – non-capital resources – on the system, in order to assure that equipment can and will continue

to be able to do its job dependably and safely. Regulated utilities are permitted to pass legitimate and approved amounts of O&M expenses on to their customers via the rates they charge for power and energy. However, those O&M budgets are limited to what has been approved by regulators. Beyond that, many utilities and industrial power system owners have only limited numbers of skilled employees and contractors available to do such work, and only limited windows of time during the year when they can do it. For all these reason, a practical reality of power system ownership is that there are always more apparently worthwhile O&M activities that could be done than can be done. Allocation of O&M boils down to priorities – to favoring certain activities like inspection and tracking over more service, or focusing on equipment of a certain age and equipment rather than all equipment, or on only certain types of equipment and not all. This chapter discusses both the function of deciding on how much to fund on what equipment care activities, and why, and analytical and procedural methods used by power system owners to do so. Entire books can and have been written about power system equipment maintenance and service, and provide great detail on techniques as well as the ifs, ands, and buts of maintenance and service applied to different equipment and situations (See References and Bibliography). This chapter focuses on breadth rather than depth, providing an overview with a focus on how the function and the techniques available work toward managing an aging power delivery infrastructure. Section 12.2 begins with some basic concepts about maintenance and service focus and the use of optimization. Sections 12.3 and 12.4 then examine a large (for a textbook) RCM example in a series of evolutions from simplistic to fairly detailed evaluation. Sections 12.5 and 12.6 review several practical issues required to fit technical methodology to a power system’s business needs. Section 12.7 then takes up the concept of optimization, a decision-making process that addresses more than one goal (e.g., reliability and extended equipment lifetime) and considers practical constraints (Project A has to be done before Project B can be done, only one of Projects C, D, or E can be done). The chapter concludes with a summary of key recommendations in Section 12.8.