Operations Research Determination of Generation Reserves

This paper presents the results of a study concerned with: 1. The determination of the most economic time to add new turbogenerator units to an electrical utility system or, equivalently, the determination of an optimum reserve generating capacity policy. 2. The determination of the most economic sizes of units to be added to the system. As this paper shows, these two problems are interrelated and methods for their solution are developed and presented. Reserve generating requirements vary for each individual power system, and are affected by: 1. The number and sizes of the generating units within the system. 2. The probability of a forced outage for units within the system. 3. The additional available power that can be obtained from other sources such as interconnections. 4. Scheduled or preventive maintenance requirements. 5. Customer demand for power. 6. The maximum risk of shortage to be tolerated. In the past, most of the power utility companies in the United States had approximately the same distribution of sizes of generating units within each system, and the same risk of shortage was accepted by each company. Consequently, it was possible to use a rule of thumb to calculate the total reserve requirements that should be carried by each company. However, with the introduction of the large, high-pressure generating units that are being installed today, it is no longer possible to use a constant percentage in determining the reserve requirements.