Determination of Reserve-Generating Capability

The following is a summary of the main problems to which the methods discussed have been applied and of points of special interest in connection with these problems: 1. Determination of the magnitude of required reserve in the planning of system additions to meet future load requirements. The two main procedures are the use of probability methods for the determination of forced outages and the use of the constantrisk principle in scheduling overhauling to give the minimum required reserve for a desired degree of reliability. Factors considered include the following: monthly peaking factor, and help from emergency loading of equipment, from interconnections, and from dropping of interruptible load. 2. Evaluation of the savings in owned capability derived from an interconnection and determination of the required capability of the interconnection. These studies presuppose reciprocity over the interconnections on an equal basis. The saving in owned capacity by a given utility is greater than the power interchange by an amount equal to the incremental reserve which would be required if the power were obtained from additions to owned generating equipment. 3. Study of the effect of size of units upon the required reserve in the planning of system additions. The first new unit of a much larger size than existing ones adds to the usable capacity to supply load a much smaller fraction of its capability than that obtained if the added unit is equal in size to the largest existing one.