Loss Evaluation; Part I. Losses Associated with Sale Power - In-Phase Method [includes discussion]

Losses associated with sale power are determined from a family of charts, constructed as described in the paper. The losses are given as a function of total system load, power over the interconnections, and amount of sale power from each generating station. The simplifying approximations used are: 1. Reduction of the transmission system to a simplified equivalent without internal loops. 2. Current equal to power in per cent of base. 3. Fixed distribution through the tie lines of sale power from a given generating station. 4. Fixed dispatch of system load. These approximations may be modified. The method has been in use by Commonwealth Associates, Inc., for a number of years and is applicable to systems where these approximations are valid. The advantages of the in-phase method are: 1. The simplicity and directness with which incremental losses associated with sale power can be determined. 2. The flexibility in determining losses for a wide variety of system load and sale conditions. 3. No computer is required either in the preparation or use of the charts. This paper describes one phase of a joint study of loss evaluation conducted by Commonwealth Associates, Inc., the Consumers Power Company, and the Westinghouse Electric Corporation. Current- and powerform loss formulas are described in a companion paper.1