Abstract
This paper proposes a new methodology for planning of power supply program.
Firstly we suggest that the power supply program should be planned not monthly but weekly and be evaluated by the loss of load probability (LOLP), which assesses the degree of balance of power demand and supply at the time of weekly peak load, for each week about 52 weeks a year. Because we don't think that the monthly power supply program is adequate since the daily or weekly peak load changes remark-ably in such transient season as the period from spring to summer or from summer to fall. In case of large power system the calculation method by the convolution for assessing LOLP is not practical due to the complicated calculation procedure and the long calculation time.
So we secondarily propose to use the Gram-Charlier series expansion for a probability distribution function to calculate the LOLP. This series has a high degree of approximation for a number of units and very short calculation time.
