Abstract: The analysis on the macro statistic data of the power industry of a country or a region can reveal the historical development of power grids utilization and the relationship between the utilization level and the electric demand growth of the whole society. This article proposes a set of indicators of the power grids utilization level and the estimation approaches on these indicators, as well as a set of development elastic coefficients which demonstrate the relationship between the growth rates of power grids and electric demands. To verify the applicability of these indicators, the article also analyses the historical data of the power industry of Japan between 1963 and 2011 through plotting the historical curves, and studies the development of the power grids in Japan from the aspect of grids utilization. The results show that the power grids in Japan developed ahead of the economy in a specific period, and the utilization level is quite different between the power grids of different voltages, and the power grids utilization levels are strongly affected by the economic development and fluctuations.

Key words: transmission line utilization rate, substation equipment utilization rate, power development elastic coefficient, Japan power industry