Structural Analysis and Efficiency Trend of Electricity Distribution Companies in Iran by Using Window Data Envelopment Analysis

The analysis of efficiency trend by applying window Data Envelopment Analysis and research about environmental and structural forces affecting on efficiency in electricity distribution companies after vertical decomposition and ownership change in Iran is very important object. On the basis of circuit density, companies decomposed in two groups with low circuit density (group1) and high circuit density (group2). On the basis of research results, window efficiency mean of first and second groups under the variable and constant returns to scale with respect to metafrontier have had increasing and decreasing trend respectively. But second group efficiency mean is higher than first group efficiency mean into whole windows. Shiraz city, Golestan and Mazandaran electricity distribution companies in second group have had unsatisfactory performance with respect to metafrontier and group frontier in comparison to other companies. High circuit density companies have had fewer gaps between group performance and potential better performance or metafrontier. Network load factor increasing would be led to lower efficiency and transformator load factor increasing would be led to higher efficiency. Privatization has insignificant effect on efficiency in the short-run but has significant effect in the long-run.