Optimal expansion planning of distribution substations for taipower distribution system

This paper is to investigate the optimal substation capacity expansion problem for distribution system. The monthly energy consumption and the service types of all customers within each fence area have been retrieved from the customer information system in Taipower. The load demand of each fence area is calculated according to the typical load patterns and energy consumption of customers. The S curve with different time constant is used to represent the load growth of each customer class for the load forecasting of each fence area. The load flow analysis is performed to find power demand of each fence area for annual system operation over the study period. The objective function is formulated by considering both the cost of power loading loss and investment cost of substations as the equivalent cost of all feasible states of each year. By performing the dynamic programming (DP) to minimize the objection function, the expansion planning of substations to achieve the minimum overall cost has been obtained by identifying the locations and the years for the new substations to be committed at each year.