This paper presents a model for seasonal reconfiguration of actual distribution network, which is connected to different points of transmission system via subtransmission transforms, taking into account the feature of competitive environments. The objective function is minimizing the cost of purchased energy regarding hourly Locational Marginal Prices (LMPs) of wholesale market, derived from different connection points between distribution and transmission systems, as well as bilateral contracts with Distributed Generators (DGs). The daily load curves of different load categories, i.e. residential, commercial, administrative and teaching centers are considered. Setting the tapchangers of sub-transmission transformers are accomplished along with reconfiguration process considering the 24-h load curves. DG units are assumed to be controlled in PQ mode and the best value for power factor of each DG is determined during reconfiguration. The presented model is solved by Genetic Algorithm (GA), and a straightforward sub-algorithm which is applicable for actual networks is propounded for checking the presence of loop and islanding in the network, thereby the whole feasible solution space is searched. The developed model is evaluated by executing on 16-bus and 204-bus test systems. Different cases are considered and the results are discussed