Wireless Sensor Networks consist of spatially distributed and energy-constrained autonomous devices called sensors to cooperatively monitor physical or environmental conditions such as temperature, sound, vibration, pressure or pollutants at different locations. Because these sensor nodes have limited energy supply, energy efficiency is a critical design issue in wireless sensor networks. Having all the nodes simultaneously work in the active mode, results in an excessive energy consumption and packet collisions because of high node density in the network. In order to minimize energy consumption and extend network life-time, this thesis presents a centralized graph partitioning approach to organize the sensor nodes into a number of active sensor node sets such that each active set maintains the desired level of sensing coverage and forms a connected network to perform sensing and communication tasks successfully. We evaluate our proposed scheme via simulations under different network topologies and parameters in terms of network lifetime and run-time efficiency and observe approximately 50% improvement in the number of obtained active node sets when compared with different active node set selection mechanisms.