This paper introduces an advanced control strategy on battery energy storage systems (BESS) for bidirectional power control and stability improvement. The proposed control strategy efficiently controls the charging-discharging states of BESS as well as provides bidirectional control on both active and reactive powers. The introduced control scheme is equipped with supplementary stabilizers to damp out the oscillations and stability improvement. The problem of designing the controllers is mathematically expressed as a constrained optimization programming and solved by particle swarm optimization (PSO). The results show that the proposed control strategy can efficiently control both active and reactive powers independent of each other. As well, it is able to change the direction of both active and reactive powers from positive to negative and vice-versa. The designed stabilizers also improve stability of the network and damp out the oscillations following large-signal and small-signal disturbances. (C) 2017 Elsevier Ltd. All rights reserved.