A general decentralized voltage control scheme is proposed to coordinate the operation of DG, Voltage regulator and Capacitor banks. The present invention is based on placing a Remote Terminal Unit (RTUs) at each distribution generation (DG) and each at line capacitor. These RTUs being coordinated together through communication protocols form a multi-agent system. Novel decentralized system is proposed to estimate the voltage profile change as a result of injecting reactive power at the capacitor bus. Simulation results are presented to show the validity and the effectiveness of the present invention.