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For the power flow control and effective utilization of the installed transmission and generation systems,a power flow controller "Direct power flow controller based on synthesis of two 600 phase different voltages"(DPFC-S60)is proposed.In comparison with SSSC,UPFC and STATCOM,DPFC-S60 is not utilizing any dc energy storage element therefore it avoids all the disadvantages brought by dc energy storage elements i.e.it will possibly reduce the maintenance cost,and will have low failure rate and extended life compared to the devices containing dc energy storage elements.The proposed controller has the ability to regulate the phase angle and amplitude of its output compensating voltage.The compensating voltage upon addition with the original grid voltage regulate the active and reactive power flow.DPFC-S60 is a kind of direct power flow controller(DPFC)whose compensating voltages are obtained from the synthesis of two voltages which have a phase difference of 600 between them.DPFC-S60 has no 3rd harmonic currents and voltages.DPFC-S60 has a single stage conversion circuit and is composed of an output transformer,two input transformers,six buck type ac units,two selection switches and three single phase output filters.In comparison with its input voltage the basic DPFC-S60 can regulate the phase angle of its output voltage up to 600.The 600 regulation range is extended to 3600 by employing two selection switches.The operation principle,and th circuit design is studied in detail.The regulation of grid voltage with the introduction of the compensating voltage to the grid and the variation of the compensating voltage’s phase angle and amplitude with varying duty ratios in different regulatory zones is researched in detail.An approach for the regulation of grid voltages in unbalance case has been presented.Simulations were performed using Saber simulation software to verify the theory of DPFC-S60.Simulation results for both balanced and unbalanced cases are discussed.A prototype was designed for DPFC-S60 with DSP TMS320F2812 as the core controller.DPFC-S60’s hardware and software designs are discussed.Experiments were performed using the designed prototype Experimental results confirmed its feasibility and justified the theoretical reasoning of the proposed DPFC-S60.