This paper presents an efficient fast decoupled power flow control method e.g. method for automatic adjustment of a phase shifting transformers (PST) for specific line flows. The effects of a PST are represented by injection model and the corresponding extension of conventional load flow equations is made. Furthermore, the load flow control by means of PST is modeled by additional equations. For solution of the power flow control problem defined the special fast decoupled procedure is developed. The high numerical efficiency and simplicity of this procedure has been established on the example of real interconnection formed by the power system of Serbia and Montenegro, Romania, Bulgaria, Former Yugoslav Republic of Macedonia, Greece and Albania (Second UCTE synchronous zone).