Independent Fast Phase Shifting Transformer: A Flexible and High-Precision Power Flow Controller

With the increasing proportion of renewable energy sources in modern power systems, the power flow problem has become more prominent. The traditional phase shift transformer (PST) has the advantages of simple structure, high reliability, and low cost. However, PST can only regulate the active power flow of the line by controlling the phase shift angle, and cannot independently regulate the voltage amplitude of the line. In addition, its slow response speed and low regulation accuracy cannot meet the requirements of the new power system for power flow control. Therefore, a novel type of independent fast phase shifting transformer (IF-PST) is proposed. IF-PST has two independent regulating windings. One is on the power side and the other is on the load side. IF-PST can independently regulate the line voltage and active power with higher regulation accuracy than PST. In addition, IF-PST uses power electronic on-load tap changer for tap switching, improving response speed. Firstly, the working principle of IF-PST is introduced, and the independent regulation characteristics are elaborated. Then, the IF-PST winding turns and parameter design method are studied. Correspondingly, a tap selection method and control strategy are developed for IF-PST. On the basis of theoretical analysis, simulation and experimental testing are conducted, and the simulation and experimental results verified the rationality and practicality of IF-PST.