At present, with the development of social economy, a large number of nonlinear loads have been introduced into the power grid, which has also brought a series of power quality problems to the power grid such as voltage fluctuations, low grid-side power factor, three-phase voltage imbalance and high harmonic content. Therefore, Static Var Generators (SVG) have been successively launched at home and abroad to tackle power quality problems. As an important component of the SVG system, the special connection transformer matched with SVG features a high impedance, which enhances the transformer's short-circuit resistance. In addition, the transformer adopts a new type of process treatment method, endowing it with unique harmonic characteristics: the total harmonic distortion (THD) of the secondary winding current is not more than 10%, among which the 2nd harmonic is not more than 4%, the 3rd and 4th harmonics are not more than 2%, and all other harmonics are not more than 1%.