Take SBW series regulator as an example: SBW consists of three-phase compensation transformer, three-phase voltage regulating transformer, electrical detection unit, servo motor control and transmission mechanism, contactor operation circuit, protection circuit, etc.

    The primary winding of the voltage regulating transformer is connected to the output of the regulator in Y shape, the secondary winding is connected to the primary winding of the compensation transformer, and the secondary winding of the compensation transformer is connected in series in the main circuit. In this paper, the working principle of the voltage stabilization is illustrated by taking one of the phases as an example, as shown in Fig. 1.

    Voltage compensation circuit consists of contact voltage regulator T2 and compensation transformer T1. The contact voltage regulator is connected to the output of the regulator at one time, and the primary coil of the compensation transformer is connected to the primary coil of the compensation transformer. The compensation principle of the secondary coil of the compensation transformer is as follows (2). The impedance voltage drop of the compensation transformer is not calculated: U2 = U1 + Uc.

    Type: U1-Voltage Regulator Input Phase Voltage

    U2-Voltage Regulator Output Phase Voltage

    Uc-Voltage Regulator Phase Compensation Voltage

    When the input phase voltage U1 is changed to U1, the compensation voltage Uc is changed to Uc, and U1= Uc, the output phase voltage U2 will remain unchanged. The adjustment of compensation voltage Uc is based on the change of output voltage. The signal of voltage detection unit is given to control the servo motor to rotate. The brush slides on the contact voltage regulator by deceleration and transmission mechanism. The secondary voltage of the contact voltage regulator is adjusted to change the compensation voltage, so that the output voltage can be stabilized automatically.