LAUSR

In this work, a voltage regulation scheme to stabilize voltage variation in the consumer side is proposed. The voltage regulation scheme uses IGBT-based onload tap changer (OLTC) and nonlinear hysteresis control algorithm. The proposed switching algorithm establishes the commutation of the taps without redundant short circuit operation of the taps. The experimental results of the designed system show accurate voltage regulation at the consumer side and high ability of the designed system to fix voltage sag and voltage swell in maximum of one cycle period. The paper considers the consequences of fault in the drive circuit of the IGBT tap changer and discusses its reliability. The analysis and the experimental results of the faults in the drive circuit show that the loss of one drive signal results in a large circulating DC current in the primary circuit and may result in fault current of value more than three times the operated current, which leads to unavailability of the system.