Voltage Quality Improvement Using AC-Chopper in Distribution Line

Voltage sag is an important power quality problem, which may affect domestic, industrial and commercial customers. Voltage sags may either decrease or increase in the magnitude of system voltage due to faults or change in loads. Momentary and sustained over voltage and under voltage ma y cause the equipment to trip out, which is highly undesirable in certain application. In order to maintain the load voltage constant in case of any fluctuation of input voltage or variation of load some regulating device is necessary. The focus of this paper is the study of direct alternating-current (ac)–ac converters. The ac/ac power converter takes energy from the grid during voltage sag/swell. By connecting the ac-chopper converter’s input terminals on the load side and injecting the compensation voltages on the supply-side, it is possible to hold a constant input voltage, resulting in an efficient solution for compensating deep voltage sags and swells. Thus, this paper proposed to eliminate the sag and swells. It has the ability to compensate balanced and unbalanced voltage fluctuations and to eliminate the energy storage elements. The pulse width modulation (PWM) technique is utilized to fulfil the input and output requirements. Numerical simulation results are presented to validate the approach. Voltage compensator based on an AC buck chopper, which is operated using the strategy of non-complementary control without current detection. It is suitable for compensation long term voltage sags and could adjust pulse widths according to the ratio of required output in real time. Simulations and experiment results proved functionality of this circuit.