Energy efficiency improvement of a single-phase AC spot welding machine by using an advanced thyristor switched detuning capacitor bank

This paper presents the improvement of power quality and operational energy efficiency by using an advanced thyristor switched detuning capacitor bank (TSC). The operation of an ac spot welding load invokes serious power quality problems, such voltage fluctuation, poor power factor, and harmonic distortion, resulting in additional power dissipations of the transformer, and also reducing the operational energy efficiency of the load. Hence, this paper proposes a fast reactive power compensating solution to improve the overall power quality of the distribution power system. The selection of compensation capacity and its improvement result are presented and discussed. Furthermore, this study evaluates the specific improving result through various losses and indicators, including power dissipation, harmonic loss factor, maximum permissible load current, and top-oil temperature rise of the transformer. From the calculated curves, the improvement results with different TSC capacity can be observed. Finally, from the implement and the experimental result, the proposed solution can effectively improve the operational energy efficiency as well as the power quality of the power system.