DC link voltage regulation in active filter using drainage power from distribution transformer

Non-linear loads constitute a major part of loads in the modern industrial and commercial utilities. They inject harmonics to the system and the normal delta-star distribution transformer traps the injected triple-n harmonics in the primary delta winding. This leads to the deterioration and reduction in the life of transformer. Hence, a three winding star-star-delta_utilized transformer is used to trap this harmonic or drainage power in the non-linear power system. This drainage power can be used to power auxiliary loads connected across the tertiary delta winding. Also, drainage power recovery makes the system performance better as triple-n harmonics are eliminated from supply line. For balanced and unbalanced secondary non-linear loads, the tertiary power can be recovered. Also, it can be stored in rechargeable batteries to power regulated loads. In this paper, the use of battery stored drainage power for the voltage regulation in shunt active filters is being discussed. The shunt active filter using Icosϕ algorithm provides better harmonic elimination of non-linear load. When a load fluctuation occurs, the dc link capacitor voltage in the filter also fluctuates. Usually, the power needed for voltage regulation is supplied by the grid. In the proposed system, the drainage power stored in the battery is used for the voltage regulation. For using shunt active filter in the YYD_utilized transformer system, the control algorithm of the filter needs to be modified in order to sustain the triple-n harmonics in the system. The power recovered from triple-n harmonics can be stored in a battery and can be further used as the energy storage element of the filter. Results analyzed using MATLAB/SIMULINK reveals that the YYD_utilized system along with shunt active filter gives better utilization of drainage power and the overall system provides harmonic elimination.