Harmonic Active Filter Using Multiplication Sine Function Method to Reduce Current Distortion

The use of Variable Frequency Drives (VFDs) is unavoidable, especially in the industrial sector, where motor speed regulation is required to expedite production. VFDs are included in nonlinear loads, which, when in use, can cause the voltage and current of the source to differ. When a source carries a nonlinear load, the current distorts, resulting in a non-sinusoidal shape. The degree of distortion, Total Harmonic Distortion (THD), shows that as THD increases, the signal becomes more distorted. To reduce the distorted source currents, active harmonic filters are used and arranged in parallel between the source and the load. The active harmonic filter works by producing a harmonic current that eliminates the distorted source current, which is achieved by extracting the current distortion signal using the multiplication-with-sine-function method. When the mesh source is loaded with a VFD, the THD of the source current is 45.35%. According to the 2014 IEEE-519 standard, the maximum THD value of the current should be 5%, which is not met, so an active harmonic filter is installed. After installing the active harmonic filter, the THD of the current dropped to 3.57%. This was achieved with a VDC setpoint of 500 V, stabilized by Proportional Integral (PI) control with a P value of 17.543 and I value of 0.00018.