Application of Single-Phase Supply AC-DC-AC VFD for Power Factor Improvement in LED Lighting Devices Loaded Power Distribution Lines

Abstract

More and more light-emitting diode lighting devices (LED) are being connected to modern power distribution lines. In addition to its many positive features, this poses problems in terms of reactive power compensation. The large number of LEDs interacting with traditional reactive power compensators leads to a harmful phenomenon—overcompensation. This was experimentally determined in the investigated power distribution lines. Along with LEDs, a large number of devices with variable frequency drives (VFD) are connected to the same power distribution lines. This study presents an innovative approach to conventional diode rectifier supply side AC-DC-AC VFDs. It is proposed to use these VFDs as a reactive power compensation device while maintaining their main functions—motor powering and motor speed control. Minor improvements have been proposed to enable these VFDs to provide and draw out reactive power, thereby keeping power factors close to the unit in LED-loaded power distribution lines. The proposed improvements are based on the interaction between the power distribution lines inductivity and the DC circuit capacitance of the VFD. It has been shown that the power factor can be controlled by varying the capacity of the DC circuit. The ability of the AC-DC-AC VFD to compensate for the reactive power provided by the light-emitting diode lighting devices was confirmed by mathematical calculations and experimentally with a laboratory prototype.