Active Power Filter Solution without PLL for Fluctuating Industrial Load

To improve the quality of electrical power to the consumers, many power electronic based solutions are available. In the case of active power factor compensation, grid tied voltage source inverter based STATCOM is one of the versatile solution. But in this system most of the control strategies demand generation of unit vector, based on the grid voltage for vector orientation. But presence of harmonics in grid voltages and the level of noise in the grid voltage sensing circuits will make estimation of unit vector difficult and PLL circuits will become a necessity. This paper presents a simple and efficient method to evaluate the unit vector without the use of PLL or any hardware filter. This method uses d-q reference frame control strategy for shunt active filter and has been tested with a 100 kVAR system. The experimental results are presented to validate the effectiveness of this control strategy.