In this study, a new control theory has been proposed to regulate DC bus voltage of shunt active power filters used to solve the power quality problems caused by nonlinear loads in power systems. DC bus voltage of the filter must be controlled to supply the power losses of filter from the grid, providing that more effective filtering and reactive power compensation are obtained. The DC bus capacitor voltage of filter to measure voltage sensor in the algorithm developed has not been used unlike previous studies. Instead of this, DC bus voltage has been regulated by considering difference between reference compensation current and real compensation current of the filter at fundamental frequency. Experimental and simulation studies performed have indicated the simple structure, effectiveness of the proposed control theory and the low cost unlike others studies.