Reactive Power Compensation for Single-Phase AC Motors Using Integral Power Theory

The paper investigates an alternative approach to measuring and compensating reactive power in electric machines, particularly under non-sinusoidal voltage and current waveforms. Traditional power definitions, such as those introduced by Budeanu and Fryze, as well as the power triangle, are discussed alongside integral definitions of reactive power, which account for waveform distortions. This approach is novel and has not been previously applied in the context of electric machines. A digital algorithm for reactive power calculation, based on the integral definition, is proposed. It requires minimal computational resources and is easy to implement. Experimental measurements conducted on a single-phase induction motor demonstrate the impact of capacitive compensation on current waveforms. The results confirm the validity of the adopted definition of reactive power. With full reactive power compensation, the RMS value of the current drawn by the motor is minimized, which is not always the case with the classical approach to improving the power factor. The findings highlight the importance of accurate reactive power measurement and compensation in enhancing the performance and energy efficiency of electrical machines. The proposed approach is applicable not only to single-phase motors but also more broadly in determining the reactive power drawn by electric machines and in measuring electric energy, particularly in the presence of distorted voltages and currents.