Integral Power Theory and Active Filtering Using the α-β Reference Frame

Abstract

The paper describes a new version of the integral power theory in the $\alpha - \beta $ reference frame, which combines the advantages of the well-known instantaneous and integral power theories, and a shunt active filtering strategy based on it. From p-q power theory, it takes the $\alpha - \beta $ reference frame and separation of instantaneous powers on average and oscillating components. The three-phase current decomposition of integral Currents’ Physical Components power theory in the frequency domain was improved by dividing the unbalance power component into two orthogonal components with separate integral unbalance powers. The method is proposed for determining these two integral unbalance power components using double fundamental frequency functions. This method was practically implemented by performing real-time algebraic operations with the instantaneous power oscillating components and $\alpha - \beta $ voltage coordinates synchronized with a three-phase network. Based on this current decomposition in $\alpha - \beta $ reference frame, the compensation three-component signal for shunt active filtering is proposed, each component of which is proportional to a separate integral inactive power. However, to save voltage and current sensors and avoid the need for a voltage reference point, the input and output information for the shunt active filter control system is set in the two-wattmeter reference frame. The proposed control system successfully passed the verification by computer simulation with selective compensation of the inactive power components. The suggested compensation algorithm has shown its effectiveness and reliability for a linear and even a non-linear load.

Keywords

• CPC power theory
• p-q power theory
• α-β reference frame
• power component decomposition
• unbalance power
• reactive power control