Study on Constraints for Harmonic Source Determination Using Active Power Direction

The traditional active power direction (APD) method has been proven to be unreliable to determine the dominant harmonic source at a point of common coupling (PCC), when both sides have the harmonic sources. In view of this shortcoming, this paper proposes an improved APD by imposing certain constraints to the traditional one. The constraints are developed based on the voltage and current measurements at the PCC and the impedance properties of the two sides. Through rigorous mathematical analysis, it has been proven that when those constraints are satisfied, the improved APD method is guaranteed to provide accurate results. Performance and effectiveness of the proposed method are demonstrated through simulation and field case verifications.