Phase Detection Method Based on Harmonic and Unbalanced Voltage

This work proposes a phase detection approach capable of operating effectively under conditions involving harmonics and unbalanced voltages. Beyond the conventional PLL framework, the method incorporates dedicated compensation circuits for harmonic mitigation and unbalanced voltage correction. The harmonic compensation unit applies a specific-order harmonic extraction technique to remove undesired harmonic components from the input signal, while the power system frequency required for this extraction is obtained using an extended complex Kalman filter. For unbalanced conditions, the compensation circuit determines the positive-sequence component and performs normalization on the input voltage. With these enhancements, the proposed strategy delivers high-accuracy phase detection in environments affected by harmonic distortion and voltage asymmetry. Moreover, when voltage dips occur due to system faults, the method is still able to identify the positive-sequence voltage component. Simulation studies confirm the overall effectiveness of the proposed approach.