Fast harmonic detection based on cascaded delayed signal cancellation PLL

Fast and accurate selective harmonic detection is crucial for many power harmonic compensation systems. The existing detection methods are known to have drawbacks such as the long delay time, the sensitivity to grid frequency variation, the difficulty to achieve zero steady-state error, etc. In order to overcome these drawbacks, this paper proposes a selective harmonic detection system based on the three-phase cascaded delayed signal cancellation phase-locked loop (CDSC-PLL). The system can be flexibly configured to detect any individual harmonic from the source with various background harmonics. It also features very short transient and insensitivity to frequency variations. The performance is verified by experimental results.