How to shield power line harmonic interference from a power supply DTU?

Shielding against power line harmonic interference from the DTU requires a combination of filtering and digital processing. Active power filters (APFs) or passive filters are deployed at the power inlet to filter out specific harmonic frequencies (e.g., 3rd, 5th, and 7th harmonics). For the acquisition loop, an anti-aliasing filter is used, with the cutoff frequency set to half the sampling frequency. Digital processing employs FFT analysis and digital filtering algorithms to subtract harmonic components in real time. Harmonic content is monitored using a spectrum analyzer to optimize filter parameters. After shielding, the harmonic distortion rate (THD) should be less than 5% to ensure accurate metering and communication.