Impact of interharmonics on the measurement error of AC sampling

Interharmonics exists in power system and it brings negative effect to power quality. The problem of interharmonics has received more and more attention. The paper investigates the impact of interharmonics on measurement error of ac sampling, which is widely used in power data acquisition system. The research reveals that interharmonics, even if its amplitude is small, will bring considerable error, and makes it impossible for data acquisition instruments to assure acceptable accuracy. Traditional one-period sampling method could do little to reduce the measurement error, even if it traces the supply fundamental frequency and increases the sampling rate. The paper suggests adopt multi-period sampling to reduce the negative effect of interharmonics and measurement error. Simulation validates the effectiveness of the proposed method.