基于新过采样方法的APF电流THD测量

摘要

The current THD is an important index of active power filter(APF),it need that the THD is less than 5％after the compensation of APF.In practice,a variety of noise affects the THD value,during the A/D conversion,the maximum error of THD measurement can be 200％ ,which can not satisfy the need in industry application. As high power electronics equipment usually has low switching frequency, and the signal to noise ratio is indispensable in the THD calculation, a novel over-sampling method is presented.The theory is analyzed and some issues about the application of the new over-sampling method are discussed. Finally,the data sampled by the conventional method and the new method is compared to demonstrate the advantage of the proposed method and its validity.%电流总谐波畸变率(THD)是有源电力滤波器(APF)的一项重要性能指标,工业现场一般要求APF补偿后电流THD<5%ao实验发现A/D转换引入的噪声对THD测量影响极大,其误差可达200%,不能满足应用要求.针对大功率电力电子装置采样频率低和THD测量对采样信号信噪比要求高的特点,提出一种新的过采样方法,对其进行原理分析,进而结合THD测量的实际讨论了该方法应用的相关问题.最后,通过仿真和实验对传统采样方法和新过采样方法进行比较,验证了该方法的有效性.