Plenty of harmonics and inter-harmonics in the utility grid injected by fluctuating loads strongly have an im-pact on the safe and stable operation of power grid .According to GB/T 17626.30, there exist three kinds of measure-ment methods, namely class A、S and B, for each parameter measured, however, they are adopted by different instru-ments leading to the difference between measuring results in domestic power quality test instruments which become a long-standing issue .Based on the definition and algorithm of the three kinds of measurement methods of class A、S and B, this paper analyzes and compares the effects of the three kinds of measuring methods on harmonic analysis by their maximum value and 95%probability maximum value separately with the measured data of two typical fluctuating loads spot welder and EAF .Finally , from the perspective of practical engineering application , it proposes the applications and relevant conclusions for the three kinds of measurement methods respectively .%波动性负荷在运行过程中会向公用电网注入大量的谐波和间谐波,严重影响了电网的安全稳定运行.GB/T 17626.30规定对每一个待测参数都有Class A、S和B三类测量方法,而国内的电能质量测试仪器长期存在不同仪器采用不同测量方法导致测量结果互有差异的问题.基于Class A、S和B三类谐波测量方法的定义和算法,结合点焊机和电弧炉两种典型波动性负荷的实测数据,分析并对比了此三类测量方法在谐波测量中的最大值和95%概率大值的差异性.最后从实际工程应用的角度,给出了三类测量方法的适用场合和相关结论.
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