Harmonic compensation of induction watthour meter performance

This paper analyzes the variation of the registration error of an induction watthour meter (IWHM) with respect to those parameters concerning the harmonic characteristics of the load and harmonic performance of the IWHM. Based on an analysis of the results of error variation, two types of compensation methods, namely, meter external methods and meter internal methods, are proposed to improve the accuracy of the IWHM when operated in harmonic situations. The meter external methods are related to the harmonic characteristics of the load, while the meter internal methods are associated with the harmonic performance of the IWHM. Each compensation method is comprised of several measures. This paper presents these measures for each compensation method, and gives detailed illustrations of the practical aspects for each measure. The feasibility of each compensation method is assessed, and some useful suggestions for utilities, users and manufacturers of IWHMs are offered. The study results show that the registration error due to constant single power harmonic interference can be fully compensated. When multiple power harmonics exist, however, the compensation, in general, can only focus on the main harmonic component to reduce the registration error to as low as possible. The effectiveness of those compensation methods which are feasible has been confirmed by the experimental results.