Watthour meters readings errors in presence of harmonies and active filters

Induction watthour meters are the most commonly used energy meters. Their records are subject to errors in the presence of harmonics due to its flux torque characteristics at different frequencies ,as these meters are designed to measure power in purely sinusoidal voltages and currents. This paper presents an analysis for the active power and energy measurements errors in induction watthour meters under nonsinusoidal voltages and currents waveforms. It proposes a design for an active filter to reduce harmonic contents and evaluate those errors in watthour meters readings with that active filter. The harmonic distortions of voltage and current are calculated before and after connecting the filter in order to indicate the influence of adding this filter on harmonic elimination situation. The written programs are general and can be used for power systems containing harmonic sources.