Reduction of Static Electricity Meter Errors by Broadband Compensation of Voltage and Current Channel Differences

To compensate for the different transfer functions of the current and voltage input stages of static electricity meters, usually, a time correction is applied, which is suitable for sinusoidal signals. However, for highly distorted signals, in which the high-frequency content is significant, this method is insufficient and reading errors will not be fully compensated. For such waveforms, this article describes two alternative methods to deal with the different input stages. The methods are implemented on a home-built waveform recorder, modified as static electricity meter, and validated using their influence on energy-reading errors for various waveforms and input stages (impedance and coupling). Apart from highly distorted current signals, also the effect of finite source impedance is considered by modifying the voltage waveform accordingly, which potentially influences the observed meter errors as well. The inverse-filtering method is the most powerful method but is computationally intensive and, therefore, more suitable for high-accuracy power meters than for inexpensive electricity meters. The less computationally intensive equivalent-filtering method shows very good results as well and is a better candidate to be implemented in electricity meters. The latter is especially relevant because of recent results, showing that some electricity meters are sensitive to specific disturbances beyond the present standard test waveforms.