Errors in Digital Measurement of Voltage, Active and Reactive Powers and an on-Line Correction for Frequency Drift

In this paper, errors in digitally measured power system variables under non-ideal conditions namely, off-nominal frequency, finite word length sampling and harmonics are obtained by simulation. A new and efficient correction term for errors due to frequency drift is derived theoretically and its effectiveness is also illustrated. All the simulations are performed on a personal computer using LOTUS 123 spreadsheet (Copyright Lotus Development Corporation) with 16 bit integer arithmetic and 12 bit integers as input from the analog to digital conversion.