Digital method for power frequency measurement using synchronous sampling

An approach to the design of a digital algorithm for measuring AC values (current, voltage, phase, power, energy, frequency), based on usage of slow, highly precise and low-cost analogue/digital converters (dual-slope) is described. Measurements of voltage and current are performed more than once in a period, so the measured value is reconstructed after n periods. The algorithm presented is of an adaptive type in accordance with harmonic content of the input signal. Measurements performed in a real system (electric power system or electrical utilities) in Yugoslavia indicate that the voltage waveform remains unchanged while the required accuracy is maintained.