The Core for High-Precision Stochastic Smart Grid Meter Based on Low-Resolution Flash ADC

This paper describes a mixed-signal multibit stochastic flash analog-to-digital conversion (ADC) and a stochastic measurement instrument based on it, as an alternative for standard sampling ADC. It provides precise measurements based on high-speed low-resolution flash ADCs with added statistical process (dither noise) that compensates for low resolution. Stochastic instrument for measurement of average value of the product of two signals, based on this method, is analyzed for multibit case, with estimation of upper limit of standard and relative measurement uncertainty. Working prototypes of 2- and 4-bit stochastic instruments are presented and compared. Precision of this instrument is user controlled—the longer the period of measurement, the higher is the measurement precision. This enables measurements of electrical quantities in a smart grid (SG), such as electrical energy, with high precision over long time intervals, and root-mean-square (RMS) voltage and RMS current over shorter time periods but with lower precision. A preview of a stochastic SG meter design is given. The working prototype of the 4-bit instrument has 0.0080% expanded measurement uncertainty (with the confidence interval of 95% and the coverage factor
$k = 2$
).