ESTIMATION OF QUANTIZATION ERROR IN MEASUREMENT OF ROOT-MEAN-SQUARE VALUES OF SINE SIGNALS
Authors: Khramkin Ivan A. ,   Novosibirsk State Technical University, Savinykh Maxim A. , Ponomarev Stanislav V. ,   Novosibirsk State Technical University,   Novosibirsk State Technical University
Published: August 2024

Relevance In modern electric power industry, digital measuring devices are often used, which are based on the use of analog-to-digital converters (ADCs). Manufacturers of such devices face the choice of an ADC, in particular, the choice of its key characteristic – the resolution. In the context of measuring devices, the share of the cost of the ADC is one of the main ones in the cost of the final device. At the same time, manufacturers often lay down the ADC with the largest number of resolution binary digits, while obtaining an unreasonably high margin in the number of bits. The issue of choosing the resolution of the ADC based on the quantization error is quite simply solved when measuring constant signals, however, in the case of variable periodic signals, this problem is often solved by a rough theoretical estimate, which leads to the use of an ADC with a higher resolution than would be necessary. The relevance of this work lies in the development of a proprietary method for solving the problem of estimating the error of quantization of ADCs, which will help developers of modern digital meters select ADCs with the minimum necessary characteristics for their devices, depending on the specified measurement range and accuracy class. Aim of research To develop a method for estimating the quantization error when measuring the root-mean-square values of sinusoidal signals, which includes a mathematical model of the measurement process and a software package that allows you to study the dependencies of the quantization error on the characteristics of the ADC and the shape of the signal under study. Research methods To perform this work, a mathematical modeling method was used with subsequent implementation in the form of a software package written in the LabVIEW language. The article presents a flowchart describing the algorithm of the program, as well as formulas and parameters used to simulate the measurement process and calculate errors. Results A mathematical model of the measurement process has been developed, implemented in a software package in the LabVIEW language. A number of experiments have been carried out investigating the dependence of the quantization error on the number of effective binary digits of the ADC. The main research results are expressed in the comparison of ADCs with a resolution of 16, 18, 20, 22 and 24 bits in the context of application for measuring AC power frequency in a digital transformer. The character of the change in the quantization error with a change in the signal magnitude is investigated. The results also prove the absence of an explicit dependence of the quantization error on the type of approximation used in the ADC. The method considered in this paper allows for an analytical assessment to select the minimum effective bit depth of the ADC. The conducted research is relevant when choosing an ADC for use in a measuring device.