Voltage estimation in power distribution networks. A case study on data aggregation and measurement uncertainty

The paper presents a real case study of uncertainty evaluation in case of data aggregation. The analysis is related to the half period rms voltage time aggregation stated by IEC 61000-4-30 for voltage measurement and it is based on selected data gathered during more than one year. In order to perform the measurements campaign, the special facility (OSC function) of custom designed equipment called MOT was used. The mix of measurement uncertainty, data aggregation and non-stationarity of data make the search of relevant information difficult. After a short introduction concerning relevant theoretical aspects of the measurement uncertainty evaluation and the aggregation process requirements according to the standards, the paper presents the measurement system. Estimation of the uncertainty is carried out with data gathered on two hypotheses: normal distribution of the measurement uncertainties associated with the half period rms voltage values and on experimental induced measurement uncertainties distribution. Conclusions and recommendations are drawn.