Stray Parameter Evaluation of Voltage Transformers for PQ Measurement in MV Applications

Power Quality (PQ) monitoring is one of the key tasks in modern power systems. In transmission and distribution grids, PQ phenomena are often measured by inductive Voltage Transformers (VTs) installed for metering and/or protection applications. VTs accuracy requirements should be ideally met under actual operating conditions, which can differ from the calibration ones, in particular for the presence of environmental or circuital influence factors. The impact of such influence factors on the VT performance in PQ measurements is an open issue, not fully addressed in the literature. In this respect, this paper presents a simplified numerical-experimental model of inductive MV VTs, which can be used for the analysis of VT wideband behaviour in PQ applications, also in presence of one or more influence factors. The results provided by the model are experimentally validated and future applications are discussed.