Frequency response test of MV inductive voltage transformers for power quality applications

Abstract

Power quality maintenance is a concern that has currently reached all levels of electric systems. This concern is mainly due to the increased connection of nonlinear devices and loads with high sensitivity to power quality disturbances on distribution, transmission and generation complexes. However, to enable power quality measurements on medium (MV) and high voltage networks, voltage transducers are necessary. There are different types of voltage transducers commercially available. The inductive voltage transformers (IVTs) are most commonly used for MV systems. However, it is well-known that some types of voltage transducers may not present a linear transformation ratio for harmonic frequencies, including IVTs. Therefore, to overcome this nonlinearity of voltage transducers, the IEC published a technical report addressing guidelines and recommendations regarding the use of instrument transformers for power quality applications (IEC/TR 61869-103). In this context, this paper is aimed at performing a frequency response test on three MV IVTs using the mentioned IEC document in order to guarantee accurate harmonic voltage measurements. Moreover, a laboratory structure at the Federal University of Uberlândia is implemented for evaluating the frequency response on MV transducers.