Parallel-Connected Voltage Generators for the Characterization of MV VTs up to 150 kHz

Recent advance in semiconductor technology has enabled the development of power converters with higher and higher switching frequencies. Some emerging technologies allow power converters to be directly connected to Medium Voltage (MV) power grids. Consequently, high-frequency components-specifically, harmonics related to the switching frequency-will be present within MV networks. To ensure the reliable and stable operation of these grids, it is essential that such disturbances are accurately measured. This scenario enhanced performance requirements on Instrument Transformers (ITs), particularly in terms of measurement accuracy over an extended frequency range. In order to properly assess ITs' frequency behaviour, it is crucial to implement a generation architecture, which allows to generate reduced-Amplitude spectral components up to hundreds of kilohertz superimposed to the power frequency component. Such an architecture is not currently available in the market and that is a huge gap between the actual state of the art and the metrological needs which have been emerging in recent years. In this paper, a generation setup for the characterization of Voltage Transformers (VTs) in the frequency range including power frequency (50 / 60 ~Hz) and spectral components within the range 9 kHz}-150 kHz is provided. The proposed architecture consists of two grounded and parallel-connected voltage generators to separate the generation of the power frequency component from the generation of high-frequency tones. Experimental results related to the working operations of the proposed architecture are discussed.