Frequency dependent transfer characteristics of HV instrument transformers – state of the art

Summary

Due to the changing situation in the electrical power grid, the requirements for the electrical assets are changing as well. The rising presence of nonlinear components and power electronics result in higher distortion levels in the electrical grid and thus in a changing power quality. The measurements of the system voltage in the medium and high voltage grid are typically performed with inductive (IVT) or capacitive voltage transformers (CVT). The performance and accuracy of these instrument transformers is at present only specified for rated frequency. As accuracy at higher frequencies is of increasing importance, different research activities have already studied the frequency dependent transfer characteristics of IVTs and CVTs. Based on a literature review this paper summarizes the used methodologies and findings and identifies existing gaps challenges. Advantages and disadvantages of different test setups are discussed and recommendations on the efficient and accurate measurement of frequency responses with focus on HV voltage instrument transformers (VTs) are provided.

Additional informations

Keywords

Voltage Transformer, Harmonics, High Frequency, Accuracy