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Voltage transformer harmonic characteristics for distribution power quality monitoring

Davis, P; Wright, P; King, J; Jupe, S; Pinkerton-Clark, S (2021) Voltage transformer harmonic characteristics for distribution power quality monitoring. In: CIRED 2021 - the 26th International Conference and Exhibition on Electricity Distribution, 20-23 September 2021, Online Conference.

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There is an increasing need to measure the increase in voltage harmonics associated with the power convertors used in low carbon technologies. Existing voltage transformers (VT) used for protection and measurement are often repurposed for harmonic monitoring despite only being characterised at 50 Hz. Previous research has shown that the VT ratio and phase angle between primary and secondary windings has a frequency dependant characteristic. This paper reports the testing of five VTs, typically used in UK distribution networks, characterised at low voltages up to 5 kHz. Only one of the VTs has an attenuation of ratio which could be easily corrected, the other four demonstrate some form of resonance between 3.5 kHz and 5 kHz, which in the worst case cause an incorrect measurement of up to 80% and a phase angle shift of over 80 degrees. A second set of measurements was completed changing the burden applied to the secondary winding of the VT, these tests demonstrated that loading the VT generally increased the phase difference and reduced the voltage ratio. This work forms part of a project funded by the Network Innovation Allowance that is made available by the energy regulator in Great Britain, Ofgem.

Item Type: Conference or Workshop Item (Paper)
Keywords: Voltage Transformer Frequency Response CIRED
Subjects: Electromagnetics > Electrical Measurement
Divisions: Electromagnetic & Electrochemical Technologies
Identification number/DOI: 10.1049/icp.2021.2058
Last Modified: 15 May 2023 13:37
URI: http://eprintspublications.npl.co.uk/id/eprint/9715

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