Test and analysis of harmonic responses of high-voltage instrument voltage transformers

Conventional instrument voltage transformers are currently used as the essential instrument for harmonic measurement in power network. However, their frequency bandwidths are limited. As a result, they are not suitable for high frequency harmonic measurement unless their frequency responses in a concerned frequency range (e.g. 50 Hz to 5 kHz) are clarified. Hence, this presentation desribes the testing and analysis of the harmonic responses of high-voltage (HV) instrument voltage transformers. It firstly presents a proposed HV voltage transformer frequency response (VTFR) testbed and test method. Then, the harmonic response assessments of a single-phase 400-kV wound-type voltage transformer (WVT) and a single-phase 275-kV capacitor voltage transformer (CVT) are conducted using the developed testbed. Both the WVT and the CVT were tested at their rated fundamental voltages with harmonic injections from 100 Hz to 5 kHz. Different burdens were connected to the WVT and the CVT in the tests. Test results were obtained, analysed, compared and discussed.