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. 50Hz to 5 kHz) are clarified. Hence, this paper presents the test and analysis of harmonic responses of High Voltage (HV) instrument voltage transformers. It firstly presents a proposed HV Voltage Transformer Frequency Response (VTFR) test bed and test method. Then, the harmonic response assessment of a single phase 400kV Wound-type Voltage Transformer (WVT) and a single phase 275kV Capacitor Voltage Transformer (CVT) are conducted using the developed test bed. Both the WVT and the CVT were tested at their rated fundamental voltages with harmonic injections from 100Hz to 5 kHz. Different burdens were connected to the WVT and the CVT in the tests. Test results were obtained, analyzed, compared and discussed.