The impact of current transformers on measurement uncertainty of power quality
The impact of current transformer accuracy on the uncertainty of harmonic measurements was investigated. A literature review revealed the lack of traceability of harmonic measurements conducted using IEC 61869-2 or IEC 60044-1 compliant current transformers. Lack of traceability can be problematic for harmonic emission assessments conducted at South African independent renewable power plants (RPPs), as non-compliance to harmonic emission limits has legal implications. A test setup capable of measuring the harmonic frequency response of current transformers op to 3 kHz with 0.1% ratio and 0.02? phase displacement uncertainty was developed using off the shelf components. This setup was used to measure the harmonic frequency response of a number of current transformers installed at a solar PV farm in Southern Africa. Each current transformer showed a unique frequency response, even when supplied with an identical burden. The increase in measurement error with harmonic frequency can be compensated for by applying harmonic ratio correction factors and phase displacement corrections to harmonic measurements. The developed test set and test method can be used for future investigations into the harmonic frequency response of current transformers.
- Engineering