Exploring The Impact Of Inductive Current Transformers On Harmonic Emission Measurements For South African Grid Code Compliance

Abstract

There have been various revisions of the South African Grid Code for Renewable Power Plants. This paper specifically focuses on the harmonic emissions component of the Grid Code, and how inductive current transformers (commonly used in outdoor substations) can impact the accuracy of these measurements. This paper considers inductive burden and harmonic current amplitude as two components to consider. An increased ratio error is introduced when lower current harmonic amplitudes are measured, typically below 0.5 A. An even greater ratio error is experienced when inductive burdens are connected to the secondary circuit of the current transformers. Conducting measurements and quantify the burden at each site is of importance, while also determining its influence on measurements when conducting harmonic current analysis for Grid Code compliance. Once quantified, these errors can be compensated for to improve the accuracy of these harmonic current measurements.