An Alternative Approach for THD Assessment

Abstract

In a grid, electrical installations operate under strict conditions to power quality, such as low harmonic emission, a balanced three-phase voltage, stable frequency, and a voltage level at consumer buses. Harmonic emission, mostly caused by non-linear loads, may lead to different well-known negative effects. However, some consumers are not able to operate with zero-emission, which leads to some consensus when a part of this emission to the grid is allowed. In order to compare the normalized and actual emission levels, and for quantitative assessment, in IEEE's and different national standards (in Russian Federation, USA, and EU countries, etc.), it has been introduced a factor named total harmonic distortion factor (THD). This paper outlines an approach for THD calculation, based on the operator-matrix state variable method (OMSV method).