Analysis of electric metering of intermediate frequency furnace harmonics

The working principle of intermediate frequency furnace is introduced and the harmonic characters are analyzed in detail. The problem of a greater impact on electrical energy measurement of the higher harmonics produced by an intermediate frequency furnace ,which may cause huge economic losses. The fact that the power which harmonics are produced from the harmonic source user has an opposite direction to the fundamental wave has been demonstrated in theory in this article. On this basis, the impacts of harmonics on active electrical energy measurement have been studied, and a simulation model has also been built in MATLAB/simulink for an experiment. The experimental results have verified the correctness of theoretical analysis, and a form of electrical energy measurement that is suitable for harmonic source users of the intermediate frequency furnace has been proposed.

I. Introduction

In recent years, driven by market and economic interests, a growing number of intermediate frequency steelmaking furnaces have been used for production. In addition to frequent impacts on the power grid, their start/stop may also bring about harmonics damages which cannot be ignored any more. The intermediate frequency furnace converts three-phase power frequency AC into single-phase intermediate frequency AC by rectifiers and converters which are the core equipment of an intermediate frequency furnace [1]. This type of electronic devices will inevitably transmit a large number of harmonics to the power grid.