Self-Calibrating Harmonic Current Transformer Based on Gap Core Coil

Abstract

The invention discloses a self-calibration harmonic current transformer based on a gapped iron core coil. The transformer can output digital quantity and voltage simulation quantity which are linearly proportional to primary current containing harmonics, and can achieve the purposes of measurement and protection. The self-calibration harmonic current transformer comprises a gapped iron core, a primary coil, a measurement secondary coil, a protection secondary coil, a calibration coil, a monitoring secondary coil, an annular shielding box with a slotted inner ring, a first resistor, a second resistor, a third resistor, a sampling resistor, a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a first bidirectional voltage regulator tube, a second bidirectional voltage regulator tube, a third bidirectional voltage regulator tube, a fourth bidirectional voltage regulator tube, a signal conditioning circuit, an analog-to-digital converter, a microprocessor, a digital-to-analog conversion circuit, a calibration current drive circuit, a communication interface, and a first integral summation circuit and a second integral summation circuit which use a lossy integrator.

Description

technical field [0001] The invention relates to an electromagnetic measuring device, in particular to a self-calibrating harmonic current transformer based on an iron core coil with a gap for dual purposes of measurement and protection. Background technique [0002] Current transformer is a kind of current sensor, which is mainly used for grid electric energy measurement, electric energy quality analysis and safety protection. The national standard GB 1208-2006 "Current Transformer" and GB / T20840.8-2007 "Transformer Part 8 Electronic Current Transformer" stipulate the technical specifications of electromagnetic current transformer and electronic current transformer respectively. The national standard GB / T14549-1993 "Power Quality Harmonics of Public Grid" and the national standard GB / T19862-2005 "General Requirements for Power Quality Monitoring Equipment" respectively stipulate the allowable value, detection method and current harmonic monitoring equipment of public grid ha...

AI Technical Summary

Problems solved by technology

The disadvantage of this technical solution is that the use of air gap and shielding coil can only reduce the influence of leakage magnetic field so that the iron core is not suitable for saturation, but it cannot overcome the problem of narrow measurement frequency band and can only be used under power frequency

The disadvantage of this technical solution is that although the air-core coil is wound on the skeleton, there will still be changes in its geometric dimensions due to factors such as ambient temperature during long-term operation, which will seriously affect the accuracy of current detection.

Images