| Voltage harmonic content is an important index of evaluating the power equality.In recent years,with the comprehensive of smart grid in our country,large DC grid,solar power,wind power and other parallel operation.Which inject a large amount of harmonic in power grid.Harmonic not only reduce the performance of grid electricity transmission,but also damage to electrical equipment.Therefore,accurate measuring harmonic in power grid is of great significance.The traditional harmonic test method is installed in CVT secondary side harmonic analyzer,to measure the harmonic of power grid.But this method cannot reflect the reality of the grid side harmonic content right.How to accurately measure power grid harmonic is a problem to be solved.At first,this paper established the wide-band model of CVT.This article analyzes the key factors influencing the CVT transmission characteristics through simulation.From the simulation,equivalent stray capacitance reactor and a winding side of stray capacitance has a significant effect on CVT transmission characteristics.Compensation reactor equivalent resistance and load has a certain degree of influence on CVT transmission characteristics.The secondary winding of stray capacitance have little impact on CVT transmission characteristics.And then put forward the CVT model of wide-band application “Ghassemi transformer” technique for harmonic measurement.Installed in CVT primary side circuit to get the current amplitude transformer,further get harmonic voltage amplitude.In this paper the CVT wide-band model simulation and test.The simulation and experimental data show that the capacitive current method is used to measure the current waveform has certain distortion,which is more clearly describing high harmonic.The proposed method is better than the traditional method of measuring the actual value of side of the harmonic wave in the power grid.The method is simple and easy to operate,has the very good application prospect in the practical engineering. |
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