| Electronic transformer plays an important role in the smart substation, it can sample the electrical signal of the Grid primary side, and convert it into a specific protocol of digital fiber optic signal for secondary intelligent units. In the categories of electronic transformer there is a kind of electronic current transformer based on rogowski coil, it consists of rogowski coil, collector and merging units.Found in the process of actual operation of smart substation, electronic current transformer based on rogowski coil can produce additional dynamic component under some special conditions, and the additional dynamic component is likely to unexpectedly lead to the mal-operation of a line differential protection.When the problem above appears on electronic current transformer based on rogowski coil, a smart substation field test method which researches the dynamic characteristics of electronic current transformer arises at the historic moment. Power amplifier has played a key role in the smart substation field test method and is alse the main research object of this thesis. Because power amplifier can be as a replacement for rogowski coil in test method, its performance directly affects the effectiveness and accuracy of the test method.To meet the specific requirements of the smart substation field test based on a research about the dynamic characteristics of electronic transformer, this paper developed four kinds of specific large voltage power amplifier using existing technology, There were ± 30 V double op-amps series amplifier, ± 30 V current feedback amplifier, ±30V voltage feedback amplifiers and ±100V voltage feedback amplifier. By using these power amplifiers this research subject completed a dynamic test and a differential protection test of the smart substation field test. It is verified that electronic current transformer based on rogowski coil can produce additional dynamic component under certain conditions, and the additional dynamic component will affect the actions of line differential protection. |
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