Transformer core remanence estimation analysis - 2019
30 15:05:59 power transformer no-load closing, will appear because of iron core saturation excitation inrush current, it can be turned into transformer excitation inrush current several times of the rated current.
With the increase of electric power transformer capacity, no-load switching-in excitation inrush current will become bigger, no-load switching-in excitation inrush current of the system, equipment safety and protection actions will produce certain effect, even will have serious consequences.
At present, multiple methods were used to inhibit the no-load switching-in of transformer excitation inrush current, such as: in the low voltage side of transformer with capacitor, resistance and interpolation methods such as synchronous close technology.
In addition to the synchronous close technical method, other methods have increased the complexity of equipment investment cost and operation.
Synchronous close technology is the core of the brake according to the points after the core switching time of the determination of the residual magnetism.
As long as the closing time, can avoid transformer iron core saturation of magnetic flux, can effectively inhibit the no-load switching-in of transformer excitation inrush current.
Forecast after transformer break-brake remanent magnetization in core is the key to realize synchronous close technology.
Mention a variety of remanent magnetism or the classic of the magnetic field calculation model and method, including the Preisach model, Produc model, Stoner -
But the above model calculation method involves some parameters cannot be directly measured, so in the transformer core remanence specific forecasts of practicality.
In order to make the transformer core remanence forecast to engineering practicability, can be transformer core remanence and transformer current amplitude and phase Angle of break-brake time, as long as access to the current amplitude and phase Angle of break-brake time of transformer and relationship characteristics of transformer core remanence, is based on the current amplitude and phase Angle of break-brake time of transformer and can estimate the transformer iron core remanence.
To get the word relationship characteristics, can transformer in drop test, or on the basis of the transformer no-load closing operation, record the different moment of break-brake current amplitude and phase Angle, different measuring points under the current amplitude and phase Angle of brake moment transformer core remanence.
As the abundance of records and measurement data and improvement of current amplitude and phase Angle of break-brake time of transformer and transformer core remanence relationship will be more easy to obtain.
After the transformer break-brake remanent magnetization in core proprietary instrument (usually by
Such as fluxmeter WB -
Measurement, but due to the measurement of the complexity of it is difficult to measure at the scene of the transformer operation.
But in practical engineering, on the premise of understanding transformer no-load closing Angle, the transformer no-load closing after detected in transformer primary side voltage current data, looking for transformer iron core saturation point, you can evaluate the magnetic of transformer core after break-brake left.