Earthing Transformer
A three-phase neutral grounding transformer with a winding connection according to the Zigzag scheme.
blockType: AcausalElectricPowerSystems.Passive.Transformers.Earthing
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Description
Block Earthing Transformer It is a three-phase neutral grounding transformer with a winding connection according to the Zigzag scheme. This unit allows you to create an artificial neutral in an ungrounded three-phase power supply system. The artificial neutral creates a low-resistance path for the zero-sequence current and a high-resistance path for the direct sequence current. The presence of a common point allows the use of a voltage source connected according to the Triangle scheme to connect a single-phase load.
For more information about the operating modes of a three-phase system connected according to the Triangle scheme, see Recommendations for delta connection of transformer windings.
The equations
This unit is implemented in both the electrical and magnetic fields, representing the physics of phase windings and a magnetic core. An equivalent block diagram includes blocks Reluctance, Winding and Eddy Current.
When connecting the windings in a zigzag, phases a, b, and c represent each rod of the magnetic core.
The relationship between electrical and magnetic properties can be obtained by applying several mathematical steps based on the rule of conservation of magnetic flux and Ohm’s law for a magnetic circuit.
For grounding transformers, the connections between the phases and all windings are the same.
In the equations below:
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— the number of turns of the winding.
-
— magnetizing resistance between phases.
-
— leakage resistance of the primary winding.
-
— the conductivity of the eddy current loop between the phases.
Then the relationship between the inductance matrix in the electrical domain and the inductance matrix in the magnetic domain can be written as:
The diagonal elements are the sum of the scattering inductance and the magnetizing inductance for each phase, so that:
Therefore:
Parameters
Main
Rated apparent power — rated full power
100e6 In*A (default)
The rated power passing through the transformer. The value must be greater than 0.
Rated voltage — RMS line voltage
24E3 V (default)
The nominal RMS line voltage.
The value must be greater than 0.
Rated electrical frequency — rated electrical frequency
50 Hz (default)
The nominal or nominal frequency of the AC network to which the transformer is connected. The value must be greater than 0.
Units — pass unit sy\$
\$ pu (default) | SI
A system of units for parameterization of impedance.
Dependencies
The use of other parameters depends on the value of this parameter.
Zero-sequence resistance, pu — zero sequence resistance
0.01 (default) | positive scalar
Resistance of the zero sequence in O.E.
The value must be greater than 0.
Dependencies
To use this parameter, set the Units parameter to Per unit.
Zero-sequence reactivity, pu — reactivity of the zero sequence
0.3 (default) | positive scalar
The reactance of the zero sequence in the O.E. Value must be greater than or equal to the magnetic flux losses of the primary winding.
Dependencies
To use this parameter, set the Units parameter to Per unit.
Shunt magnetizing resistance, pu — magnetization resistance of the core
500 (by default) | positive scalar
The magnetization resistance of the core in the O.E. Value must be greater than 0.
Dependencies
To use this parameter, set the Units parameter to Per unit.
Shunt magnetizing reactance, pu — magnetic inductance of the transformer core
500 (default) | positive scalar
The magnetic inductance of the transformer core must be greater than 0 when operating in its linear range.
Dependencies
To use this parameter, set the Units parameter to Per unit.
Zero-sequence resistance — zero sequence resistance
0.0576 ohms (default)
Zero sequence resistance. The value must be greater than 0.
Dependencies
To use this parameter, set the Units parameter to SI.
Zero-sequence induction — zero-sequence inductance
1.728 Gb (default)
The inductance of the zero sequence. The value must be greater than 0.
Dependencies
To use this parameter, set the Units parameter to SI.
Shunt magnetizing resistance — magnetization resistance of the core
2880 ohms (default) | positive scalar
The magnetization resistance of the core . The value must be greater than 0.
Dependencies
To use this parameter, set the Units parameter to SI.
Shunt magnetizing induction — magnetic inductance of the transformer core
2880 Gn (default) | positive scalar
The magnetic inductance of the transformer core when operating in its linear region. The value must be greater than 0.
Dependencies
To use this parameter, set the Units parameter to SI.