Current limiting and filtering effect of reactors
2023-04-14
The expansion of the grid capacity has led to a rapid increase in the rated value of the short-circuit capacity of the system. In order to limit the short-circuit current in transmission lines and to protect power equipment, reactors must be installed, which reduce the short-circuit current and keep the system voltage constant at the moment of the short-circuit.
Damping reactors (i.e. series reactors) are installed in the capacitor circuit, which acts as an inrush current suppressor when the capacitor circuit is put into operation. At the same time with the capacitor set together with the formation of harmonic circuit, play a role in the filtering of each harmonic. Such as in the 500kV substation 35kV reactive power compensation device in the capacitor circuit, in order to limit the inrush current when the capacitor is put into the capacitor and suppress the high harmonics of the power system, in the 35kV capacitor circuit must be installed damping reactor, suppress the 3rd harmonic, using the rated voltage 35kV, rated inductance 26.2mH, rated current 350A dry hollow single-phase outdoor type damping reactor, it forms a resonant circuit with the 2.52Mvar capacitor for the 3rd harmonic, i.e. the 3rd harmonic filter circuit.
Similarly, in order to suppress the 5th and higher harmonics, a single-phase outdoor type damping reactor with rated voltage 35 kV, rated inductance 9.2 mH and rated current 382A is used, which forms a resonant circuit with the 2.52 Mvar capacitor for the 5th and higher harmonics. It plays the role of suppressing high harmonics. It should be noted that the use and technical conditions of damped reactors are stipulated in the national standard "Reactors" GB10229-88 and the international standard IEC289-88. However, some domestic departments refer to damped reactors as series reactors, which is strictly speaking inappropriate, as neither of the above standards has the name series reactor.
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