What are the Uses of the Reactor in Power System?
1.Restrict the short-circuit current
When the power system has short circuit, it will generate a very high short-circuit current. In order to guarantee the dynamic stability and thermal stability of the electrical equipment, the reactor is usually connected to the outgoing breaker in series, so as to increase the short-circuit impedance and restrict the short-circuit current. Because of the application of the reactor, the voltage drop on the reactor is high in case of a short circuit. It also plays the role of maintaining the voltage of the busbar, ensuring the small voltage fluctuation of the busbar and guaranteeing the operation stability of the electrical equipment on the non-fault line.
2.Restrict the higher harmonic
Because a large amount of power electronic devices have been used in the power system, especially high-power DC and frequency conversion equipment, which generate plentiful harmonics, the compensating capacitor is frequently damaged, and in serious conditions, the compensating capacitor is unable to be put into operation. When the harmonic is rather low, the harmonic suppressor can be used. When the harmonic in the power system is rather higher, the reactor in series can be adopted. The higher harmonic in the power grid can be restricted through connecting the capacitor in serious or parallel in the water filter.
Reactive balance is very important in enhancing the economic benefit of the power system and improving the power supply quality. Meanwhile, it is required to conduct dynamic regulation, and provide more capacitive reactiveness in load peak, so as to satisfy the reactive demand of the industrial and mining enterprises, stabilize the system voltage. On the other hand, it should be able to provide sensible reactiveness, so as to balance the charging power of the cables in fractional loading, ensuring the not too high voltage of the system. LC series circuit constituted by the capacitor and reactor in series has the function of restraining a certain frequency harmonic. Usually, the low-voltage series reactor is used to restrain the harmonics for three, four and five times.
4.Arc extinguish reactor
Arc extinguish reactor is connected between the neutral point and ground of the three-phase transformer. When one phase of the three-phase power grid is connected with the ground, the induction current can be supplied, so as to compensate the capacitive current flowing through the earthing point, enabling the nonflamability of the arc, so as to avoid having overvoltage caused by the repeated ignition of the arc. The arc extinguish reactor is widely used for the resonance earthing system of 6kV~10kV.
5.Phase shifting function
Phase shifting means that the waveform of the AC signal fails to change as the original angle and presents an angle change.The function of phase shifting reactor is to reduce the influence of the harmonic current and voltage generated by the semiconductor converter device and non-linear load to the power supply system. It is a new method for the converter power supply system to restrain the harmonic wave. Because in the three-phase symmetrical power supply system, generally the 5th, 7th, 11th, and 13th harmonics have greater contents and more serious influence to the system, the phase shifting electric reactor is designed to weaken these harmonics.
Input line reactor is mainly used in the industrial automation control to restrain the surge voltage and current generated by the frequency converter and speed regulator, so as to decay the high-frequency and distorted harmonics in the system to the greatest extent, limit the current impact caused by power grid voltage mutation and overvoltage operation.
Output line reactor is also called as the motor reactor. It is mainly used in the industrial automation system, especially occasions with frequency converter, to extend the valid transmission distance of the frequency converter, effectively restrain the transient high voltage in switching on/off the IGBT module of the frequency converter. It is suitable for compensating the distributed capacitance, restraining the output harmonic current, effectively protecting the frequency converter and improving the power factor, with an expectation to reduce the pollution of the harmonic current generated by the rectification unit to the power grid.