How to select an reactor for the inverter

- Jul 24, 2019-

The types of reactors are varied, the ideal reactor should have the following characteristics: no oil, no noise, small volume, good linearity, no leakage, strong overcurrent capacity, structural stability, strong weather resistance and so on. In general, we divide the reactor into two kinds: alternator (input reactor, output reactor), DC reactor, how should the user correctly select the reactor? Need to see what their role is, according to different circumstances to choose the corresponding reactor.

I. AC reactor  

What the input reactor does:Limiting the current shock caused by the sudden change of power grid voltage and the over-operated voltage, smoothing the spikes contained in the supply voltage, or the voltage defects caused by the smooth bridge rectification circuit changing phases, effectively protects the inverter and improves the power factor, which can not only prevent interference from the power grid, but also reduce the harmonic current generated by the rectifier unit to pollute the grid.

The role of the output reactor:    

Compensates for the influence of long-line (50-200m) distribution capacitors, and can suppress the output harmonic current, improve the output high-frequency impedance, effectively suppress the reduction of high-frequency leakage current, play a role in protecting the inverter, reduce the noise of the equipment. When the capacitor compensates for power, it is often affected by harmonic voltage and harmonic current, resulting in damage to the capacitor and reduced power factor.

2. DC reactor

The role of DC reactors:

DC reactor in the dc rectification link of the inverter system and the inverter link, the main role is to superimposed on the DC current AC component limited to a specified value, to maintain the continuous rectification current, reduce the current pulse of the punch value, so that the operation of the inverter more stable and improve the power factor of the inverter.

As a means of reactive compensation, the reactor is indispensable in the power system.

According to the wiring method can be divided into parallel reactor and series reactor, according to function can be divided into current-limiting reactor and compensatory reactor;

Parallel reactors are reactors connected in parallel to the system, mainly to compensate for capacitive currents.  In ultra-high voltage long-range transmission system, it is usually installed on the transformer's three coils to compensate for the capacitive charging current of long-distance transmission lines, to prevent the system from increasing the line-end voltage, to reduce the system over-operation voltage, in order to maintain the system voltage stability, improve the transmission capacity and efficiency of the system.

Series reactors, commonly known as damping reactors, are reactors connected in series to capacitor banks or intensive capacitor banks to limit the flow of switches.

The main function of series reactor is to suppress the high harmonic slower and limit the closing surge, to prevent the harmonic stoicor from causing harm to the capacitor, and to avoid the excessive amplification and harmonious vibration of the harmonics of the power capacitor device.