What Are The Differences Between Ac Reactors And Dc Reactors?

The common reactors used in power systems are AC reactors and DC reactors. AC reactors are mainly used to limit short-circuit currents. They are also connected in series or in parallel with capacitors in filters to limit high-order harmonics in the power grid. Reactors in 220kV, 110kV, 35kV, and 10kV power grids are used to absorb the charging capacitive reactive power of cable lines. The operating voltage can be adjusted by adjusting the number of DC reactors. Ultra-high voltage DC reactors have multiple functions to improve the operating conditions related to reactive power in power systems.

AC Reactors mainly includes:

(1) Capacitive effect on light no-load or light-load lines to reduce power frequency transient overvoltage.

(2) Improve voltage distribution on long transmission lines.

(3) Make the reactive power in the line as locally balanced as possible when light load is applied to prevent unreasonable reactive power flow and reduce power loss on the line.

(4) When large units are connected in parallel with the system, reduce the power frequency steady-state voltage on the high-voltage bus to facilitate synchronous parallel connection of generators.

(5) Prevent the self-excited resonance phenomenon that may occur when the generator carries a long line.

(6) When the neutral point of the reactor is grounded through a small reactor, the small reactor can also be used to compensate for the line phase-to-phase and phase-to-ground capacitance to accelerate the automatic extinction of the latent current, which is convenient for use.

Reactors are divided into AC reactors and DC reactors.

The function of the DC reactor is to limit the AC component superimposed on the DC current to a certain specified value. The filter reactor, also known as the DC reactor, is used on the DC side of the converter. The DC current with AC components flows through the reactor. The function of the DC reactor is to limit the AC component superimposed on the DC current to a certain specified value. It is also used for the DC side coupling of parallel converters to reduce the discontinuous limit and limit the circulating current in the circulating line. It is used to limit the current rise rate when the DC fast switch is used to cut off the fault current. It is also used in the DC smoothing of the intermediate circuit of the current and voltage type inverter, which can be used for rectifier power smoothing to eliminate ripple. Reduce the current pulsation value and improve the input power factor.

The role of AC reactor is

1. Reduce power supply harmonics, surge and peak current;

2. Increase low-frequency conduction resistance;

3. Protect drive mechanism of electrical and electronic components;

4. Increase power factor;

5. Prevent brake from falling due to voltage pulse of main power supply.

For engineering control automation industry, the input end of AC reactor inverter absorbs surge of power grid, operates overvoltage, protects equipment behind inverter, suppresses harmonic current of inverter, and increases speed.