What Are The Differences Between Ac Reactors And Dc Reactors?

The common reactors used in power systems are series reactors and shunt reactors. Series 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 shunt reactors. Ultra-high voltage shunt reactors have multiple functions to improve the operating conditions of power system reactive power, mainly including:

(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, the power frequency steady-state voltage on the high-voltage bus is reduced to facilitate synchronous parallel connection of generators. (5) Prevent the self-excited resonance phenomenon that may occur when the generator is connected to 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 phase-to-phase and phase-to-ground capacitance of the line to accelerate the automatic extinction of the latent current, which is convenient for use.

The wiring of the reactor is divided into two ways: series and parallel. Series reactors usually play a current limiting role, and parallel reactors are often used for reactive power compensation.

The DC reactor in the DC transmission system

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