Difference between AC reactor and DC reactor
The common line reactors in electrical power system include series reactors and paralleling reactors. Series reactors are mainly used to limit short-circuit current or ultraharmonics in filter by connecting with capacitor in series or in parallel. The line reactors in power grid of 220kV, 110kV, 35kV and 10kV are used to absorb the idle work of charging capacity of cable line. Operating voltage can be adjusted by adjusting the number of line reactors in parallel. Ultra-high voltage paralleling reactor can improve the operation conditions relating to reactive power of electrical power system including:
- The capacitance effect on light load or no-load circuit lowers transient overvoltage of power frequency.
- Improve the voltage distribution on long power transmission line.
- Balance reactive power in light load circuit to prevent the unreasonable flow of reactive power and reduce the power loss on circuits.
- When large generator unit and system are in parallel, lower the steady-state voltage of power frequency on high voltage bus for the convenience in the synchronous parallel of generators.
- Prevent self-excitation resonance of generator with long line.
- When the neutral point of line reactor passes by grounding device, inter-phase or phase-ground capacitance of compensated line of easy-to-get small line reactor can be used to accelerate the automatic extinguishing of secondary arc current.
- The connection of line reactor is divided into series connection and parallel connection. Series reactor is generally used to limit current. And parallel reactor is generally used in reactive compensation.
DC line reactor is used to limit AC component on DC to a specified value. Filter reactor, also called DC smoothing reactor, is used at DC side of converter. The current in line reactor is direct current with AC component. It is used to limit the AC component on direct current to one specified value. It is also used in the coupling at DC side of parallel converter, DC flat wave of intermediate resonance circuit of voltage type frequency changer and flat wave of rectifier supply, to reduce intermittent limit, to limit the loop current in loop current circuit and the current rate of increase when DC fast switch breaks fault current, and to eliminate ripple wave. It is also used to reduce ripple quantity of current and improve input power factor.