Reactor reactor Relies on the inductive reactance of coils to hinder current changes in electrical appliances. Divided into 7 kinds according to use: 1 Current limiting reactor. Connected in series with the power circuit to limit the value of the short circuit current. 2 shunt reactors. It is usually connected between the end of the EHV transmission line and the ground and acts as a reactive power compensator. 3 Communication reactors. Also known as a wave trap. In series with the transmission line for the communication line, used to block the carrier signal into the receiving device. 4 arc suppression reactor. Also known as arc suppression coil. Connected between the neutral point of the three-phase transformer and the ground to supply inductive current when one phase of the three-phase power grid is grounded to compensate for the capacitive current flowing through the ground point so that the arc does not ignite easily and thus eliminates Overvoltage due to repeated reignition of the arc. 5 filter reactor. It is used to reduce the amplitude of the ripple on the bamboo current in the rectifier circuit; it can also form a circuit with a capacitor to resonate at a certain frequency to eliminate the voltage or current of a certain harmonic of the power circuit. 6 furnace reactor. In series with the furnace transformer, limit its short circuit current. 7 Start the reactor. In series with the motor, limiting its starting current.
I. Reactor concept
Reactors are also called inductors. When a conductor is energized, it will generate a magnetic field in the space it occupies, so all current-carrying electrical conductors have a general sense of sensitivity. However, the inductance of the long straight conductor is small, and the generated magnetic field is not strong. Therefore, the actual reactor is a wire wound into a solenoid form, called a hollow reactor; sometimes in order to allow the solenoid to have a larger inductance, Then insert the iron core in the solenoid, said iron core reactor. The reactance is divided into inductive reactance and capacitive reactance. The more scientific classification is that the reactor (inductor) and the reactor (capacitor) are collectively referred to as a reactor. However, since the inductor was previously used and it is called a reactor, Nowadays, what people call a capacitor is a reactor, and a reactor is an inductor.
According to the structure and the cooling medium, according to the connection method, according to the function, according to the purpose of classification.
1 According to structure and cooling medium: divided into hollow type, core type, dry type, oil-immersed type, such as dry type air-core reactor, dry type iron core reactor, oil-impregnated iron core reactor, oil-impregnated air-core reactor, clamping Dry type air-core reactors, wrapped-type dry type air-core reactors, cement reactors, etc.
2 according to the connection: divided into shunt reactor and series reactor.
3 Press Function: It is divided into current limit and compensation.
4 According to use: subdivided according to specific purposes, such as current limiting reactor, filter reactor, smoothing reactor, power factor compensation reactor, series reactor, balance reactor, grounding reactor, arc suppression coil, line reactance Devices, line reactors, saturable reactors, self-saturated reactors, variable reactors (adjustable reactors, controllable reactors), yoke reactors, series resonant reactors, parallel resonant reactors, etc.
Reactor as a means of reactive power compensation is indispensable in the power system.
Shunt reactors: Reactors for generator full-load tests are the prototype of shunt reactors. Because of the attraction of the alternating magnetic field between the core cakes, core-type reactors generally have a noise level that is about 10dB higher than a transformer with the same capacity.
Current-limiting reactors: Current-limiting reactors are generally used for distribution lines. The branch current feeders from the same bus line often have a series of current limiting reactors to limit the short-circuit current of the feeder and maintain the bus voltage so as not to be too low due to the short circuit of the feeder.
Damping reactors (also commonly referred to as series reactors) are connected in series with capacitor banks or dense capacitors to limit the closing current of the capacitor. In this point, the action is similar to that of a current-limiting reactor. Filter reactor A filter reactor and a filter capacitor are connected in series to form a resonator filter, which is generally used for 3 to 17 times of resonance filtering or higher-order high-pass filtering. Converter stations for HVDC transmission lines, phase-controlled stationary compensation devices, medium and large-sized rectifier devices, and electrified railways, so that all power-electronic circuits controlled by high-power thyristors are harmonic current sources, and must be filtered out to prevent them from entering. system. The power sector has specific provisions for harmonics in the power system. p
Arc-suppression coils: Arc-suppression coils are widely used in resonant grounding systems of lOkV-6kV class. Because of the non-oiling tendency of substations, many arc-extinguishing coils below 35kV are now dry cast.
Smoothing reactor: Smoothing reactor is used in the DC circuit after rectification. The number of pulse waves in the rectifier circuit is always limited, and there is always a ripple in the output straight voltage. This ripple is often detrimental and needs to be suppressed by smoothing reactors. The HVDC converter stations are equipped with smoothing reactors, so that the output DC is close to the ideal DC. In the DC-powered thyristor electric drive, smoothing reactors are also indispensable.
DC-controlled saturable reactor: a turbulent or self-saturating saturable reactor stringed in a circuit. Within the period of a voltage sine wave, the saturable reactor absorbs a certain volt-second before reaching saturation, after which it is saturated. Fully open. Therefore, its output voltage is non-sinusoidal. This saturable reactor acts like a thyristor.
The main components of the electrical circuit are resistors, capacitors, and inductors. The inductors have the effect of suppressing the change of the current, and can make the phase shift of the alternating current. The winding-type static induction device having an inductance is called a reactor.
The role of reactor
The series of reactors and shunt reactors are common in reactors used in power systems. The series reactor is mainly used to limit the short-circuit current, but also in the filter in series or in parallel with the capacitor used to limit the higher harmonics in the power grid. Reactors in 220kV, 110kV, 35kV, and 10kV grids are used to absorb the capacitive charging and reactive power of cable lines. The operating voltage can be adjusted by adjusting the number of shunt reactors. The UHV shunt reactor has a variety of functions to improve the power system reactive power related operating conditions, including:
(1) Capacitance effects on light no-load or light-load lines to reduce the transient overvoltage of the power frequency.
(2) Improve the voltage distribution on long-distance transmission lines.
(3) Make the reactive power in the line at light load balance as much as possible to prevent irrational flow of reactive power and also reduce the power loss on the line.
(4) When the large units are in parallel with the system, the steady-state voltage of the power frequency on the high-voltage bus is reduced, which is convenient for the generators to be side by side during the same period.
(5) Prevent self-excitation resonance phenomenon of generators with long lines.
(6) When reactor neutral point is used as a small reactance grounding device, a small reactor can also be used to compensate the phase-to-phase and ground capacitance of the line to accelerate the submerged current automatically and extinguish it for ease of use.
Reactor connection points in series and parallel two ways. Series reactors usually act as current limiters, and shunt reactors are often used for reactive power compensation.