CN102074331B - Magnetic saturation reactor - Google Patents

Abstract

The invention relates to a magnetic saturation reactor capable of reducing the volume and weight of a magnetic saturation reactor under the condition of satisfying the performance requirement, and reducing the reactance value of the magnetic saturation reactor in a magnetic saturation state. It includes: a Japanese-shaped structure magnetically saturated reactor core; one side of the magnetically saturated reactor core is respectively equipped with a reactance coil L1 and a DC coil L2; the other side of the magnetically saturated reactor core is respectively installed with a reactance coil L3 and a DC coil L4; the end of the same name of the reactance coil L1 is one of the AC terminals I of the AC circuit of the magnetic saturation reactor, the opposite end of the reactance coil L1 is connected to the end of the same name of the reactance coil L3, and the opposite end of the reactance coil L3 is the magnetic saturation reactor Another AC terminal II of the AC circuit; the same-named end of the DC coil L2 is connected to the same-named end of the DC coil L4, and the different-named end of the DC coil L2 is one of the DC terminals I of the DC circuit of the magnetic saturable reactor, and the different-named end of the DC coil L4 The name end is another DC terminal II of the DC circuit of the magnetic saturation reactor.

Description

A magnetic saturation reactor

technical field

The invention relates to the field of power transmission and transformation in power systems, in particular to a magnetic saturation reactor.

Background technique

With the continuous development of the power system and the continuous increase of power generation capacity, the short circuit current caused by the short circuit of the power system is very large. The short circuit current caused by the short circuit in the power system is very harmful to the power system. When a short circuit occurs in the power system, the relay protection device issues a trip command to trip the circuit breaker and cut off the short circuit current. The ability of the circuit breaker to cut off the short-circuit current is limited. When the short-circuit current exceeds the maximum cut-off current value of the circuit breaker, the circuit breaker cannot cut off the short-circuit current. Therefore, reducing the short-circuit current can enable the circuit breaker to cut off the short-circuit current, reduce the degree of damage to the power equipment during short-circuit, and improve the stability of the power system.

In recent years, research on methods and devices for limiting short-circuit current (also known as current limiters) has become a hot topic.

The current limiter is formed by using the saturation characteristic of the iron core of the magnetic saturable reactor. A group of DC coils are added to the iron core of the magnetically saturated reactor. When the power system is operating normally, the DC power supply supplies DC current to the DC coil, which deeply saturates the iron core of the magnetically saturated reactor. When the iron core of the magnetically saturated reactor is deeply saturated, the magnetically saturated reactor presents a small reactance; the current limiter connected in series in the transmission line has no effect on normal power transmission. When a short circuit occurs in the power system, the control module cuts off the DC current of the DC coil, and the iron core of the magnetically saturated reactor is out of saturation; the magnetically saturated reactor presents a large reactance. The magnetic saturation reactor connected in series in the transmission line limits the short-circuit current and reduces the short-circuit current.

Patent No. 2008101604501 "a short-circuit current limiting device for a magnetically saturated reactor" and patent No. 2008101592788 "short-circuit current limiting device and method" are one of the research results in this regard. The magnetic saturation reactor is the core equipment of the magnetic saturation reactance current limiter, and it is also the most expensive equipment. Its characteristics directly affect the performance index of the current limiter. There are disadvantages in the structure of the saturable reactor used in the existing magnetic saturation reactance current limiter. How to reduce the volume and weight of the magnetically saturated reactor under the condition of meeting the performance requirements, and how to reduce the reactance value of the magnetically saturated reactor in the state of magnetic saturation is one of the research directions.

Contents of the invention

The object of the present invention is to solve the above problems and provide a magnetic saturation reactor that can reduce the volume and weight of the magnetic saturation reactor under the condition of meeting the performance requirements; in the magnetic saturation state, it can reduce the reactance value of the magnetic saturation reactor. saturable reactor.

To achieve the above object, the present invention adopts the following technical solutions:

A magnetic saturation reactor, which includes:

A magnetically saturated reactor core; the magnetically saturated reactor core is a Japanese-shaped structure; one side of the magnetically saturated reactor core is respectively installed with a reactance coil L1 and a DC coil L2; the other side of the magnetically saturated reactor core is respectively installed with a reactance Coil L3 and DC coil L4; the process requirements of the structure, number of turns and winding method of the reactance coil L1 and the reactance coil L3 are the same; the process requirements of the structure, number of turns and winding method of the DC coil L2 and the DC coil L4 are the same;

The end of the same name of the reactance coil L1 is one of the AC terminals I of the AC circuit of the magnetic saturation reactor, the opposite end of the reactance coil L1 is connected to the end of the same name of the reactance coil L3, and the opposite end of the reactance coil L3 is the AC circuit of the magnetic saturation reactor The other AC terminal II;

The end of the same name of the DC coil L2 is connected to the end of the same name of the DC coil L4, the end of the opposite name of the DC coil L2 is one of the DC terminals I of the DC circuit of the magnetic saturation reactor, and the end of the opposite name of the DC coil L4 is the DC circuit of the magnetic saturation reactor The other DC terminal II. the

The sun-shaped structure of the iron core of the magnetic saturation reactor takes the center line of the middle iron core as the axis and is symmetrical on both sides; the middle iron core forms a magnetic flux closed loop with one side of the iron core, and the middle iron core forms another Magnetic flux closed loop; the iron cores on both sides form a third magnetic flux closed loop; the cross-sectional areas of the iron cores on both sides are equal; the cross-sectional area of the middle iron core is greater than or equal to the cross-sectional area of one of the iron cores, but less than or equal to twice the The cross-sectional area of one side of the core.

The reactance coil L1 of the magnetically saturated reactor and the DC coil L2 are wound in layers; the reactance coil L3 of the magnetically saturated reactor and the DC coil L4 are wound in layers.

The reactance coil L1 and the reactance coil L3 are AC paths; the DC coil L2 and the DC coil L4 are DC paths.

The invention provides a magnetic saturation reactor structure and a connection method which can reduce the volume and weight of the magnetic saturation reactor under the condition of meeting the performance requirements; and reduce the reactance value of the magnetic saturation reactor in the magnetic saturation state.

The beneficial effects of the invention are: the iron core, the number of coil turns and the weight of the magnetic saturation reactor are reduced under the condition of satisfying the performance requirement; and the reactance value of the magnetic saturation reactor is lower in the magnetic saturation state. The magnetic saturation reactor of the present invention is used in a current limiter, and the voltage loss at both ends of the magnetic saturation reactor is reduced by 30% when the power system is in normal conduction operation.

Description of drawings

Figure 1 shows the structure and connection mode of the magnetic saturation reactor;

Figure 2 shows the internal and external hierarchical structure of the magnetically saturated reactor reactance coil and DC coil;

Among them, 1. AC terminal I, 2. AC terminal II, 3. DC terminal I, 4. DC terminal II, 5. Magnetic saturation reactor core.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The structure and connection mode of the magnetic saturation reactor are shown in Figure 1. The AC terminal I1 and the AC terminal II2 of the device are connected in series to the AC transmission circuit; the DC terminal I3 and the DC terminal II4 of the device are connected in series to the DC power supply circuit.

Since the end of the same name of the reactance coil L1 is the AC terminal I1 of the AC circuit of the magnetic saturation reactor, the end of the opposite name of the reactance coil L1 is connected to the end of the same name of the reactance coil L3, and the end of the same name of the reactance coil L3 is the terminal of the AC circuit of the magnetic saturation reactor. AC terminal II; and because the structure, number of turns, and winding method of the reactance coil L1 and the reactance coil L3 have the same technical requirements; therefore, the magnetic flux Φ1 generated in the iron core by the alternating current flowing through the reactance coil L1 and the reactance coil L2 flow The magnetic flux Φ2 generated by the alternating current in the iron core is equal in magnitude and opposite in direction. The AC magnetic flux will only flow in the third magnetic flux closed loop formed by the iron cores on both sides of the Japanese-shaped structure of the magnetic saturable reactor, and will not flow from the middle iron core of the Japanese-shaped structure of the magnetic saturated reactor. At present, the structure of the magnetically saturated reactor that has been used is a double-shaped structure, and the AC magnetic flux circulates in the two-shaped structures. The alternating magnetic flux path of the invention is shorter than the alternating magnetic flux path of the two-shaped structure magnetic saturation reactor that has been used at present. Under the same excitation current condition, the number of iron core and coil turns of the magnetic saturation reactor of the present invention can be reduced.

If the DC current of the DC coil L2 and DC coil L4 of the magnetically saturated reactor is zero; the iron core of the magnetically saturated reactor is out of saturation, and the reactance of the reactance coil L1 and the reactance coil L3 connected in series in the transmission circuit is very large.

The same-named end of the DC coil L2 is connected to the same-named end of the DC coil L4, the different-named end of the DC coil L2 is one of the DC terminals I3 of the DC circuit of the magnetic saturation reactor, and the different-named end of the DC coil L4 is the DC circuit of the magnetic saturation reactor DC terminal II4. Reactance coil L1 generates power-frequency magnetic flux in the core of the magnetically saturated reactor, and the power-frequency magnetic flux generates induced electromotive force in the DC coil L2; reactance coil L3 generates power-frequency magnetic flux in the core of the magnetically saturated reactor. The high-frequency magnetic flux generates an induced electromotive force in the DC coil L4; since the structure, number of turns, and winding method of the DC coil L2 and the DC coil L4 have the same process requirements, the power-frequency induced electromotive force of the DC coil L2 is the same as that of the DC coil L4. The generated electromotive force is subtracted to zero, and the AC current of the reactance coil L1 and the reactance coil L3 has no influence on the DC circuit. the

When a DC current flows through the DC coil L3, the middle iron core and the iron core on the side of the DC coil L3 form a closed loop of magnetic flux; when a DC current flows through the DC coil L4, the middle iron core and the iron core on the side of the DC coil L4 form a magnetic flux Closed loop; the two flux loops, completely covering the flux loop of the AC flux. Therefore, when the DC magnetic flux saturates the iron core, the iron core of the AC magnetic flux is also saturated at the same time. The iron core of the magnetically saturated reactor is in a saturated state, and the reactance of the reactance coil L1 and the reactance coil L3 connected in series in the transmission circuit is very small, which has no influence on the power transmission system.

When a DC current flows through the DC coil L3, a magnetic flux Φ3 is generated in the iron core; when a DC current flows through the DC coil L4, a magnetic flux Φ4 is generated in the iron core. Φ3 and Φ4 are equal in size and in the same direction; Φ3 and Φ4 flow through the middle iron core of the Japanese-shaped structure of the magnetically saturated reactor at the same time. The iron core of the magnetic saturation reactor has a Japanese-shaped structure with the middle iron core as the axis, and the two sides are symmetrical; the middle iron core forms a magnetic flux closed loop with one side of the iron core, and the middle iron core forms another magnetic flux closed loop with the other side iron core , the iron cores on both sides form the third magnetic flux closed loop. The cross-sectional areas of the iron cores on both sides are equal; when the cross-sectional area of the middle iron core is equal to twice the cross-sectional area of one side of the iron core, if the middle iron core is not saturated, the two sides of the iron core will not be saturated; if the middle iron core Saturation, the iron cores on both sides are also saturated at the same time; the ampere-turns of the DC coil L3 and the DC coil L4 are fully utilized. When the cross-sectional area of the middle iron core is less than twice the cross-sectional area of one side of the iron core, if the middle iron core is not saturated, the iron cores on both sides will not be saturated; if the middle iron core is saturated, the two side iron cores are not necessarily saturated. Saturation; if the iron cores on both sides are saturated, the middle iron core must be saturated; the ampere-turns of DC coil L3 and DC coil L4 are not fully utilized. Under the condition that the middle iron core is saturated but the iron cores on both sides are not saturated, it is necessary to increase the DC current to saturate the iron cores on both sides; or increase the number of DC coil turns without increasing the DC current to saturate the iron cores on both sides. The cross-sectional area of the middle iron core is less than twice the cross-sectional area of one of the iron cores, which reduces the weight of the iron core. If the cross-sectional area of the middle iron core is smaller than that of one of the iron cores on one side, the increase in the number of turns of the DC coil is more, and the gain outweighs the gain. Therefore, the cross-sectional area of the middle iron core is greater than or equal to the cross-sectional area of one side of the iron core, but less than or equal to twice the cross-sectional area of one of the side iron cores.

The DC coil L3 and the DC coil L4 can be replaced by a coil wound on the middle iron core of the magnetic saturation reactor. The advantage of this is to save a coil and reduce power consumption; the disadvantage is that the DC coil and the reactance coil The coupling is not close enough, when the DC coil flows through the DC current, the reactance drop of the reactance coil L1 and the reactance coil L3 connected in series in the transmission circuit is not good enough.

The AC coil and DC coil of the currently used magnetically saturated reactor are respectively wound on different iron core columns. Because the potential of the DC coil to the ground is low, the voltage difference between the AC coil and the DC coil is large; if the AC coil and the DC coil are wound on the same iron core column, a short circuit between the AC coil and the DC coil may occur , damage the equipment connected to the DC coil. The magnetically saturated reactor of the present invention is an accessory equipment of the "current limiting device and method with flexible switching characteristics" with the invention patent number: 2010105753926. In this invention, the DC coil has a high ground potential, and the gap between the AC coil and the DC coil The voltage difference is small; the AC coil and the DC coil are wound on the same iron core column, and the probability of short circuit between the AC coil and the DC coil decreases. In this invention, the potential of the equipment connected to the DC coil will automatically increase with the increase of the potential of the AC coil, and the equipment connected to the DC coil has high-voltage insulation measures against the ground. Will not damage equipment connected to the DC coil. Therefore, due to changes in the application environment, the structure of the magnetically saturated reactor can be different, and a magnetically saturated reactor structure with better performance can be invented. The AC coil and the DC coil of the magnetic saturation reactor of the present invention are layered wound on the same iron core column, which strengthens the magnetic coupling between the AC coil and the DC coil. The DC current of the DC coil saturates the iron core. Under the condition of iron core saturation, the reactance of the AC coil of the magnetic saturation reactor decreases less, and the adverse effect on the normal power transmission of the power system is smaller.

Figure 2 shows an internal and external hierarchical structure of the magnetic saturation reactor reactance coil and DC coil. The reactance coil L1 (L3) of the magnetically saturated reactor can be on the outer layer, and the DC coil L2 (L4) can be on the inner layer; or the reactance coil L1 (L3) of the magnetically saturated reactor can be on the inner layer, and the DC coil L2 (L4) can be on the outer layer; The magnetically saturated reactor reactance coil L1 (L3) and the DC coil L2 (L4) can be alternately layered.

The various components of the magnetic saturation reactor structure and connection method can be designed and manufactured with the prior art, and can be completely realized. It has broad application prospects.

Claims (3)

1. A magnetically saturated reactor, characterized in that it comprises: A magnetically saturated reactor core; the magnetically saturated reactor core is a Japanese-shaped structure; one side of the magnetically saturated reactor core is respectively installed with a reactance coil L1 and a DC coil L2; the other side of the magnetically saturated reactor core is respectively installed with a reactance Coil L3 and DC coil L4; The end of the same name of the reactance coil L1 is one of the AC terminals I of the AC circuit of the magnetic saturation reactor, the opposite end of the reactance coil L1 is connected to the end of the same name of the reactance coil L3, and the opposite end of the reactance coil L3 is the AC circuit of the magnetic saturation reactor The other AC terminal II; The end of the same name of the DC coil L2 is connected to the end of the same name of the DC coil L4, the end of the opposite name of the DC coil L2 is one of the DC terminals I of the DC circuit of the magnetic saturation reactor, and the end of the opposite name of the DC coil L4 is the DC circuit of the magnetic saturation reactor The other DC terminal II of the magnetically saturated reactor core; the sun-shaped structure of the magnetically saturated reactor core takes the middle line of the middle iron core as the axis, and the two sides are symmetrical; the middle iron core and one side of the iron core form a magnetic flux closed loop, The iron core on one side forms another magnetic flux closed loop; the iron cores on both sides form a third magnetic flux closed loop; the cross-sectional areas of the iron cores on both sides are equal; the cross-sectional area of the middle iron core is greater than or equal to the cross-sectional area of one of the iron cores, But less than or equal to 2 times the cross-sectional area of one side of the iron core; the reactance coil L1 and the reactance coil L3 are AC paths; the DC coil L2 and the DC coil L4 are DC paths; the AC coil and the DC coil are wound in the same layer On the iron core column; the magnetic flux Φ1 generated in the iron core by the alternating current flowing through the reactance coil L1 and the magnetic flux Φ2 generated in the iron core by the alternating current flowing through the reactance coil L3 are equal in magnitude and opposite in direction; The flux will only flow in the third closed loop of magnetic flux formed by the iron cores on both sides of the Japanese-shaped structure of the magnetically saturated reactor, and will not flow from the middle iron core of the Japanese-shaped structure of the magnetically saturated reactor. 2. A kind of magnetically saturated reactor as claimed in claim 1, characterized in that, said magnetically saturated reactor reactance coil L1 and DC coil L2 are wound in layers; magnetically saturated reactor reactance coil L3 and DC coil L4 are wound in layers system. 3. The magnetically saturated reactor according to claim 1, characterized in that, the structure, number of turns, and winding method of the reactor coil L1 and the reactor coil L3 are the same; the structure of the DC coil L2 and the DC coil L4 , number of turns, and winding method are the same.

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