CN102290200B - Controllable saturable reactor - Google Patents

Abstract

The invention relates to the field of electric power transmission and transformation, in particular to a controllable saturated reactor. It includes: a controllable saturable reactor core; the controllable saturable reactor core is a Japanese-shaped structure, with the center line of the middle core as the axis, symmetrical on both sides; the cross-sectional areas of the two side cores are equal, and the two sides Constitute a closed magnetic flux loop with equal cross-sectional area; one side of the iron core is respectively installed with a reactance coil L1 and a DC coil L2; the other side is installed with a corresponding reactance coil L3 and a DC coil L4; the reactance coil L1 and the The structure and the number of turns of the reactance coil L3 are the same; the structure and the number of turns of the DC coil L2 and the DC coil L4 are the same; Flow to the middle iron core; when the reactance coil flows through the AC current, the AC magnetic flux forms a flux loop between the iron core on the side where the reactance coil is located and the middle iron core. The middle iron core is a section of the AC magnetic circuit, and the other part of the AC magnetic circuit The iron core of the road section is shared with the DC magnetic flux; the magnetic resistance of the middle iron core road section is greater than that of other road sections of the AC magnetic circuit.

Description

A controllable saturable reactor

technical field

The invention relates to the field of electric power transmission and transformation, in particular to a controllable saturated 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. Therefore, reducing the short-circuit current can reduce the damage degree of 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 can be constructed by using the saturation characteristic of the saturable reactor core. A group of DC coils are added to the iron core of the saturable reactor. When the power system is operating normally, the DC power supply supplies DC current to the DC coil to deeply saturate the iron core of the saturable reactor. When the iron core of the saturable reactor is deeply saturated, the saturable reactor presents a small reactance; the current limiter connected in series in the transmission line has no effect on the normal 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 saturable reactor is out of saturation; the saturable reactor presents a large reactance. The saturated reactor connected in series in the transmission line limits the short-circuit current and reduces the short-circuit current.

The saturable reactor is the core equipment of the saturated reactance current limiter, and it is also the most expensive equipment. Generally, a double-port glyph saturated reactor is used. A magnetically saturated reactor (Patent No. 2010105840411), a saturable reactor body (Patent No. 2011100207304), a saturable reactor (Patent No. 2011100409541), and a low-noise saturable reactor (Patent No. 2011100409556), respectively proposed A variety of saturable reactors with their own characteristics. How to further reduce the volume and weight of the saturable reactor and reduce the price of the saturable reactance current limiter under the condition of meeting the performance requirements is one of the research directions.

Contents of the invention

The purpose of the present invention is to solve the above problems, to provide a current limiting effect by appropriately reducing the saturation reactance current limiter, but greatly reducing the volume and weight of the controllable saturated reactor, and greatly reducing the saturation reactance current limiter A controllable saturable reactor with better performance-to-price ratio between the current limiting effect and the price of the controllable saturable reactor.

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

A controllable saturable reactor, which includes:

A controllable saturable reactor iron core; the controllable saturated reactor iron core is a Japanese-shaped structure, with the center line of the middle iron core as the axis, symmetrical on both sides; the cross-sectional areas of the iron cores on both sides are equal, and the cross-sectional area Equal closed magnetic flux loops; one side of the iron core is equipped with a reactance coil L1 and a DC coil L2 respectively; the other side of the iron core is respectively equipped with a corresponding reactance coil L3 and a DC coil L4; the reactance coil L1 and the reactance coil L3 The structure and the number of turns are the same; the structure and the number of turns of the DC coil L2 and the DC coil L4 are the same;

When the DC coil flows through the DC current, the DC magnetic flux flows in a closed loop of magnetic flux formed by the iron cores on both sides, and the DC magnetic flux does not flow to the middle iron core; when the reactance coil flows through the AC current, the AC magnetic flux flows on the side where the reactance coil is located. A magnetic flux loop is formed between the iron core and the middle iron core. The middle iron core is a section of the AC magnetic circuit, and the other sections of the AC magnetic circuit share the iron core with the DC magnetic flux; the reluctance of the middle iron core section is greater than that of the other sections of the AC magnetic circuit The magnetic resistance.

The cross-sectional area of the middle iron core is less than the sum of the cross-sectional areas of the iron cores on both sides; the DC current of the DC coil is equal to zero, and when the voltage applied by the reactance coil is small, the middle iron core and the iron cores on both sides are not saturated; When the DC current is equal to zero and the rated voltage is applied to the reactance coil, the middle iron core is saturated, but the iron cores on both sides are not saturated.

The cross-sectional area of the middle iron core is smaller than the sum of the cross-sectional areas of the iron cores on both sides, and the cross-sectional area of a part of the middle iron core gradually decreases from large to small and then gradually increases; when the voltage applied by the reactance coil increases from small to small, The road section with a smaller cross-sectional area of the middle iron core is saturated first, and the road section with a larger cross-sectional area of the middle iron core is saturated later; the DC current of the DC coil is equal to zero, and when the voltage applied by the reactance coil increases to the rated voltage, the middle iron core is fully saturated, but The iron cores on both sides are not saturated.

The cross-sectional area of the middle iron core is less than the sum of the cross-sectional areas of the iron cores on both sides, and a part of the road section of the middle iron core is an air gap; the DC current of the DC coil is equal to zero, and when the voltage applied by the reactance coil is small, the middle iron core and the The iron cores on both sides are not saturated; the DC current of the DC coil is equal to zero, and when the rated voltage is applied to the reactance coil, the middle iron core is saturated, but the iron cores on both sides are not saturated.

The beneficial effects of the present invention are: when the controllable saturable reactor is connected in series in the power system and used as a series controllable saturable reactor, the volume and weight of the controllable saturable reactor can be greatly reduced, and the saturation reactance current can be greatly reduced The price of the limiter, the effect of limiting the current and the price of the controllable saturated reactor are more cost-effective. When the controllable saturable reactor is connected in parallel to the power system and used as a parallel controllable saturable reactor, the distortion of the voltage and current waveforms is small.

Description of drawings

Figure 1 shows a structure and connection method of a controllable saturable reactor;

Figure 2 shows the second structure and connection mode of the controllable saturated reactor;

Figure 3 shows the third structure of the controllable saturated reactor;

Figure 4 shows another form of the third structure of the controllable saturated reactor;

Figure 5 shows the fourth structure of the controllable saturated reactor;

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

Detailed ways

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

Example 1:

The structure and connection mode of the controllable saturable reactor are shown in Figure 1. It has a Japanese-shaped controllable saturated reactor core 5, and the AC terminal I1 and the AC terminal II2 are connected in series to the AC transmission circuit (composed of the reactance coil L1 and the reactance coil L2); the DC terminal I3 of the device is connected in series with the DC terminal II4 Connect to the DC power supply circuit (composed of DC coil L2 and DC coil L4).

Since the same-named end of the reactance coil L1 is connected to the same-named end of the reactance coil L3, it is one of the AC terminals I1 of the AC circuit of the controllable saturable reactor, and the opposite-named end of the reactance coil L1 is connected to the opposite-named end of the reactance coil L3. Another AC terminal II2 of the AC circuit of the saturable reactor; and because the structure and the number of turns of the reactance coil L1 and the reactance coil L3 are the same; therefore, the magnetic flux φ1 generated in the iron core by the alternating current flowing through the reactance coil L1 is equal to the reactance The AC current flowing through the coil L2 generates a magnetic flux φ2 in the iron core, which is equal in size and upward in direction. The AC magnetic flux goes upward on both sides of the Japanese-shaped structure, and passes through the middle iron core of the Japanese-shaped structure to form a closed circuit.

The opposite end of the DC coil L2 is connected to the opposite end of the DC coil L4, the end of the same name of the DC coil L2 is one of the DC terminals I3 of the DC circuit of the controllable saturable reactor, and the end of the same name of the DC coil L4 is a controllable saturable reactor DC terminal II4 of the DC link. Reactance coil L1 generates power-frequency magnetic flux in the iron core of the controllable saturable 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 iron core of the controllable saturable reactor, The power frequency magnetic flux generates an induced electromotive force in the DC coil L4; since the structure and number of turns of the DC coil L2 and the DC coil L4 are the same, the power frequency induced electromotive force of the DC coil L2 and the power frequency induced electromotive force of the DC coil L4 are subtracted as Zero, the AC current of the reactance coil L1 and the reactance coil L3 has no influence on the DC circuit. When the DC current flows through the DC coil L3 and the DC coil L4, the magnetic flux generated by the DC coil L3 and the DC coil L4 is upward and the other is downward, and the DC magnetic flux forms a magnetic flux closed loop in the iron cores on both sides; the DC magnetic flux makes the iron When the core is saturated, the iron core column where the AC coil is located is also saturated at the same time.

When the two DC coils flow through the DC current, the DC magnetic flux flows in the magnetic flux closed loop formed by the iron cores on both sides, and the DC magnetic flux will not flow to the middle iron core; when the two reactance coils flow through the AC current, the AC magnetic flux A magnetic flux loop is formed between the iron core on the side where the reactance coil is located and the middle iron core. The middle iron core is a section of the AC magnetic circuit, and the other sections of the AC magnetic circuit share the iron core with the DC magnetic flux; due to the cross-sectional area of the middle iron core Less than the sum of the cross-sectional areas of the iron cores on both sides, the reluctance of the middle iron core section is greater than the reluctance of other sections of the AC magnetic circuit.

If the DC current of the DC coil L2 and DC coil L4 of the controllable saturable reactor is zero, and the voltage applied between the AC terminal I1 and the AC terminal II2 is not enough to saturate the middle iron core of the Japanese-shaped structure, the controllable saturated reactance The iron core of the transformer is out of the saturation state, and the reactance of the reactance coil L1 and the reactance coil L3 connected in series in the transmission circuit is very large. If the DC current of the DC coil L2 and DC coil L4 of the controllable saturable reactor is zero; the voltage applied between the AC terminal I1 and the AC terminal II2 saturates the middle iron core of the Japanese-shaped structure, but the two sides of the Japanese-shaped structure When the iron core is not saturated, the reactance of the reactance coil L1 and the reactance coil L3 of the controllable saturable reactor connected in series in the transmission circuit decreases, but is still relatively large. Under the condition that the DC current of DC coil L2 and DC coil L4 is equal to zero, when the rated voltage is applied between AC terminal I1 and AC terminal II2, the iron cores on both sides of the Japanese-shaped structure are in a critical saturation state, and the controllable saturable reactor can be obtained Certain effect of limiting short-circuit current, and has smaller iron core volume and weight of controllable saturated reactor.

When the DC coil L2 and DC coil L4 of the controllable saturable reactor have a large DC current, the iron cores on both sides of the controllable saturable reactor are in a deep saturation state, and the reactance of the reactance coil L1 and the reactance coil L3 connected in series in the transmission circuit is very small . Due to the smaller core volume and weight of the controllable saturable reactor, the same DC flux can make the iron cores on both sides of the controllable saturable reactor more saturated, and the reactance value of the controllable saturable reactor is lower.

The reactance coil L1 and the reactance coil L3 are connected in parallel, and the high-order harmonic current can form a circulation loop in the reactance coil L1 and the reactance coil L3, so that the voltage waveform of the controllable saturable reactor is better. The high-frequency vibration generated by the iron core is small, and the noise generated by the controllable saturated reactor is small.

The reactance coil L1 and the DC coil L2 have the same column, and the reactance coil L3 and the DC coil L4 have the same column. If there is an interfering AC voltage between the DC terminal I3 and the DC terminal II4, a circulating current will be formed between the reactance coil L1 and the reactance coil L3. The interfering AC voltage between DC terminal I3 and DC terminal II4 is forced to drop. The harm of the interference voltage to the DC circuit is reduced.

When the DC coil L2 and DC coil L4 of the controllable saturable reactor have DC current, the iron cores on both sides of the controllable saturable reactor are saturated, but not deeply saturated; when the instantaneous value of the AC current of the reactance coil L1 and the reactance coil L3 is small, The iron cores on both sides are saturated, and the middle iron core is not saturated; when the instantaneous value of the alternating current of the reactance coil L1 and the reactance coil L3 is large, one of the iron cores on both sides enters an unsaturated state, and the middle iron core enters a saturated state; The instantaneous value of the AC current of the reactance coil L1 and the reactance coil L3 changes from small to large, the linearity of the reactance value is good, and the distortion of the voltage and current waveforms is small. In particular, when the controllable saturable reactor is connected in parallel to the power system and used as a parallel controllable saturable reactor, the distortion of the voltage and current waveforms is small, and the harmonics generated by the power system are small, which is of great significance.

Example 2:

Figure 2 shows the second structure and connection mode of the controllable saturable reactor; the end of the same name of the reactance coil L1 is one of the AC terminals I1 of the AC circuit of the controllable saturable reactor, and the end of the same name of the reactance coil L1 is the same as the end of the reactance coil L3 Terminal connection, the opposite end of the reactance coil L3 is another AC terminal II2 of the AC circuit of the controllable saturable reactor. The terminal with the same name of the DC coil L2 serves as the DC terminal I3, the terminal with the same name of the DC coil L2 is connected to the terminal with the same name of the DC coil L4, and the terminal with the same name of the DC coil L4 serves as the DC terminal II4.

In order to limit the overvoltage of the DC circuit and reduce high-order harmonics, in the structure and connection method shown in Figure 2, two short-circuit coils can be added to the two side columns, such as the patent No. 2011100409541 "a saturable reactor" adopted measures.

The structure and connection mode of the controllable saturable reactor shown in FIG. 2 can also obtain the effect of Embodiment 1.

Example 3:

Figure 3 and Figure 4 show the third structure and connection mode of the controllable saturable reactor; the reluctance of the middle iron core section of the controllable saturable reactor is greater than the reluctance of other sections of the AC magnetic circuit, and the cross-sectional area of the middle iron core is less than The sum of the cross-sectional areas of the iron cores on both sides, and the cross-sectional area of a part of the middle iron core gradually decreases from large and then gradually increases; It is saturated first, and the section with a larger cross-sectional area of the middle iron core is saturated later; because the saturation of the cross-sectional area of the middle iron core changes gradually, the distortion of the current and voltage waveforms is small, and the generated harmonics are small. The DC current of the DC coil is equal to zero, and when the voltage applied by the reactance coil increases to the rated voltage, the middle iron core is fully saturated, but the iron cores on both sides are not saturated.

Figure 3 shows that the cross-sectional area of a part of the middle iron core gradually decreases from large and then gradually increases, which is realized by the gradual thinning of the outer dimension of the middle iron core; Figure 4 shows that the cross-sectional area of a part of the middle iron core gradually decreases from large to small It gradually increases again, and it is realized by gradually increasing the size of the cavity inside the middle iron core. The method shown in Figure 4, when the section with a smaller cross-sectional area of the iron core is saturated first, the magnetic flux leakage is distributed in the inner space of the iron core, the spatial distribution characteristics of the magnetic flux leakage are better, and the characteristics of the controllable saturable reactor are better.

The structure of the controllable saturable reactor shown in FIG. 3 and FIG. 4 and the connection mode of each coil are the same as those in Embodiment 1, and will not be repeated here.

Example 4:

Figure 5 shows the fourth structure and connection mode of the controllable saturable reactor; the reluctance of the middle iron core section of the controllable saturable reactor is greater than the reluctance of other sections of the AC magnetic circuit, and the cross-sectional area of the middle iron core is smaller than that of the iron cores on both sides. The sum of the cross-sectional areas of the cores, and a part of the middle core section is an air gap; the characteristics of the saturated reactor are closer to a straight line, the current and voltage waveforms are less distorted, and the generated harmonics are smaller. When the DC current of the DC coil is equal to zero and the voltage applied by the reactance coil is small, the middle iron core and the iron cores on both sides are not saturated; the DC current of the DC coil is equal to zero, and when the rated voltage is applied to the reactance coil, the middle iron core is saturated, but the two iron cores are saturated. The side core is not saturated.

The structure of the controllable saturable reactor shown in FIG. 5 and the connection mode of each coil are the same as those in Embodiment 1, and will not be repeated here.

The controllable saturated reactor of the present invention can be designed and manufactured with the prior art, and can be completely realized. It has broad application prospects.

Claims (3)

1. controllable transducer is characterized in that it comprises:

A controllable transducer iron core; The controllable transducer iron core is a day font structure, is axle with middle iron core center line, bilateral symmetry; The sectional area of both sides iron core equates that the both sides iron core constitutes the sealing flux loop that sectional area equates; Reactance coil L1, dc coil L2 wherein are installed respectively on the iron core of a side; Corresponding reactance coil L3, dc coil L4 are installed respectively on the opposite side iron core; Reactance coil L1 and reactance coil L3 structure, the number of turn are identical; Dc coil L2 and dc coil L4 structure, the number of turn are identical;

When dc coil flow through direct current, the direct current flux magnetic flux closed loop that iron core forms in both sides flowed, iron core in the middle of direct current flux can not flow to; When reactance coil flow through alternating current, exchange flux formed flux loop between reactance coil place side iron core and middle iron core, and middle iron core is a section of interchange magnetic circuit, and it is shared to exchange other highway section iron cores of magnetic circuit and direct current flux; The magnetic resistance in middle iron core highway section is greater than the magnetic resistance that exchanges other highway sections of magnetic circuit;

The sectional area of said middle iron core is less than the sectional area sum of both sides iron core, and the part in middle iron core highway section is an air gap; The direct current of dc coil equals zero, and the voltage that applies of reactance coil hour, and middle iron core and both sides iron core are all unsaturated; The direct current of dc coil equals zero, and reactance coil is when applying rated voltage, middle core sataration, but the both sides iron core is unsaturated.

2. controllable transducer as claimed in claim 1 is characterized in that, the sectional area of said middle iron core is less than the sectional area sum of both sides iron core; The direct current of dc coil equals zero, and the voltage that applies of reactance coil hour, and middle iron core and both sides iron core are all unsaturated; The direct current of dc coil equals zero, and reactance coil is when applying rated voltage, middle core sataration, but the both sides iron core is unsaturated.

3. controllable transducer as claimed in claim 1 is characterized in that, the sectional area of said middle iron core is less than the sectional area sum of both sides iron core, and the sectional area in middle iron core part highway section is by increasing gradually again after diminishing greatly gradually; The voltage that reactance coil applies is during by little increase, and the long-pending less highway section of middle core section is earlier saturated, and is saturated behind the long-pending bigger highway section of middle core section; The direct current of dc coil equals zero, and when the voltage that reactance coil applies increased to rated voltage, middle iron core was all saturated, but the both sides iron core is unsaturated.

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