JP2009177012A - Dc reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC reactor to be serially connected to the rectifier of a DC transforming station for electric railway which can be prevented from rapid increase of current flowing, at the occurrence of a fault and which can reduce the high-frequency waves generated due to rectification. <P>SOLUTION: The DC reactor 1 to be connected to a rectifier 25 of a DC transforming station 20 for electric railway has a coil 2, having a size necessary for suppressing the inductance in the air-core state that can cut off the rise of fault current, at the occurrence of an accident by a circuit breaker, and also has a magnetic core 3 which is to be inserted to the coil so that the inductance in the rated current region of 2,000 A or higher can reduce the rectification ripples generated that accompany rectification. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC reactor connected in series with a rectifier in a DC substation for electric railways and installed on the return line side.

  Conventionally, in a DC substation for electric railways, a cored DC reactor with a gap has been installed in series on the return line side. This DC reactor is connected in series with the rectifier of the substation, thereby suppressing the rectification ripple generated from the rectifier. Moreover, this DC reactor suppresses a fault current that flows transiently from becoming a large current when a ground fault or the like occurs near a substation. In particular, the cored DC reactor with a gap has a core and has a relatively large inductance even if it is small, and is suitable for being placed in a limited space in a DC substation for electric railways.

  FIG. 10 is a diagram showing the relationship between the current flowing through the gap-core iron core type DC reactor and the inductance. As shown in FIG. 10, the DC core reactor with a gap has a rated value of 1.1 to 1.3 mH when the current flowing therethrough is around the rated current (4000 A), but 8000 A is reduced. When a large current exceeding the current flows, the iron core has a magnetic saturation, and the inductance rapidly decreases to 0.3 mH or less.

  Therefore, when a DC core reactor with a gap is used in a substation with a relatively large capacity, when a low-resistance ground fault occurs, the core causes magnetic saturation due to the large transient fault current, and its inductance decreases. As a result, the current increases rapidly, which has the disadvantage of affecting the breaking performance of DC substation equipment, particularly DC high-speed air circuit breakers.

  Therefore, in recent years, air-core DC reactors have been installed in DC substations for electric railways. This air-core DC reactor prevents a sudden increase in fault current without causing a decrease in inductance even when a large transient fault current such as a low-resistance ground fault occurs near a substation. it can.

  However, the air core type DC reactor has a problem that the device becomes very large when trying to obtain an inductance equivalent to that of the conventional gap cored DC type reactor. For this reason, the minimum inductance (0.4-0.5 mH) required for the DC substation for electric railways was ensured.

  FIG. 11 is a diagram showing the relationship between current flowing through a conventional air-core DC reactor and inductance. As shown in FIG. 11, in a conventional air-core type DC reactor, although a decrease in inductance does not occur even when a large current is passed, compared to a gap-core iron core type DC reactor in the vicinity of the rated current (4000 A). Inductance must be reduced, and the effect of suppressing rectification ripple generated from the rectifier is reduced accordingly. Therefore, there is a problem that a load is imposed on the power filter to suppress this rectification ripple. Furthermore, in the air core type DC reactor, the fault current that flows when a ground fault occurs etc. increases faster than the conventional gap cored DC reactor from the beginning of the accident, so by the time the breaker interrupts the fault current. There is also a problem that the fault current reaches a high current value.

  FIG. 12 is a diagram showing an increase in fault current in a conventional DC reactor. As indicated by the one-dot chain line in FIG. 12, the air core type DC reactor has a lower inductance at low currents than the gap cored DC reactor, so at the initial stage of the failure, the gap cored DC shown by the solid line is shown. The fault current increases faster than the reactor. On the other hand, the DC core reactor with a gap has a magnetic saturation when the current flowing through the core exceeds 8000A, and the inductance decreases sharply. Therefore, the fault current also increases rapidly, and the air core type DC reactor is reached at about 10 ms. Will cause more fault current to flow.

  In other words, when a fault current is interrupted by a circuit breaker, the wear current can be reduced by minimizing the fault current that increases between the occurrence of a ground fault and the like until the circuit breaker starts to open. However, it is difficult to sufficiently suppress an increase in the fault current when either a conventional gap-core iron core type DC reactor or an air core type DC reactor is used. That is, there is a problem that the circuit breaker is worn out correspondingly and the safety at the time of breaking is lowered.

  The present invention has been made in consideration of the above-mentioned matters, and an object of the present invention is for an electric railway which can prevent a sudden increase in current flowing when a failure occurs and can reduce rectification ripple caused by rectification. It is to provide a DC reactor that is connected in series with a rectifier of a DC substation and installed on the return side.

  In order to solve the above-mentioned problem, the first invention is a DC reactor connected in series with a rectifier of a DC substation for electric railway and installed on the return line side, wherein an inductance in an air-core state is a fault current at the time of occurrence of an accident. In order to reduce the rectification ripple generated by rectification, the winding is the size necessary to suppress the rise to a size that can be interrupted by the circuit breaker, and the inductance in the rated current region of 2000 A or more, There is provided a DC reactor having a magnetic core inserted into the winding.

  According to the DC reactor configured as described above, the rectification ripple generated by rectification at the rated current can be reduced by inserting a magnetic core in the winding, even if the size is the same as that of an air-core DC reactor. An inductance as high as possible can be obtained. Furthermore, when a fault such as a ground fault occurs, a transient fault current flows, but the DC reactor must maintain a high inductance from the time of the fault until the fault current significantly exceeds the rated current. Therefore, the rise of the fault current can be kept low.

  In addition, if the fault current that flows transiently becomes a large current that greatly exceeds the rated current as a short time elapses after the failure occurs, the magnetic substance in the magnetic core is magnetically saturated, and the inductance of the DC reactor decreases. To do. However, since the winding is to secure the inductance necessary to suppress the rise of the fault current when the accident occurs even in an air-core state to a level that can be interrupted by the circuit breaker, an accident occurs when an accident such as a ground fault occurs. Since the rise of the fault current that occurs between the time when the fault is detected and the fault current is cut off using a circuit breaker, etc. is kept lower than that of conventional DC reactors, the fault current can be shut off more safely and reliably by the circuit breaker. can do.

  A second invention is a DC reactor connected in series with a rectifier of a DC substation for electric railway, comprising a winding and a magnetic core inserted into the winding, and having an inductance in a rated current region of 2000 A or more Is 1.1 to 1.3 mH, and the inductance of the current region in which the magnetic core is magnetically saturated is 0.5 to 0.7 mH (Claim 2).

  According to the DC reactor having the above-described configuration, even if the magnetic core is inserted into the winding and is about the same size as the air-core type DC reactor, the rated current is about twice that of the air-core type. A high inductance of 1 to 1.3 mH can be obtained. Therefore, the rectification ripple generated from the rectifier can be effectively suppressed. In order to obtain the effect of reducing this rectification ripple, 1.1 mH or higher is better. However, by suppressing it to 1.3 mH or less, the loss due to the DC reactor is reduced and the installation area, cost, etc. The effect can be increased.

  Furthermore, when a fault such as a ground fault occurs, a transient fault current flows, but the DC reactor must maintain a high inductance from the time of the fault until the fault current significantly exceeds the rated current. Therefore, the rise of the fault current can be kept low. In addition, if the failure current becomes a large current that greatly exceeds the rated current as time passes after the failure occurs, the magnetic material in the magnetic material core is magnetically saturated and the inductance is reduced, but the winding is in an air-core state. However, since it can maintain 0.5 to 0.7 mH, which is more than twice that of a conventional cored DC reactor with a gap, even if the magnetic core is completely saturated, The rise can be kept lower than before.

  In the first and second inventions, most of the rectifiers of DC substations for electric railways perform full-wave rectification of three-phase alternating current, so the 6th, 12th, 18th, etc. harmonic components appear as ripples. However, by using the direct current reactor of the present invention, it is possible to suppress the rectification ripple and perform stable power supply with little ripple at a current near or below the rated current.

  The magnetic core preferably includes two legs and a yoke to form an annularly connected magnetic path, thereby reducing leakage of magnetic flux that does not pass through the winding. . Moreover, it is preferable to use a pair of windings disposed on two legs and connected in parallel to each other. That is, since almost the same amount of magnetic flux flows through the two legs of the magnetic core, it can be divided in a balanced manner between the two windings arranged so as to be wound around each leg, and the DC reactor Current capacity can be increased. Moreover, it is preferable that the magnetic body which comprises a magnetic body core is what laminated | stacked the silicon steel plate with a low loss and a high saturation magnetic flux density, for example.

  In the case where the magnetic core is a gap core core in which a plurality of core blocks made of a ferromagnetic material and a plurality of paramagnetic blocks interposed between the core blocks are alternately stacked (Claim 3). As a direct current reactor, necessary and sufficient inductance can be obtained. Further, the gap increases the linearity of the nonlinear magnetic characteristic (hysteresis) of the magnetic core, and a stable inductance can be obtained for continuous use.

  By using the DC reactor of the present invention for a DC substation for electric railways, it is possible to achieve both reduction of rectification ripple and suppression of fault current by the inductance set double according to the magnitude of the DC current flowing through it. It is said. In other words, the DC reactor has a high inductance of about 1.1 to 1.3 mH in a normal use state in which the rated current is passed through the rectifier, so that the rectification ripple can be suppressed and a sufficiently smoothed current can be output. it can.

  Furthermore, if a fault current that greatly exceeds the rated current flows when a fault occurs, at least an inductance of the winding in the air-core state of 0.5 to 0.7 mH can be secured, so that the circuit breaker fails from the time of the fault occurrence. The rise of the fault current that increases until the current is cut off can be made as small as possible. In addition, since the DC reactor has a large inductance immediately after the occurrence of the fault current and until the fault current greatly exceeds the rated current, the rise of the fault current can be further delayed. In other words, the lower the failure current that the circuit breaker breaks, the higher the safety at the time of breaking and the longer the life of the circuit breaker, so that the maintenance of the circuit breaker can be performed easily.

Next, an embodiment showing a configuration of a DC reactor of the present invention will be described with reference to the drawings.
1-3 is a figure which shows the structure of the direct current reactor 1 concerning 1st Embodiment of this invention, and as shown in FIG. 1, the direct current reactor 1 of this embodiment is a pair of windings connected in parallel This is a dry coil having a rated current of 4000 A, having 2A, 2B and a magnetic core 3 inserted into the windings 2A, 2B.

  The windings 2A and 2B are connected in parallel, and the shape thereof is formed in a cylindrical shape so that the conductors of each part are arranged in a circle as much as possible, and is configured to keep the shape with high strength. Yes. In the following description, the entire two windings 2A and 2B connected in parallel are referred to as a winding 2.

  As shown in FIG. 2, each winding 2A, 2B has an average diameter D of 800 to 1100 mm and a width W of 250 to 280 mm. Then, when the winding 2 is in an air-centered state, an inductance of 0.5 mH to 0.7 mH is obtained as the size of the inductance necessary for suppressing the rise of the fault current at the time of the accident to a level that can be interrupted by the circuit breaker. The number of turns and the height H of each of the windings 2A and 2B are designed so that

  As shown in FIG. 3, the magnetic core 3 includes a pair of leg portions 3A and 3B and a yoke portion 3C that connects the upper and lower ends of both leg portions 3A and 3B. It is a core core with a gap to be formed. Each of the legs 3A and 3B has a plurality of iron core blocks 10 made of a ferromagnetic material having a rectangular cross section and a plurality of paramagnetic material blocks 11 made of a paramagnetic material interposed between the iron core blocks 10 alternately. It is formed by laminating.

  In addition, it is preferable that the said iron core block 10 is laminated | stacked through the insulating layer between the some silicon steel plates which made iron contain silicon in order to block an eddy current. The manufacturing cost can be reduced because the cross-sectional shape of the magnetic core 3 is rectangular, but the cross-sectional shape of the iron core block 10 is nearly circular by stacking silicon steel plates of different sizes. As a thing, it is good also considering the cross-sectional shape of leg part 3A, 3B of the magnetic body core 3 as substantially circular.

The cross-sectional area of the iron core block 10 is 900 to 1000 cm ² , and the size and number of the iron core blocks 10 and the paramagnetic blocks 11 constituting the legs 3A and 3B are inserted in the winding 2. In this state, the inductance in the region of the rated current 4000A of the winding 2 is increased. The magnetic core 3 of the present embodiment is configured so that, for example, the rated current is 4000 A, and the inductance of the winding 2 in the rated current region is 1.1 mH as an example of a magnitude that can reduce the rectification ripple generated due to rectification. Has been.

  The DC reactor 1 uses, for example, air as its insulating medium. However, insulating oil or insulating gas may be used as the insulating medium.

  FIG. 4 is a diagram showing a list T1 in which the sizes of the winding and the iron core in the DC reactor of the present embodiment are compared with those of a conventional gap cored DC reactor having a rated current of 4000A. As shown in this comparative list T1, when the dry coil has the same rated current of 4000A, the average diameter Dp of the winding is about 650 mm and the width of the winding is 200 to 230 mm in the conventional cored DC reactor with a gap. In contrast, in the DC reactor 1 of this embodiment, the average diameter of the winding 2 is 800 to 1100 mm, and the width W is 250 to 280 mm. As described above, the DC reactor 1 of the present embodiment has the average diameter D and the width W of the windings 2A and 2B slightly increased as compared with the conventional gap-core iron core type DC reactor. The inductance at can be increased.

  FIG. 5 is a diagram for explaining the configuration of the electric railway DC substation 20 using the DC reactor 1. As shown in FIG. 5, a DC substation 20 for electric railway is connected to a rectifier transformer 21 that serves as a power source, and full-wave rectified to provide a return line 23 that is electrically connected to a train 22 as a load. A rectifier 25 for supplying DC power between the feeders 24, a power filter 26 connected in parallel with the rectifier 25, and a DC high-speed air circuit breaker 27 (hereinafter referred to as a DC high-speed air circuit breaker 27) provided on the feeder 24 side of the rectifier 25. And a fault detector 28 that shuts off the circuit breaker 27 when a fault current is detected by measuring a current flowing through the feeder 24 and the like. The DC reactor 1 of this embodiment is connected in series to the return line 23 side of the rectifier 25.

  Next, the operation of the DC reactor 1 of the present invention will be described with reference to FIGS. FIG. 6 is a diagram showing the relationship between the current flowing through the DC reactor 1 and the inductance of the present embodiment. As shown in FIG. 6, when the DC reactor 1 according to the present embodiment has a rated current of 4000 A or less, the inductance of the DC reactor 1 can be 1.1 mH or more. Therefore, when the electric railway substation 20 is operating normally, the DC reactor 1 should sufficiently reduce the 6th, 12th, 18th harmonic components generated by the rectifier 25 during rated operation. Can do.

  FIG. 7 shows the effect of suppressing the harmonic components of the 6th, 12th, 18th, and 24th ripples at the rated operation of the DC reactor 1 of the present embodiment. It is a figure which shows the list table T2 compared with the conventional air-core type DC reactor. As shown in FIG. 7, in the DC reactor 1 of the present embodiment, the harmonic components of the 6th, 12th, 18th, and 24th ripples are 30.0A, 7.1A, 3.7A, 2. Since it can be reduced by 1 A, it can be seen that the same harmonic component suppression effect as that of a conventional gap cored DC reactor can be obtained. Therefore, the capacity of the smoothing power filter 26 installed between the feeder line 24 and the return line 23 should be the same as that of the conventional gap cored DC reactor. it can.

  On the other hand, when a fault such as a ground fault or a short-circuit accident occurs as shown by an arrow F in FIG. 5, a transient large current tends to flow immediately after the occurrence of the fault. As shown in FIG. In the DC reactor 1 of the configuration, the inductance in the rated current region is 1.1 mH or more, and even if the magnetic core 3 is magnetically saturated, it does not fall below the inductance in the air-core state of the winding 2.

  That is, the winding 2 is configured so as to obtain an inductance of 0.5 to 0.7 mH necessary for suppressing the rise of the fault current at the time of the accident to a size that can be interrupted by the circuit breaker even in the air-core state. Therefore, the DC reactor 1 of this embodiment can maintain an inductance of 0.5 to 0.7 mH even if the magnetic core 2 is completely magnetically saturated.

  FIG. 8 is a diagram showing a transient increase in the fault current flowing through the DC reactor 1 when the DC reactor 1 of the present embodiment is used in the DC substation 20 for electric railways. As shown in FIG. 8, since the direct current reactor 1 can maintain an inductance of about 1.1 mH immediately after the occurrence of a failure until about 6 ms, the direct current reactor 1 of the present embodiment shown by a solid line is the conventional one shown by a virtual line. As with a DC core reactor with a gap, it increases more slowly than a conventional air core DC reactor indicated by a one-dot chain line. And in the region where the fault current exceeds 8000 A and the magnetic core 3 is magnetically saturated, it shows a relatively steep current increase due to the decrease in inductance, but not as much as the conventional gap cored DC reactor indicated by the phantom line, The current increases at a rate similar to that of a conventional air-core DC reactor indicated by a one-dot chain line.

  Therefore, by using the DC reactor 1 of the present invention, the rise of the fault current can be suppressed smaller than when any conventional type DC reactor is used.

  FIG. 9 is a diagram showing a list T3 in which the magnitude of the loss of the DC reactance of 1.1 mH is compared at the rated current of 4000 A of the gap type iron core type DC reactor 1 of the present embodiment and other conventional methods. As shown in FIG. 9, since the cored DC reactor 1 with a gap of this embodiment uses a magnetic core 3, compared to other conventional air-core DC reactors and magnetically shielded air-core DC reactors. The loss is small. For this reason, when the inductance in the rated current region is the same, the size of the DC reactor 1 of the present invention can be reduced as compared with the DC reactor of the conventional configuration of the air core type or the magnetic shielding air core type. .

  In the above-described embodiment, the DC reactor 1 having an inductance of 1.1 mH in the region of the rated current of 4000 A and an inductance of 0.5 to 0.7 mH in the current region in which the magnetic core 3 is magnetically saturated is illustrated. The present invention is not limited to this size. That is, if the rated current is a large DC reactor of 2000 A or more, it can be used in order to obtain the effect of suppressing the rise of the fault current by being connected in series to the rectifier of the electric railway DC substation.

  Further, if the inductance in the rated current region is in the range of 1.1 mH to 1.3 mH, it is possible to suppress a decrease in efficiency due to loss. Furthermore, the winding 2 may be one in which the two windings 2A and 2B are connected in series, or may be a single winding. In addition, any of air, insulating oil, and insulating gas may be used as the insulating medium.

It is a perspective view showing the whole direct-current reactor composition of the present invention. It is sectional drawing which shows the principal part of the said DC reactor. It is a figure which shows the structure of the magnetic body core of the said DC reactor. It is a figure which compares and shows the case where the magnitude | size of the said DC reactor makes the height of the coil | winding equal to the conventional DC core reactor with a gap. It is a figure which shows the structure of the DC substation for electric railways which attaches the DC reactor of this invention, and load. It is a figure which shows the relationship between the electric current sent through the direct current | flow reactor of this embodiment, and an inductance. It is a figure which shows the suppression effect of the harmonic component of the rectification ripple of the direct current reactor of this embodiment compared with the conventional direct current reactor. It is a figure which shows the transient increase of the fault current which flows into the direct current reactor of this embodiment. It is a figure which compares and shows the magnitude | size of the loss of the direct current reactor of this embodiment, and the direct current reactor of the other conventional system. It is a figure which shows the relationship between the electric current sent through the conventional DC core reactor of a gap type iron core, and an inductance. It is a figure which shows the relationship between the electric current sent through the conventional air-core type DC reactor, and an inductance. It is a figure which shows the increase in the fault current in the conventional DC reactor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC reactor 2 (2A, 2B) Winding 3 Magnetic body core 10 Iron core block 11 Paramagnetic body block 20 DC substation 25 for electric railways 25 Rectifier

Claims (3)

  A DC reactor that is connected in series with the rectifier of a DC substation for electric railways and installed on the return line side, so that the inductance in the air-core state can be controlled so that the rise of the fault current when an accident occurs can be interrupted by the circuit breaker And a magnetic core inserted into the winding such that the inductance in a rated current region of 2000 A or more is reduced to a rectification ripple generated by rectification. A direct current reactor characterized by comprising:   A DC reactor connected in series with a rectifier of a DC substation for electric railways, having a winding and a magnetic core inserted into the winding, and having an inductance in a rated current region of 2000 A or more of 1.1 to A DC reactor characterized by being 1.3 mH and having an inductance in a current region in which the magnetic core is magnetically saturated being 0.5 to 0.7 mH. 3. The gap core core according to claim 1, wherein the magnetic core is a gap core core in which a plurality of core blocks made of a ferromagnetic material and a plurality of paramagnetic blocks interposed between the core blocks are alternately stacked. The described direct current reactor.

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