A saturable reactor suitable for DC transmission system

Abstract

The present invention provides a saturated reactor suitable for a direct current transmission system, the reactor comprising an iron core, a coil and a water cooling system; the coil is connected in parallel with a variable resistor whose resistance is inversely proportional to the current passing through it, and the reactor body composed of the coil and the iron core is provided with a water cooling system. The present invention connects a resistor with a variable resistance in parallel to the iron core coil of a traditional reactor; and its resistance is inversely proportional to the current passing through it; when the thyristor connected in series with the reactor is turned on, since the current passing through the variable resistor is relatively small, its resistance is relatively large, which can provide sufficient damping to limit the excessive growth of the thyristor gate current; and after the thyristor is fully turned on, the current passing through the variable resistor increases, so its resistance decreases, the corresponding damping decreases rapidly, and the heat generated by it decreases; the on-state energy loss is reduced, and the heat dissipation of the reactor is improved.

Description

Technical Field

[0001] The invention relates to a reactor, in particular to a saturated reactor suitable for a direct current power transmission system. Background Art

[0002] Saturated reactors are key components of DC power transmission converters and play an important role in protecting thyristors. In the transient state of the converter valve, the conduction of the thyristor begins near the gate, and the conduction area takes a certain amount of time to gradually expand. Therefore, when the voltage between the anode and cathode of the thyristor has not reached the stable on-state voltage value, a considerable current flows through, and the resulting turn-on loss may cause device damage. In order to suppress di / dt and protect the thyristor, a saturated reactor is required. In addition, due to the presence of stray capacitance in the converter transformer, the capacitor and the inductor of the saturated reactor will oscillate in parallel. In extreme cases, the negative peak value of the oscillating current will be close to the positive peak value, so that the thyristor current is just turned on and then turned off at zero, causing device damage. Therefore, the saturated reactor must provide the necessary damping.

[0003] The usual design scheme of saturated reactors is to control the inherent hysteresis loss and eddy current loss of the iron core at a certain level, and use parasitic energy loss to consume oscillation energy and suppress oscillation amplitude. In the early stage of thyristor opening, the eddy current induced in the iron core of the saturated reactor flows inside the silicon steel sheet, providing a sufficiently large eddy current resistance to prevent the gate current of the thyristor connected in series with the reactor from increasing too fast. When the thyristor is gradually turned on, the induced current in the iron core gradually decreases, and the eddy current resistance also decreases accordingly. The damping of the saturated reactor is reduced, which will not cause excessive obstruction to the on-state current and prevent unnecessary energy loss. During the transient process of opening, the energy of electromagnetic oscillation is eventually converted into heat of the iron core, and then leaves the reactor through the water cooling system to ensure that the reactor will not be damaged due to overheating. However, in actual engineering applications, since the reactor carries a high voltage, it must be wrapped with an insulating layer on the outside for effective insulation. The existence of the insulating layer will seriously affect the effect of the water cooling system, so that the heat of the reactor cannot be dissipated in time, which may cause damage to the reactor. Summary of the invention

[0004] In view of the deficiencies in the prior art, the applicant has designed a saturated reactor suitable for a DC power transmission system; a resistor with a variable resistance is connected in parallel to the core coil of a traditional reactor; and its resistance value is inversely proportional to the current passing through it; when the thyristor connected in series with the reactor is turned on, since the current passing through the variable resistor is relatively small, its resistance value is relatively large, which can provide sufficient damping and limit the excessive growth of the thyristor gate current; and after the thyristor is fully turned on, the current passing through the variable resistor increases, so its resistance value decreases, the corresponding damping decreases rapidly, and the heat generated by it is reduced; the on-state energy loss is reduced, and the heat dissipation of the reactor is improved, which is of great significance in engineering practice.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a saturated reactor suitable for a direct current transmission system, the reactor comprising an iron core, a coil and a water cooling system; the coil is connected in parallel with a variable resistor whose resistance is inversely proportional to the current passing through the coil, and the reactor body composed of the coil and the iron core is provided with a water cooling system.

[0007] Preferably, the variable resistor comprises: a spiral resistor made of a force-sensitive resistor material; the resistance value of the force-sensitive resistor material is inversely proportional to the force it is subjected to.

[0008] Preferably, the cross-section of the force-sensitive resistor material is a parallelogram.

[0009] Preferably, the ratio of the long side to the short side of the parallelogram is 8-15:1.

[0010] Preferably, the long side of the parallelogram is 0.5 to 1 cm.

[0011] Preferably, the long sides of the parallelogram of each cross section of the force-sensitive resistor material are respectively perpendicular to the axis of the spiral resistor.

[0012] Preferably, the iron core comprises a silicon steel sheet assembly formed by stacking silicon steel sheets.

[0013] Preferably, the thickness of the silicon steel sheet is 0.2 mm to 0.5 mm.

[0014] Preferably, the distance between the variable resistor and the reactor body consisting of the coil and the iron core is 0.5-1 m.

[0015] Compared with the closest prior art, the beneficial effects of the present invention are:

[0016] 1. The technical solution provided by the present invention is to connect a resistor with a variable resistance in parallel to the core coil of a traditional reactor; and its resistance value is inversely proportional to the current passing through it; when the thyristor connected in series with the reactor is turned on, since the current passing through the variable resistor is relatively small, its resistance value is relatively large, which can provide sufficient damping and limit the excessive growth of the thyristor gate current; and after the thyristor is fully turned on, the current passing through the variable resistor increases, so its resistance value decreases, the corresponding damping decreases rapidly, and the heat generated by it is reduced; the on-state energy loss is reduced, and the heat dissipation of the reactor is improved, which is of great significance in engineering practice.

[0017] 2. The technical solution provided by the present invention realizes the characteristic that the resistance value is inversely proportional to the current in a spiral resistor made of a force-sensitive resistor whose resistance value is inversely proportional to the force: when the current passing through the resistor is small, the gravitational force between adjacent circuits of the spiral resistor is small, that is, the force is small and its resistance is large; when the current passing through the resistor is large, the gravitational force between adjacent circuits of the spiral resistor is large, and the distance between them is reduced under the action of the gravitational force, and the gravitational force between them is further increased, that is, the force is large and its resistance is small.

[0018] 3. In the technical solution provided by the present invention, the iron core is made of stacked silicon steel sheets with small thickness, which limits the internal eddy current, significantly reduces the heat generated by the iron core, and further improves the heat dissipation of the reactor.

[0019] 4. In the technical solution provided by the present invention, the cross-section of the force-sensitive resistor material of the variable resistor is a parallelogram, and the ratio between its long side and short side is large, that is, the force-sensitive resistor material has a thin sheet structure, so the heat dissipation area is large, which further improves the heat dissipation of the reactor.

[0020] 5. In the technical solution provided by the present invention, the parallelograms of the cross sections of the force-sensitive resistor material are respectively perpendicular to the axis of the spiral resistor, that is, the surfaces of the thin sheet-like force-sensitive resistor material are parallel to each other, and the relative area of ​​adjacent circuits of the spiral resistor reaches a maximum. When power is turned on, the attraction between adjacent circuits can reach a maximum, thereby increasing the sensitivity of the variable resistor's resistance value to changes with the current passing through it.

[0021] 6. In the technical solution provided by the present invention, the variable resistor and the reactor body composed of the coil and the iron core are independent of each other, which reduces the influence between them, makes it easier to dissipate the heat, and further improves the heat dissipation of the reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings:

[0023] Figure 1 : A schematic diagram of the structure of the reactor provided by the present invention;

[0024] Figure 2 : A schematic structural diagram of a reactor body provided by the present invention;

[0025] Figure 3 : The structure diagram of the spiral force-sensitive resistor provided by the present invention;

[0026] Figure numerals: 1-iron core, 2-coil, 3-reactor body, 4-reactor body water cooling subsystem, 5-variable resistor, 6-force sensitive resistor material. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0028] The present invention provides a saturated reactor suitable for a direct current transmission system, the reactor comprising an iron core 1, a coil 2 and a water cooling system; the coil 2 is connected in parallel with a variable resistor 5 whose resistance value is inversely proportional to the current passing through the coil 2, and a reactor body 3 composed of the coil 2 and the iron core 1 is provided with a water cooling system 4.

[0029] The variable resistor 5 includes: a spiral resistor made of a force-sensitive resistor material 6; the resistance value of the force-sensitive resistor material 6 is inversely proportional to the force it is subjected to.

[0030] The cross section of the force-sensitive resistor material 6 is a parallelogram.

[0031] The ratio of the long side to the short side of the parallelogram is 8 to 15:1.

[0032] The long side of the parallelogram is 0.5 to 1 cm.

[0033] The long sides of the parallelograms of the cross sections of the force-sensitive resistor material 6 are respectively perpendicular to the axis of the spiral resistor.

[0034] The iron core 1 includes a silicon steel sheet assembly formed by stacking silicon steel sheets.

[0035] The thickness of the silicon steel sheet is 0.2 mm to 0.5 mm.

[0036] The distance between the variable resistor 5 and the reactor body 3 composed of the coil 2 and the iron core 1 is 0.5-1 m; the variable resistor 3 and the reactor body 3 composed of the coil 2 and the iron core 1 are independent of each other.

[0037] The variable resistor 5 does not need to be provided with a water cooling system.

[0038] Finally, it should be noted that the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present application.

Claims

1. A saturated reactor suitable for a DC power transmission system, the reactor comprising an iron core, a coil and a water cooling system; characterized in that: The coil is connected in parallel with a variable resistor whose resistance value is inversely proportional to the current passing through it, and the reactor body composed of the coil and the iron core is provided with a water cooling system; The variable resistor comprises: a spiral resistor made of a force-sensitive resistor material; the resistance value of the force-sensitive resistor material is inversely proportional to the force it is subjected to; The cross section of the force-sensitive resistor material is a parallelogram; The long sides of the parallelograms of the cross sections of the force-sensitive resistor material are respectively perpendicular to the axis of the spiral resistor; The reactor is connected in series with the thyristor; The iron core includes a silicon steel sheet assembly formed by stacking silicon steel sheets.

2. A saturable reactor suitable for a DC power transmission system according to claim 1, characterized in that: The ratio of the long side to the short side of the parallelogram is 8-15:

1.

3. The saturable reactor suitable for a DC power transmission system according to claim 1, characterized in that: The long side of the parallelogram is 0.5-1 cm.

4. The saturable reactor suitable for a DC power transmission system according to claim 1, characterized in that: The thickness of the silicon steel sheet is 0.2 mm to 0.5 mm.

5. The saturable reactor suitable for a DC power transmission system according to claim 1, characterized in that: The distance between the variable resistor and the reactor body composed of the coil and the iron core is 0.5-1m.

6. A saturable reactor suitable for a DC power transmission system according to claim 1, characterized in that: The variable resistor does not need to be provided with a water cooling system.

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