CN106816278B - A metal washer of a saturable reactor for a converter valve - Google Patents

Abstract

The present invention provides a kind of metal washer of saturable reactor for converter valve, which is the circular ring shape of opening, and washer is equipped with concentric cooling water channel, which uses the electric steel of high magnetic permeability.Metal washer provided by the invention is water cooling, and the heat of metal washer and saturable reactor is all taken away by the water, and is reduced the running temperature of iron core, is reduced the volume of converter valve module, maintain iron core high magnetic permeability and non-linear characteristic.

Description

A metal washer of a saturable reactor for a converter valve

technical field

The invention relates to the technical field of power electronics and direct current transmission, in particular to a metal washer of a saturable reactor for a converter valve.

Background technique

As a mature and reliable large-capacity, long-distance power transmission technology, HVDC has played an important role in the cross-regional networking projects in my country and even the world. In order to meet the needs of the rapid development of the national economy, my country has built a number of UHV DC transmission lines in recent years. The voltage level and transmission capacity of these DC transmission lines once reached the highest in the world, and their safe and reliable operation is directly related to my country's economy and society. of stability.

The converter valve is the core equipment of the DC transmission system, and the saturable reactor is the key component of the HVDC converter valve. The protective effect on the protection thyristor is reflected in:

①In the initial stage of thyristor turn-on, the saturable reactor can provide enough resistance and inductance to suppress the excessive growth of gate current;

②Under the action of lightning and steep wave overvoltage, most of the peak voltage is borne by it;

③In the vicinity of the first valley current, it provides a small enough damping resistance to avoid the sudden cut-off of the thyristor turn-on current.

After the thyristor is turned on, the iron core works in a fully saturated state. At this time, its inductance and resistance are extremely small, which will not increase the active and reactive power losses of the converter valve system. This is how a saturable reactor works.

The size of the existing saturable reactor is large, resulting in a large length and width of the converter valve, so the miniaturized design of the saturable reactor has become a research hotspot. In order to reduce the volume of the saturable reactor, the most direct way is to reduce the number of iron core pairs. However, when the heating power is constant, the heating value of the single iron core will increase exponentially, causing the saturable reactor to overheat. Long-term overheating of electrical components will accelerate their aging and reduce their service life. In severe cases, the components will fail, and even major accidents such as explosion and fire will occur. Therefore, it is necessary to develop a saturable reactor washer. The maximum operating temperature of the iron core is less than the allowable value.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art that the saturable reactor occupies a large area, the length and width of the converter valve are large, the operating temperature of the iron core of the saturable reactor rises, and the service life of the material is affected, etc., the present invention provides a converter valve for Metal washers for saturable reactors.

A metal washer of a saturable reactor for a converter valve is improved in that the metal washer is an open circular ring; the metal washer is provided with a concentric cooling water channel.

Further, the cross-section of the metal washer is rectangular, and the cross-section of the cooling water channel is circular; the opening arc of the metal washer is 0-90 degrees.

Further, the metal washer is made of a silicon steel sheet with a relative magnetic permeability of 4000.

Further, the iron core of the saturable reactor is formed by superimposing elliptical track-shaped laminations; the metal washers are symmetrically arranged on the track.

Further, the metal washer is a metal washer with high magnetic permeability, and the magnetic flux density B _m it withstands is equal to the magnetic flux density B _Fe in the silicon steel sheet, and the eddy current loss per unit volume of the metal washer is proportional to the electrical conductivity and Lamination thickness squared.

Further, the eddy current loss per unit volume of the metal washer is represented by the following formula

In the formula, γ is the electrical conductivity; δ is the thickness of the single silicon steel sheet; ω is the frequency of the harmonic current, and B is the average magnetic flux density on the thickness of the single silicon steel sheet.

Further, the length of the cross section of the metal washer is represented by Δ _=NL δ, where _NL is the number of laminations of a single iron core, and δ is the lamination thickness of the silicon steel sheet.

Further, the eddy current loss per unit volume of the metal washer is represented by the following formula:

The eddy current loss per unit volume of silicon steel sheet is expressed by the following formula:

In the above two formulas, γ is the electrical conductivity; δ is the thickness of the single piece of silicon steel; ω is the frequency of the harmonic current, B is the average magnetic flux density on the thickness of the single piece of silicon steel, and _NL is the thickness of the single piece of iron core. number of laminations;

It can be seen that the eddy current loss per unit volume of the metal washer is about the same as that of the silicon steel sheet per unit volume. times.

Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

1. In the technical solution provided by the present invention, the metal gasket greatly reduces the overall size of the saturable reactor and reduces the volume of the converter valve module;

2. In the technical solution provided by the present invention, the metal gasket adopts silicon steel sheet with almost zero calorific value, which reduces the difficulty of heat exchange design of the saturable reactor;

3. The cooling water channel contained in the middle of the metal washer provided by the present invention takes all the heat of the metal washer and the heat of the saturated reactor (including copper loss and iron loss) away, reducing the heat dissipation in the air and greatly reducing the iron loss. Therefore, the operating load of the air-conditioning system of the converter valve hall is greatly reduced, the high temperature resistance level of the insulating material is reduced, and the difficulty of insulation design is reduced;

4. In the technical solution provided by the present invention, the metal gasket adopts an open circular design, which not only reduces the resistance of cooling water, but also facilitates the fixing of the gasket; the introduction of the metal gasket not only achieves a good heat dissipation effect, but also maintains The high permeability and nonlinear characteristics of the iron core are obtained.

Description of drawings

Figure 1 is a structural diagram of a metal washer

Figure 2 is a sectional view of the metal washer

Figure 3 is a structural diagram of a monolithic iron core

Figure 4 is a schematic diagram of the structure of the saturable reactor

Among them, 1-primary coil, 2-iron core (laminate), 3-metal washer, 4-incoming wire end, 5-outgoing wire end, 6-cooling water channel

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

As shown in FIG. 1 , the metal washer is an open circular ring with an opening arc of 0-90 degrees; the washer is provided with a concentric cooling water channel 6 . As shown in the cross-sectional view of the metal washer in FIG. 2 , the cross-section of the metal washer 3 is a rectangle with a concentric ring, and the concentric ring is the cooling water channel 6 .

The iron core of the saturable reactor is formed by superimposing oval racetrack-type laminations, with three layers of primary coils passing through the middle. As shown in Figure 4, the primary coils enter from the incoming end 4 and go out from the outgoing end 5. Metal washers Symmetrically arranged on the elliptical runway of the saturable reactor.

In order to make full use of the high magnetic permeability of the iron core, it is required that the magnetic permeability of the metal washer itself is as large as possible. Otherwise, due to the influence of the metal magnetic resistance, the magnetization curve of the saturable reactor will be very flat, and it is difficult to obtain a large inductance. and obvious nonlinear inductance characteristics. In order to meet the requirement of high magnetic permeability of the metal washer itself, the metal washer of the present invention is made of electric furnace steel with a relative magnetic permeability of 4000.

The eddy current loss per unit volume of the metal gasket in the present invention is represented by the following formula

In the formula, γ is the electrical conductivity; δ is the thickness of the single silicon steel sheet; ω is the frequency of the harmonic current, and B is the average magnetic flux density on the thickness of the single silicon steel sheet.

It can be seen from formula (1) that the eddy current loss per unit volume of the metal conductor is proportional to the square of the frequency ω and the thickness δ of the silicon steel sheet, and is also proportional to the electrical conductivity γ and the average magnetic flux density B.

In the saturable reactor, the magnetic permeability of the metal washer is very high, and the magnetic flux density B _m borne by the metal washer 3 is equal to the magnetic flux density B _Fe in the silicon steel sheet. In the above case, the eddy current loss per unit volume of the metal gasket is proportional to the conductivity of the material itself and the square of the thickness of the lamination. The metal washer is located in the center of the iron core of the saturable reactor. Due to the large eddy current area of the metal washer, most of the heat of the saturable reactor will be transferred to the metal washer, reducing the temperature of the iron core.

Generally, the lamination thickness δ of the silicon steel sheet is extremely small, and the thickness of the metal washer is Δ _=NL δ, where _NL is the number of laminations of a single iron core.

The eddy current loss per unit volume of the silicon steel sheet in this embodiment is

The eddy current loss per unit volume of the metal gasket is

In the above two formulas, γ is the electrical conductivity; δ is the thickness of the single piece of silicon steel; ω is the frequency of the harmonic current, B is the average magnetic flux density on the thickness of the single piece of silicon steel, and _NL is the thickness of the single piece of iron core. number of laminations;

It can be seen that the eddy current loss per unit volume of the metal washer is about the same as that of the silicon steel sheet per unit volume. times.

When the thickness of the silicon steel lamination is 0.10mm, the number of iron core laminations is 300, and the thickness of the metal gasket is 20mm, the theoretical calculation shows that the thermal power loss of the metal gasket is about 3000 times that of the silicon steel sheet. In other words, all the thermal power loss of the saturable reactor is concentrated in the metal washer, and the loss of the silicon steel sheet is approximately zero. Because there is a cooling water channel in the middle of the metal gasket, the water in the water channel takes away most of the heat generated by the metal gasket and the saturable reactor, which reduces the high temperature resistance level of the insulating material and reduces the operating load of the air conditioning system in the converter valve hall.

In the embodiment, the metal gasket of the saturable reactor for the converter valve is water-cooled, which solves the problem of its own heat dissipation. When the logarithm of the iron core is reduced, it is ensured that the maximum operating temperature of the iron core is less than the allowable value, reducing the The volume of the saturable reactor converter valve module is reduced.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: The specific embodiment of the invention is modified or equivalently replaced, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be included in the scope of the claims of the present invention.

Claims (5)

1. a kind of metal washer of saturable reactor for converter valve, which is characterized in that the metal washer is the circular ring shape of opening；Institute Metal washer is stated equipped with concentric cooling water channel；

The section of metal washer is rectangle, and the section of cooling water channel is circle；The opening radian of the metal washer is 0-90 degree；

The metal washer is made of relative permeability of 4000 silicon steel sheet；

The iron core of the saturable reactor is formed by stacking by track type lamination；The metal washer symmetric transverse is set to institute It states on runway.

2. metal washer as described in claim 1, which is characterized in that the metal washer is the metal washer of high magnetic permeability, The magnetic flux density B of receiving_mEqual to the magnetic flux density B in silicon steel sheet_Fe, the unit volume eddy-current loss of the metal washer is proportional to material Expect itself conductivity and lamination thickness square.

3. metal washer as claimed in claim 2, which is characterized in that under the unit volume eddy-current loss of the metal washer is used Formula indicates

In formula, γ is conductivity；δ is the thickness of monolithic silicon steel sheet；ω is the frequency of harmonic current, and B is in monolithic silicon steel sheet thickness Average flux density on degree.

4. metal washer as described in claim 1, which is characterized in that the length of metal washer cross section Δ=N_Lδ expression, Wherein N_LFor the number of laminations of monolithic iron core, δ is the lamination thickness of silicon steel sheet.

5. metal washer as claimed in claim 4, which is characterized in that the eddy-current loss of the unit volume of the metal washer is used Following formula indicates:

The eddy-current loss of the unit volume of silicon steel sheet is indicated with following formula:

In above-mentioned two formula, γ is conductivity；δ is the thickness of monolithic silicon steel sheet；ω is the frequency of harmonic current, and B is in single piece of silicon Average flux density on steel plate thickness, N_LFor the number of laminations of monolithic iron core；

The eddy-current loss for knowing metal washer unit volume is about unit volume silicon steel sheetTimes.