CN209823437U - Flexible direct current transmission system, electrical system thereof and diode valve string - Google Patents
Flexible direct current transmission system, electrical system thereof and diode valve string Download PDFInfo
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- CN209823437U CN209823437U CN201921005689.1U CN201921005689U CN209823437U CN 209823437 U CN209823437 U CN 209823437U CN 201921005689 U CN201921005689 U CN 201921005689U CN 209823437 U CN209823437 U CN 209823437U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
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- Y02E10/76—Power conversion electric or electronic aspects
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The utility model discloses a flexible direct current transmission system and electrical system, diode valve cluster thereof. An electrical system for a flexible direct current transmission system comprising: the direct current wind generating set comprises a direct current wind generating set, a first direct current smoothing reactor, a second direct current smoothing reactor, an MMC converter valve and a diode valve string; the direct current wind generating set is connected with one end of a first direct current smoothing reactor through a positive direct current bus, the other end of the first direct current smoothing reactor is connected with an anode of a first diode valve string, and a cathode of the first diode valve string is connected with a positive direct current input end of the MMC converter valve; the direct current wind generating set is connected with one end of a second direct current smoothing reactor through a negative direct current bus, the other end of the second direct current smoothing reactor is connected with a cathode of a second diode valve string, and an anode of the second diode valve string is connected with a negative direct current input end of the MMC converter valve. Adopt the utility model discloses scheme can carry out short-circuit protection to flexible direct current transmission system.
Description
Technical Field
The utility model relates to an electric power tech field especially relates to a flexible direct current transmission system and electrical system, diode valve cluster thereof.
Background
At present, environmental pollution and energy shortage become a century-oriented problem in modern civilization society. In order to cope with this problem, various new energy sources which are pollution-free and renewable are continuously sought. Among them, wind energy has attracted attention as a clean and pollution-free renewable energy source, and wind power generation using wind energy as an energy source is increasingly receiving attention from countries all over the world.
A plurality of wind driven generators in the wind generating set convert wind energy into electric energy, the generated electric energy is converged to the direct current transmission system, and the converged electric energy is transmitted to a power grid through the direct current transmission system. The existing direct current transmission system comprises a positive direct current transmission line, a negative direct current transmission line and a current converter. The converter converts direct current on the direct current transmission system into alternating current, and then the alternating current is incorporated into a power grid. However, existing dc transmission systems lack the ability to short-circuit themselves.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a flexible direct current transmission system and electrical system, diode valve cluster thereof can carry out short-circuit protection to flexible direct current transmission system.
According to the utility model discloses an aspect provides a flexible direct current transmission system's electrical system, includes: the direct current wind generating set comprises a direct current wind generating set, a first direct current smoothing reactor, a second direct current smoothing reactor, an MMC converter valve and a diode valve string;
wherein the diode valve string comprises a first diode valve string and a second diode valve string,
the direct current wind generating set is connected with one end of a first direct current smoothing reactor through a positive direct current bus, the other end of the first direct current smoothing reactor is connected with an anode of a first diode valve string, and a cathode of the first diode valve string is connected with a positive direct current input end of the MMC converter valve;
the direct current wind generating set is connected with one end of a second direct current smoothing reactor through a negative direct current bus, the other end of the second direct current smoothing reactor is connected with a cathode of a second diode valve string, and an anode of the second diode valve string is connected with a negative direct current input end of the MMC converter valve;
the alternating current output end of the MMC converter valve is connected with a power grid through an alternating current transformer;
each diode valve string comprises M diode valve strings connected in series in the same direction, each diode valve string comprises N diodes connected in series in the same direction, and M, N are positive integers.
According to the utility model discloses an on the other hand provides a flexible direct current transmission system, include: the embodiment of the utility model provides an electric system of flexible direct current transmission system, for the water cooling system of electric system heat dissipation;
the MMC converter valve in the electric system comprises three-phase converter power bridge arms which are connected in parallel, each phase converter power bridge arm comprises an upper bridge arm and a lower bridge arm, and each phase upper bridge arm and each phase lower bridge arm respectively comprise one or more than two cascaded SM submodules;
the first diode valve string and the second diode valve string respectively comprise three diode valve strings, the three diode valve strings in the first diode valve string are respectively arranged in one-to-one correspondence with the upper bridge arms of the three-phase commutation power bridge arms, and the three diode valve strings in the second diode valve string are respectively arranged in one-to-one correspondence with the lower bridge arms of the three-phase commutation power bridge arms;
wherein, water cooling system includes: the system comprises a water supply device, an upper bridge arm water-cooling main pipeline, a lower bridge arm water-cooling main pipeline, a water-cooling pipeline of a three-phase upper bridge arm, a water-cooling pipeline of a three-phase lower bridge arm, a heat dissipation pipeline of an SM submodule and a heat dissipation pipeline of a diode valve string, wherein the water supply device is connected with the upper bridge arm water-cooling main pipeline;
the first end of the upper bridge arm water-cooling main pipeline and the first end of the lower bridge arm water-cooling main pipeline are both connected with a water supply device, the second end of the upper bridge arm water-cooling main pipeline is respectively connected with the first ends of the water-cooling pipelines of the three-phase upper bridge arms which are connected in parallel, and the second end of the lower bridge arm water-cooling main pipeline is respectively connected with the first ends of the water-cooling pipelines of the three-phase lower bridge arms which are connected in parallel;
the second end of the water-cooling pipeline of each phase upper bridge arm is respectively connected with each SM submodule through the heat dissipation pipeline of each SM submodule of each phase upper bridge arm and connected with the corresponding diode pipe valve string through the heat dissipation pipeline of the corresponding diode pipe valve string;
and the second end of the water-cooling pipeline of each phase of lower bridge arm is respectively connected with each SM submodule through the heat dissipation pipeline of each SM submodule of each phase of lower bridge arm and connected with the corresponding diode pipe valve string through the heat dissipation pipeline of the corresponding diode pipe valve string.
According to another aspect of the embodiments of the present invention, there is provided a diode valve string, including: m diode valve strings connected in series in the same direction, and an overvoltage protector arranged in parallel with the M diode valve strings connected in series in the same direction;
each diode pipe valve string comprises N diodes which are connected in series in the same direction, K water cooling plates, a first metal compression joint plate, an insulating support plate, a second metal compression joint plate and a compression joint fixing part;
in the arrangement direction of the N diodes connected in series in the same direction, the K water cooling plates and the N diodes are alternately arranged and are connected in an equipotential manner, and the first water cooling plate and the K water cooling plate are respectively arranged at the head end and the tail end;
the first metal compression joint plate is connected with one end of the first water cooling plate in an equipotential manner, and the other end of the first water cooling plate is connected with the anode of the first diode in an equipotential manner;
one end of the insulating support plate is connected with the other end of the Kth water cooling plate, and the other end of the insulating support plate is connected with the second metal compression joint plate; one end of the Kth water-cooling plate is connected with the cathode of the Nth diode in an equipotential manner;
one end of the compression joint fixing part is connected with the first metal compression joint plate, the other end of the compression joint fixing part is connected with the second metal compression joint plate, and the water cooling plate and the diode are fixed through compression joint among the first metal compression joint plate, the second metal compression joint plate and the compression joint fixing part;
the overvoltage protector comprises a first electrical interface and a second electrical interface, the first electrical interface is connected with an anode in a first diode valve string, the second electrical interface is connected with a cathode in an Mth diode valve string, and M, N and K are positive integers.
According to the electric system and the flexible direct current transmission system of the flexible direct current transmission system provided by the embodiment of the utility model, a first diode valve string is arranged between the direct current wind generating set and the positive direct current input end of the MMC converter valve, and the anode of the first diode valve string is connected with the direct current wind generating set through a first direct current smoothing reactor and a positive direct current bus; and the cathode of the first diode valve string is connected with the positive direct-current input end of the MMC converter valve. And a second diode valve string is arranged between the direct current wind generating set and the negative direct current input end of the MMC converter valve, the anode of the second diode valve string is connected with the negative direct current input end of the MMC converter valve, and the cathode of the second diode valve string is connected with the direct current wind generating set through a second direct current smoothing reactor and a negative direct current bus. By arranging the two diode valve strings, when an electric system of the flexible direct current transmission system works normally, direct current can be allowed to be transmitted to the MMC converter valve normally, and is transmitted to an alternating current power grid after being inverted and boosted by the MMC converter valve and the alternating current transformer. When the electric system of the direct current transmission system generates reverse current due to short-circuit fault, the reverse current can be blocked reversely. Therefore, short-circuit protection can be performed on the direct current transmission system.
Drawings
The present invention may be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings, in which like or similar reference characters identify like or similar features.
Fig. 1 shows a schematic structural diagram of an electrical system of a flexible dc transmission system in the prior art;
fig. 2 is a schematic structural diagram illustrating an electrical system of a flexible dc transmission system according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a diode valve string according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another diode valve string provided in an embodiment of the present invention;
fig. 5 shows a schematic structural diagram of a flexible dc transmission system provided in an embodiment of the present invention;
fig. 6 is a schematic structural composition diagram of a diode valve string according to an embodiment of the present invention;
fig. 7 shows a detailed schematic diagram of a physical crimping structure of an exemplary diode valve string provided in an embodiment of the present invention;
fig. 8 shows a schematic structural diagram of a heat dissipation channel of a diode valve string according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 shows a schematic structural diagram of an electrical system of a flexible dc transmission system in the prior art. As shown in fig. 1, an electrical system 10A of the flexible dc transmission system includes: the direct current wind generating set 11, direct current circuit breakers 13A and 13B, direct current smoothing reactors 14A and 14B, and an MMC Converter valve 15(Modular Multilevel Converter, MMC).
For the electrical system 10A of the flexible dc transmission system, under normal conditions, the dc output by the dc wind generating set 11 is transmitted to the MMC converter valve 15 through the dc bus, the dc breaker, and the dc smoothing reactor, and then is inverted and boosted through the MMC converter valve 15 and the ac transformer 16, and then is transmitted to the ac power grid 17.
When a dc short-circuit fault occurs in the electrical system 10A of the flexible dc transmission system, the dc breaker 13 is turned off in time as shown by a dotted arrow in fig. 1 to block the return path of the short-circuit current, however, since the dc breaker is an electronic device based on an Insulated Gate Bipolar Transistor (IGBT), the dc breaker is often accompanied by problems of high cost, complex control, high fault rate, and the like.
Therefore, fig. 2 shows a schematic structural diagram of an electrical system of a flexible dc transmission system according to an embodiment of the present invention. As shown in fig. 2, an electrical system 10B of the flexible dc transmission system provided in the embodiment of the present invention includes: the direct current wind generating set comprises a direct current wind generating set 11, a first direct current smoothing reactor 14A, a second direct current smoothing reactor 14B, a diode valve string 19 and an MMC converter valve 15. Wherein the diode valve string 19 comprises a first diode valve string 19A and a second diode valve string 19B.
In an electrical system 10B of the flexible dc transmission system, a dc wind generating set 11 is connected to one end of a first dc smoothing reactor 14A through a positive dc bus 12, the other end of the first dc smoothing reactor 14A is connected to an anode of a first diode valve string 19A, and a cathode of the first diode valve string is connected to a positive dc input end of an MMC converter valve 15.
The direct current wind generating set 11 is connected with one end of a second direct current smoothing reactor 14B through a negative direct current bus 18, the other end of the second direct current smoothing reactor 14B is connected with a cathode of a second diode valve string 19B, and an anode of the second diode valve string 19B is connected with a negative direct current input end of the MMC converter valve 15.
The MMC converter valve 15 is provided with a positive dc input terminal, a negative dc input terminal, and an ac output terminal. Wherein, the ac output terminal of the MMC converter valve 15 is connected to an ac power grid 17 through an ac transformer 16.
In the present embodiment, the first dc smoothing reactor 14A and the second dc smoothing reactor 14B can suppress harmonic components in the electric system of the dc transmission system, thereby improving the power quality.
In the present embodiment, for the electrical system 10B of the flexible dc transmission system, under normal conditions, the dc output by the dc wind generating set 11 is transmitted to the MMC converter valve 15 through the dc bus, the dc smoothing reactor, and the diode valve string, and then is inverted and boosted through the MMC converter valve 15 and the ac transformer 16, and then transmitted to the ac power grid 17.
If a reverse backflow short-circuit current is generated in the electrical system 10B of the flexible direct-current transmission system due to a direct-current short-circuit fault, the diode valve string 19 can reversely block a backflow path of the short-circuit current, perform short-circuit protection on the electrical system 10B of the flexible direct-current transmission system, and perform safety protection on the MMC converter valve 15.
It should be noted that the embodiment of the utility model provides an in the direct current short circuit fault include direct current wind generating set ground connection/short circuit, anodal direct current transmission line ground connection, negative pole direct current transmission line ground connection, anodal direct current transmission line and negative pole direct current transmission line short circuit etc. can produce the multiple direct current short circuit fault of backward flow short circuit current, do not limit to this.
According to the electric system of the flexible direct current transmission system provided by the embodiment of the utility model, a first diode valve string is arranged between the direct current wind generating set and the positive direct current input end of the MMC converter valve, and the anode of the first diode valve string is connected with the direct current wind generating set through a first direct current smoothing reactor and a positive direct current bus; and the cathode of the first diode valve string is connected with the positive direct-current input end of the MMC converter valve. And a second diode valve string is arranged between the direct current wind generating set and the negative direct current input end of the MMC converter valve, the anode of the second diode valve string is connected with the negative direct current input end of the MMC converter valve, and the cathode of the second diode valve string is connected with the direct current wind generating set through a second direct current smoothing reactor and a negative direct current bus. By arranging the two diode valve strings, when an electrical system of the direct current transmission system works normally, direct current can be allowed to be transmitted to the MMC converter valve normally, and is transmitted to an alternating current power grid after being inverted and boosted by the MMC converter valve and the alternating current transformer. When the electric system of the flexible direct current transmission system generates reverse current due to short-circuit fault, the reverse current can be blocked reversely. Therefore, short-circuit protection can be performed on the direct current transmission system.
In addition, compared with the direct current circuit breaker of the electrical system 10A of the flexible direct current transmission system in the prior art, the diode valve string in the electrical system 10B of the flexible direct current transmission system effectively solves the problems of high cost, complex control and high failure rate of the direct current circuit breaker while giving consideration to short-circuit protection for the electrical system 10B of the flexible direct current transmission system and the MMC converter valve 15, and enhances the economy of the electrical system of the flexible direct current transmission system.
Fig. 3 shows a schematic structural diagram of a diode valve string according to an embodiment of the present invention. As shown in fig. 3, the diode valve string 19 includes M diode valve strings 191 connected in series in the same direction. Each diode string 191 includes N diodes connected in series in the same direction, D respectively1To DN. Wherein M, N are all positive integers.
In each diode string 191, N diodes D1To DNAre sequentially connected in series in the same direction in an anode-cathode mode. In particular, the first diode D1Cathode of the first diode D is connected with a second diode D2… …, the cathode of the N-1 th diode is connected with the Nth diode DNOf (2) an anode. First diode D1As the anode of the diode valve string 191, the Nth diode DNAs the cathode of the diode valve string 191.
Within the diode valve string 19, M diode valve strings 191 are serially connected in series in an anode-cathode manner. Specifically, the cathode of the first diode valve string 191 is connected to the anode, … …, of the second diode valve string 191, and the cathode of the M-1 th diode valve string 191 is connected to the anode of the M-th diode valve string 191. The anode of the first diode valve string 191 serves as the anode of the diode valve string 19, and the cathode of the mth diode valve string 191 serves as the cathode of the diode valve string 19.
Fig. 4 is a schematic structural diagram of another diode valve string provided in an embodiment of the present invention. Fig. 4 differs from fig. 3 in that the diode valve string 19 may further include overvoltage protectors 192 connected in parallel across the M diode valve strings connected in series in the same direction.
One end of the overvoltage protector 192 is connected to an anode of the first diode valve string 191, and the other end of the overvoltage protector 192 is connected to a cathode of the mth diode valve string 191.
In some embodiments, the overvoltage protector can be one arrester or a combination of multiple arresters. The plurality of arresters may be connected in parallel, in series, or in series-parallel, which is not limited herein.
In the present embodiment, the overvoltage protector 192 is provided, whereby overvoltage between both ends of the diode string can be suppressed. Particularly in a medium-voltage direct-current transmission system, the voltage value in the system can reach 1000V to 35 KV. Moreover, when the electrical system 10B of the flexible dc transmission system has a short-circuit fault, the voltage at the two ends of the diode valve string may even reach the sum of the port voltage of the MMC converter valve and the inductive voltage of the dc smoothing reactor. Therefore, by providing the overvoltage protector 192, the diode valve string can be excellently protected, the cost of the diode valve string is reduced on the premise of ensuring the normal use of the diode valve string in the electrical system 10B of the flexible direct current transmission system, and the reliability of the diode valve string is improved.
It should be further noted that, referring to fig. 3 and 4, whether to cross over the overvoltage protector 192 may be selected according to the specific implementation of the flexible dc transmission system. For example, whether the overvoltage protector 192 is connected or not may be determined according to at least one of parameters such as the number M of diode valve strings, the number N of diodes in the diode valve strings, a withstand voltage of the diodes, a port voltage of the MMC converter valve, and an inductance voltage of the dc smoothing reactor. Therefore, the structural design of the diode valve string is simple and flexible.
In some embodiments of the present invention, M is a positive integer. Preferably, for convenience and cost saving, M-3, i.e. the diode valve string in the electrical system 10B of the flexible dc transmission system described above, may be composed of three diode valve strings. It should be noted that, according to the requirement of the actual electrical system, the diode valve string may be composed of more than three diode valve strings, which is not limited herein. In some embodiments, the number, specifications, and manufacturing processes of the diodes included in each of the M diode valve strings are consistent without any difference.
In some embodiments of the present invention, N is a positive integer. Preferably, N is less than or equal to 10 in terms of insulation voltage resistance, manufacturing process reliability and the like.
The insulation and voltage resistance of the diode valve string are related to parameters such as the voltage resistance of the diode and the voltage value of the dc transmission system.
In some embodiments, the N diodes in each diode string are connected by crimping. Accordingly, the specific value of N may be selected in view of the reliability of the crimping.
It should be noted that, the embodiment of the present invention may also adopt other connection processes to connect the diode, which is not limited herein.
The embodiment of the utility model provides a flexible direct current transmission system, figure 5 shows the utility model provides a flexible direct current transmission system's schematic structure diagram is provided. As shown in fig. 5, the flexible dc transmission system includes: the electrical system 10B of the flexible dc transmission system and the water cooling system for cooling the electrical system 10B of the flexible dc transmission system.
Here, a part of the details of the electrical system 10B of the flexible dc transmission system are similar to the electrical system 10B of the flexible dc transmission system described above with reference to fig. 2 to 4, and are not repeated here.
With respect to the remaining details of the electrical system 10B of the flexible direct current transmission system, specifically, referring to fig. 5, the MMC converter valve 15 in the electrical system 10B of the flexible direct current transmission system includes three-phase converter power bridge arms connected in parallel, each of the three-phase converter power bridge arms includes an upper bridge arm and a lower bridge arm, and each of the upper bridge arm and the lower bridge arm includes one or more cascaded SM submodules 151.
The first diode valve string 19A and the second diode valve string 19B each include three diode valve strings 191. Three diode valve strings 191 in the first diode valve string 19A are respectively arranged in one-to-one correspondence with the upper bridge arms of the three-phase commutation power bridge arms. Three diode valve strings 191 in the second diode valve string 19B are respectively arranged in one-to-one correspondence with the lower bridge arms of the three-phase commutation power bridge arms.
Wherein, water cooling system includes: the system comprises a water supply device 41, an upper bridge arm water-cooling main pipeline 42, a lower bridge arm water-cooling main pipeline 43, a water-cooling pipeline of a three-phase upper bridge arm, a water-cooling pipeline of a three-phase lower bridge arm, a heat dissipation pipeline of an SM submodule and a heat dissipation pipeline of a diode valve string which are connected in parallel.
And a water supply device 41 configured to supply cold water to the upper arm water-cooling main pipe 42 and the lower arm water-cooling main pipe 43, and cool hot water that flows back to the water supply device 41 through the upper arm water-cooling main pipe 42 and the lower arm water-cooling main pipe 43.
Specifically, a first end of the upper arm water-cooling main pipe 42 is connected to the water supply device 41, and second ends of the upper arm water-cooling main pipe 42 are respectively connected to first ends of the water-cooling pipes of the three-phase upper arms connected in parallel. Wherein, the water-cooling pipeline of the parallelly connected three-phase upper bridge arm includes: the water-cooling pipeline 441 of the first-phase upper arm, the water-cooling pipeline 442 of the second-phase upper arm, and the water-cooling pipeline 443 of the third-phase upper arm. That is, the second end of the upper arm water-cooling main pipe 42 is connected to the first end of the water-cooling pipe 441 of the first-phase upper arm, the first end of the water-cooling pipe 442 of the second-phase upper arm, and the first end of the water-cooling pipe 443 of the third-phase upper arm, respectively.
A first end of the lower arm water-cooling main pipe 43 is connected to the water supply device 41. The second ends of the lower arm water-cooling main pipelines 43 are respectively connected with the first ends of the water-cooling pipelines of the three-phase lower arms connected in parallel. Wherein, the water-cooling pipeline of parallelly connected three-phase lower bridge arm includes: a water-cooled duct 451 of the first-phase lower arm, a water-cooled duct 452 of the second-phase lower arm, and a water-cooled duct 453 of the third-phase lower arm. That is, the second end of the lower arm water-cooling header pipe 43 is connected to the first end of the water-cooling pipe 451 of the first phase lower arm, the first end of the water-cooling pipe 452 of the second phase lower arm, and the first end of the water-cooling pipe 453 of the third phase lower arm, respectively.
The second end of the water-cooling pipeline of each upper bridge arm (i.e., the water-cooling pipeline 441 of the first upper bridge arm, the water-cooling pipeline 442 of the second upper bridge arm, and the water-cooling pipeline 443 of the third upper bridge arm) is connected to each SM submodule 151 through the heat-dissipation pipeline of each SM submodule of the upper bridge arm, and is connected to the corresponding diode valve string 191 through the heat-dissipation pipeline of the corresponding diode valve string. For example, the second end of the water-cooling pipe 441 of the first phase upper arm is connected to each SM submodule 151 through a heat dissipation pipe of each SM submodule of the first phase upper arm, and is connected to the diode valve string 191 corresponding to the first phase upper arm through a heat dissipation pipe of the diode valve string corresponding to the first phase upper arm. Similarly, the water-cooling pipes 442 and 443 of the second-phase upper arm and the first-phase upper arm are connected in the same manner, and are not described herein again.
The second end of the water-cooled pipe of each phase lower arm (the water-cooled pipe 451 of the first phase lower arm, the water-cooled pipe 452 of the second phase lower arm, the water-cooled pipe 453 of the third phase lower arm) is connected to each SM submodule 151 through the heat-dissipating pipe of each SM submodule of the phase lower arm, and is connected to the corresponding diode valve string 191 through the heat-dissipating pipe of the corresponding diode valve string. For example, the second end of the water cooling pipe 451 of the first phase lower arm is connected to each SM sub-module 151 through the heat dissipation pipe of each SM sub-module of the first phase lower arm, and is connected to the diode valve string 191 corresponding to the first phase lower arm through the heat dissipation pipe of the diode valve string corresponding to the first phase lower arm. Similarly, the water cooling pipes 452 and 453 of the second and third phase lower arms are connected to the water cooling pipe 451 of the first phase lower arm in the same manner, and thus, the detailed description thereof is omitted.
It should be noted that, in order to distinguish the connection relationship between the water-cooling pipeline and each device in the electrical system 10B of the flexible dc transmission system, the thicker line in fig. 5 represents the water-cooling pipeline, and the thinner line represents the electrical connection relationship between each device in the electrical system 10B of the flexible dc transmission system.
In this embodiment, by providing the water cooling system for the electrical system 10B of the flexible direct current transmission system, the electrical system 10B of the flexible direct current transmission system can be prevented from generating an over-temperature fault, and the safety of the electrical system 10B of the flexible direct current transmission system is improved.
In addition, because the dc circuit breaker in the flexible dc transmission system in the prior art is an IGBT-based power electronic device, which has a characteristic of large heat dissipation requirement, and the MMC converter valve also has a characteristic of large heat dissipation requirement, in practical applications, it is necessary to separately provide independent large-capacity water cooling systems to solve the heat dissipation problem of the flexible dc transmission system, and the water cooling system of the dc circuit breaker has a high cost, which accounts for 1/10 of the total cost of the dc circuit breaker, which is not favorable for the economy of the dc transmission system. And adopt the utility model discloses a diode valve string among the flexible direct current transmission system in the embodiment, the loss is less, and the heat dissipation demand is less. Meanwhile, the diode valve string and the MMC converter valve can share one water cooling system, so that the manufacturing cost of the water cooling system of the flexible direct current transmission system is reduced, and the economical efficiency of the flexible direct current transmission system is improved.
Further, each SM sub-module 151 (SM) of the electrical system 10B of the flexible direct current transmission system is provided with a water inlet and a water outlet. Cold water can enter the SM submodule 151 from a water inlet of the SM submodule 151, and flows out of the SM submodule 151 through a water outlet after the SM submodule 151 is cooled.
Each diode string 191 is provided with a water inlet and a water outlet. Cold water can flow into the diode valve string 191 from the water inlet of the diode valve string 191, cools the diode valve string 191, and then flows out of the diode valve string 191 through the water outlet.
In the embodiment of the present invention, fig. 5 only shows the simplified structure of the upper arm water-cooling main pipe 42 and the lower arm water-cooling main pipe 42. Specifically, the upper bridge arm water-cooling main pipeline 42 in the water-cooling system includes an upper bridge arm water inlet main pipeline and an upper bridge arm water return main pipeline. The lower bridge arm water-cooling main pipe 43 includes a lower bridge arm water inlet main pipe and a lower bridge arm water return main pipe.
For the water cooling pipes (e.g. 441, 442, 443) of the upper bridge arm of each phase, one side of the ellipses in fig. 5 represents a simplified structure of the water cooling pipes by a line segment, and the other side represents a detailed structure of the water cooling pipes by two straight lines. Specifically, the water cooling pipeline of each phase upper bridge arm comprises a water inlet pipeline of each phase upper bridge arm and a water return pipeline of each phase upper bridge arm. Wherein, in order to distinguish the water inlet pipe and the water return pipe, the water inlet pipe and the water return pipe are respectively represented by symbols a and b. Illustratively, the water-cooling pipe 441 of the first-phase upper arm includes a water inlet pipe 441a of the first-phase upper arm and a water return pipe 441b of the first-phase upper arm.
Similarly, the water-cooled pipes (e.g., 451, 452, 453) of each phase lower arm include a water inlet pipe of each phase lower arm and a water return pipe of each phase lower arm. Illustratively, the water-cooled pipe 451 of the first-phase lower arm includes a water inlet pipe 451a of the first-phase lower arm and a water return pipe 451b of the first-phase lower arm.
The heat dissipation pipe 46 of each SM sub-module includes a water inlet pipe 46a of each SM sub-module and a water return pipe 46b of each SM sub-module.
The heat dissipation pipe 47 of each diode valve string includes a water inlet pipe 47a of each diode valve string and a water return pipe 47b of each diode valve string.
Furthermore, although not shown in fig. 5, the first ends of the inlet conduits (e.g., 441a, 442a, 443a) of each phase upper leg are connected to the second ends of the upper leg inlet main conduits. The second end of the inlet pipe (e.g. 441a, 442a, 443a) of each phase upper bridge arm is connected with the inlet of each SM sub-module through the inlet pipe 46a of each SM sub-module of each phase upper bridge arm, respectively, and the second end of the inlet pipe (e.g. 441a, 442a, 443a) of each phase upper bridge arm is connected with the inlet of the corresponding diode pipe valve string through the inlet pipe 47a of the corresponding diode pipe valve string of the phase upper bridge arm. For example, the second end of the inlet pipe 441a of the first-phase upper arm is connected to the inlet port of each SM submodule through the inlet pipe 46a of each SM submodule of the first-phase upper arm, and is connected to the inlet port of the diode valve string through the inlet pipe 47a of the diode valve string corresponding to the first-phase upper arm.
The first end of the return pipe (441 b, 442b, 443b, for example) of each upper phase bridge arm is connected to the second end of the upper phase bridge arm return water main pipe. The second end of the water return pipe of each phase upper bridge arm is connected with the water outlet of each SM submodule through the water return pipe 46b of each SM submodule of each phase upper bridge arm, and is connected with the water outlet of the corresponding diode pipe valve string through the water return pipe 47b of the corresponding diode pipe valve string. Illustratively, the second end of the water return pipe 441b of the first-phase upper arm is connected to the water outlet of each SM sub-module through the water return pipe 46b of each SM sub-module of the first-phase upper arm, and is connected to the water outlet of the diode valve string through the water return pipe 47b of the diode valve string corresponding to the first-phase upper arm.
Furthermore, although not shown in fig. 5, the first end of the inlet conduit (e.g., 451a, 452a, 453a) of each phase lower arm is connected to the second end of the lower arm inlet header conduit. The second end of the inlet conduit (e.g. 451a, 452a, 453a) of each phase lower leg is connected to the inlet of each SM sub-module through the inlet conduit 46a of each SM sub-module of that phase lower leg and to the inlet of the diode valve string through the inlet conduit 47a of the corresponding diode valve string, respectively. Illustratively, the second end of the inlet pipe 451a of the first-phase lower arm is connected to the inlet of each SM sub-module through the inlet pipe 46a of each SM sub-module of the first-phase lower arm, and is connected to the inlet of the diode string through the inlet pipe 47a of the diode string corresponding to the first-phase lower arm.
The first end of the return pipe (e.g. 451b, 452b, 453b) of each phase lower leg is connected to the second end of the lower leg return water main. The second end of the return pipe (e.g., 451b, 452b, 453b) of each phase lower arm is connected to the return port of each SM submodule through the return pipe 46b of each SM submodule of each phase lower arm, and is connected to the water outlet of the corresponding diode valve string 191 through the return pipe 47b of the corresponding diode valve string. Illustratively, the second end of the return pipe 451b of the first-phase lower arm is connected to the water outlet of each SM sub-module through the return pipe 46b of each SM sub-module of the first-phase lower arm, and is connected to the water outlet of the diode valve string through the return pipe 47b of the diode valve string corresponding to the first-phase lower arm.
In addition, the first end of the upper bridge arm water inlet main pipeline and the first end of the upper bridge arm water return main pipeline, and the first end of the lower bridge arm water inlet main pipeline and the first end of the lower bridge arm water return main pipeline are connected with a water supply device.
Through sharing one set of water cooling system with diode valve cluster and MMC converter valve, not only can realize the high-efficient utilization to the water cooling system among the flexible direct current transmission system, can reduce the cost of the water cooling system of flexible direct current transmission system moreover, improved flexible direct current transmission system's economic nature.
The embodiment of the utility model provides a diode valve string, this diode valve string includes: m diode valve strings 191 connected in series in the same direction; and an overvoltage protector 192 (not shown) disposed in parallel with the series of M diode valves connected in series in the same direction. The overvoltage protector 192 includes a first electrical interface connected to the anode of the first diode valve string and a second electrical interface connected to the cathode of the mth diode valve string.
In order to more clearly describe the specific structure of the diode valve string, the present application will further describe the diode valve string 191. Referring to fig. 6 and 7, fig. 6 shows a schematic structural composition diagram of a diode valve string provided by the present invention. Fig. 7 shows a physical block diagram of the diode valve string of fig. 6.
As shown in fig. 6, the diode valve string includes: n diodes D connected in series in the same direction1To DN(ii) a K water-cooled plates 511 to 51K, a first metal crimping plate 52, an insulating support plate 53, a second metal crimping plate 54, a crimping fixing portion 55. Wherein N and K are positive integers. Specifically, the anode connection of the first diode valve string is connected to the anode of the first diode in the first diode valve string, and the cathode connection of the mth diode valve string is connected to the cathode of the nth diode in the mth diode valve string.
In the arrangement direction of the N diodes connected in series in the same direction, the K water-cooling plates and the N diodes are alternately arranged in equipotential connection, and the first water-cooling plate 511 and the K water-cooling plate 51K are respectively arranged at the head end and the tail end. Wherein, the other end of the first water-cooling plate 511 is connected with the first diode D1The anode of (1) is connected with the equipotential, and so on, one end of the Kth water-cooling plate 51K is connected with the Nth diode DNThe cathode of (a) is connected with an equipotential. Illustratively, K ═ N +1, i.e., one diode string includes N +1 cold water plates. Preferably, N is 10 or less. It should be noted that the equipotential connection here can refer to water coolingThe metal mounting surface of the plate is in contact with and pressed against the cathode or anode of the diode, and the same potential point is maintained.
The first metal crimping plate 52 is connected to one end of the first water cooling plate 511 in an equipotential manner. Illustratively, in the arrangement direction of the diodes, one end (e.g., the first metal surface) of the first water cooling plate 511 is in contact with and pressed against the first metal crimping plate 52, and the same potential point is maintained.
One end of the insulating support plate 53 is connected to the other end of the kth water-cooling plate 51K, and the other end of the insulating support plate 53 is connected to the second metal crimping plate 54. Illustratively, the other end (e.g., the second metal surface) of the kth water-cooling plate 51K is pressed in contact with one end (e.g., the first insulating surface) of the insulating support plate 53. The other end (e.g., the second insulating surface) of the insulating support plate 53 is pressed in contact with the second metal crimping plate 54. In the present embodiment, the insulating support plate 53 can maintain the potential of the second metal crimping plate 54 and the potential of the kth water cooling plate 51K with a sufficient creepage distance and electric clearance.
The crimp fixing portion 55 includes, for example, a metal screw 551 in fig. 6 and an insulating sleeve 552 fitted around the metal screw 551, one end of the crimp fixing portion 55 is connected to the first metal crimp plate 52, and the other end of the crimp fixing portion 55 is connected to the second metal crimp plate 54. The water cooling plate and the diode can be fixed by the pressure bonding between the first metal pressure bonding plate 52, the second metal pressure bonding plate 54, and the pressure bonding fixing portion 55. For example, as shown in fig. 7, the first metal crimping plate 52 and the second metal crimping plate 54 may each have a square or rectangular structure, and the water cooling plates and the diodes alternately arranged are located between the first metal crimping plate 52 and the second metal crimping plate 54 and form an approximately cylindrical shape. In view of the crimping strength, the fastening property, and the like, it is preferable that the crimping fixing part 55 includes four metal screws, which are respectively disposed at intervals along a circumferential direction formed by the water cooling plates and the diodes disposed alternately, and both ends of each metal screw respectively penetrate through holes or threaded holes formed in the first metal crimping plate 52 and the second metal crimping plate 54 to be fastened, and specifically, through holes or threaded holes capable of fixing the metal screws may be disposed at positions of four corners of the first metal crimping plate 52 and the second metal crimping plate 54 to be fastened by bolts. Of course, the form of the fixing of the metal screw is not limited.
In the present embodiment, by providing the insulating sleeve 552, the diode D can be held1Has enough creepage distance and electric clearance with the charged device connected in series on the diode valve string. Particularly, in the use scene of a medium-voltage direct-current power transmission system, the device and the screw are prevented from being too close to each other to discharge.
In some embodiments, with continued reference to fig. 6, to facilitate connection between the various diode valve strings or with other devices, the first water-cooled plate 511 in each diode valve string is provided with a first electrical interface e1, which may be the anode port of the diode valve string, e 1. The kth water-cooled plate 51K in the diode valve string is provided with a second electrical interface e2, which second electrical interface e2 may serve as a cathode port of the diode valve string.
In one embodiment, in a diode valve string, such as the first diode valve string 19A of the electrical system 10B of the flexible dc transmission system, the first electrical interface e1 in the first diode valve string is connected as an anode port of the first diode valve string 19A to a dc smoothing reactor. The second electrical interface e2 in the mth diode string serves as the cathode port of the first diode string 19A, connected to the MMC converter valve 15.
In another embodiment, in one diode valve string, for example the second diode valve string 19B of the electrical system 10B of the flexible dc transmission system, the first electrical interface e1 in the first diode valve string is connected to the MMC converter valve as the anode port of the second diode valve string 19B. The second electrical interface e2 in the mth diode string serves as the cathode port of the second diode string 19B, and is connected to the dc smoothing reactor.
Wherein inside the diode valve string, the second electrical interface e2 in the previous diode valve string of two adjacent diode valve strings is connected with the first electrical interface e1 in the next diode valve string to form a complete diode valve string.
In some embodiments, in order to achieve effective heat dissipation of the diode valve string, fig. 8 shows a schematic diagram of a heat dissipation channel in the structure of the diode valve string provided by an embodiment of the present invention. The water cooling plate in each diode pipe valve string comprises a water inlet interface and a water outlet interface. The water inlet port f1 of the first water cooling plate 511 is used as the water inlet of the diode valve string, and is connected to the water inlet pipe of the corresponding upper arm or the water inlet pipe of the corresponding lower arm through the water inlet pipe 47a of the diode valve string. The water outlet port f2 of the kth water-cooling plate 51K serves as the water outlet of the diode valve string. The outlet pipe 47b of the diode valve string is connected to the outlet pipe of the corresponding upper arm or the outlet pipe of the corresponding lower arm.
The water outlet port f2 of the previous water cooling plate in the two adjacent water cooling plates is connected with the water inlet port f1 of the next water cooling plate to form a heat dissipation channel inside the diode valve string. Specifically, the water outlet port f2 of the previous water cooling plate and the water inlet port f1 of the next water cooling plate can be connected through a pipeline H1.
In addition, a standardized heat dissipation flow channel is designed inside each water cooling plate. In the process of dissipating heat for the diode tube valve string, cold water enters the first water cooling plate 511 from the water inlet of the diode tube valve string, namely the water inlet port f1 of the first water cooling plate 511, flows out from the water outlet port f2 of the first water cooling plate 511 through the standardized heat dissipation flow channel in the first water cooling plate, enters the second water cooling plate 512 through the water inlet port f1 of the second water cooling plate 512, … …, and finally flows out from the water outlet port f2 of the last water cooling plate 51K, namely the water outlet port of the diode tube valve string.
In some embodiments, the value of N may also be determined according to the maximum operating temperature of the diode, and preferably, N is less than or equal to 10. Meanwhile, M is equal to 3 in order to satisfy the application of the practical flexible direct current transmission system, that is, the diode valve string includes three diode valve strings. Specifically, after the cold water cools the N diodes in sequence, it is ensured that the temperature of the last cooled diode is lower than the maximum operating temperature of the diode.
Above-mentioned diode valve string's design not only can be in the embodiment of the utility model provides an in flexible direct current transmission system realize the effective protection to the direct current short-circuit fault, simultaneously, can reduce the cost of using direct current circuit breaker and increasing extra water cooling system for whole flexible direct current transmission system, have higher economic value.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
Claims (10)
1. An electrical system of a flexible direct current transmission system, comprising: the direct current wind generating set comprises a direct current wind generating set, a first direct current smoothing reactor, a second direct current smoothing reactor, an MMC converter valve and a diode valve string;
wherein the diode valve string comprises a first diode valve string and a second diode valve string,
the direct current wind generating set is connected with one end of the first direct current smoothing reactor through a positive direct current bus, the other end of the first direct current smoothing reactor is connected with the anode of the first diode valve string, and the cathode of the first diode valve string is connected with the positive direct current input end of the MMC converter valve;
the direct current wind generating set is connected with one end of the second direct current smoothing reactor through a negative direct current bus, the other end of the second direct current smoothing reactor is connected with a cathode of the second diode valve string, and an anode of the second diode valve string is connected with a negative direct current input end of the MMC converter valve;
the alternating current output end of the MMC converter valve is connected with a power grid through an alternating current transformer;
each diode valve string comprises M diode valve strings connected in series in the same direction, each diode valve string comprises N diodes connected in series in the same direction, and M, N are positive integers.
2. The electrical system of a flexible DC transmission system according to claim 1,
each diode valve string further comprises overvoltage protectors connected in parallel to two ends of the M diode valve strings connected in series in the same direction.
3. The electrical system of a flexible direct current transmission system according to claim 1, wherein M is equal to 3.
4. The electrical system of a flexible direct current transmission system according to claim 1, wherein N is 10 or less.
5. A flexible DC transport system, comprising: an electrical system of a flexible direct current transmission system as claimed in any one of claims 1 to 4, and a water cooling system for dissipating heat from said electrical system;
the MMC converter valve in the electric system comprises three-phase converter power bridge arms which are connected in parallel, each phase converter power bridge arm comprises an upper bridge arm and a lower bridge arm, and each phase upper bridge arm and each phase lower bridge arm respectively comprise one or more than two cascaded SM submodules;
the first diode valve string and the second diode valve string respectively comprise three diode valve strings, the three diode valve strings in the first diode valve string are respectively arranged in one-to-one correspondence with the upper bridge arms of the three-phase commutation power bridge arms, and the three diode valve strings in the second diode valve string are respectively arranged in one-to-one correspondence with the lower bridge arms of the three-phase commutation power bridge arms;
wherein, the water cooling system includes: the system comprises a water supply device, an upper bridge arm water-cooling main pipeline, a lower bridge arm water-cooling main pipeline, a water-cooling pipeline of a three-phase upper bridge arm, a water-cooling pipeline of a three-phase lower bridge arm, a heat dissipation pipeline of an SM submodule and a heat dissipation pipeline of a diode valve string, wherein the water supply device is connected with the upper bridge arm water-cooling main pipeline;
the first end of the upper bridge arm water-cooling main pipeline and the first end of the lower bridge arm water-cooling main pipeline are both connected with the water supply device, the second end of the upper bridge arm water-cooling main pipeline is respectively connected with the first ends of the water-cooling pipelines of the three-phase upper bridge arms which are connected in parallel, and the second end of the lower bridge arm water-cooling main pipeline is respectively connected with the first ends of the water-cooling pipelines of the three-phase lower bridge arms which are connected in parallel;
the second end of the water-cooling pipeline of each phase upper bridge arm is respectively connected with each SM submodule through the heat dissipation pipeline of each SM submodule of each phase upper bridge arm and is connected with the corresponding diode pipe valve string through the heat dissipation pipeline of the corresponding diode pipe valve string;
and the second end of the water-cooling pipeline of each phase of lower bridge arm is respectively connected with each SM submodule through the heat dissipation pipeline of each SM submodule of each phase of lower bridge arm, and is connected with the corresponding diode pipe valve string through the heat dissipation pipeline of the corresponding diode pipe valve string.
6. The flexible DC transport system of claim 5,
each SM submodule in the electrical system is provided with a water inlet and a water outlet, and each diode pipe valve string is provided with a water inlet and a water outlet;
the upper bridge arm water-cooling main pipeline in the water-cooling system comprises an upper bridge arm water inlet main pipeline and an upper bridge arm water return main pipeline, the lower bridge arm water-cooling main pipeline comprises a lower bridge arm water inlet main pipeline and a lower bridge arm water return main pipeline,
the water cooling pipeline of each phase of upper bridge arm comprises a water inlet pipeline of each phase of upper bridge arm and a water return pipeline of each phase of upper bridge arm, the water cooling pipeline of each phase of lower bridge arm comprises a water inlet pipeline of each phase of lower bridge arm and a water return pipeline of each phase of lower bridge arm,
the heat dissipation pipeline of each SM submodule comprises a water inlet pipeline of each SM submodule and a water return pipeline of each SM submodule, and the heat dissipation pipeline of each diode pipe valve string comprises a water inlet pipeline of each diode pipe valve string and a water return pipeline of each diode pipe valve string;
wherein the content of the first and second substances,
the first end of the upper bridge arm water inlet main pipeline and the first end of the upper bridge arm water return main pipeline, and the first end of the lower bridge arm water inlet main pipeline and the first end of the lower bridge arm water return main pipeline are connected with the water supply device;
the first end of the water inlet pipeline of each phase upper bridge arm is connected with the second end of the water inlet main pipeline of the upper bridge arm, the first end of the water return pipeline of each phase upper bridge arm is connected with the second end of the water return main pipeline of the upper bridge arm,
the second end of the water inlet pipeline of each phase upper bridge arm is respectively connected with the water inlet of each SM submodule through the water inlet pipeline of each SM submodule of each phase upper bridge arm and is connected with the water inlet of the corresponding diode pipe valve string through the water inlet pipeline of the corresponding diode pipe valve string,
the second end of the water return pipeline of each phase of upper bridge arm is connected with the water return port of each SM submodule through the water return pipeline of each SM submodule of each phase of upper bridge arm, and is connected with the water outlet of the corresponding diode pipe valve string through the water return pipeline of the corresponding diode pipe valve string;
the first end of the water inlet pipeline of each phase of lower bridge arm is connected with the second end of the water inlet main pipeline of the lower bridge arm, the first end of the water return pipeline of each phase of lower bridge arm is connected with the second end of the water return main pipeline of the lower bridge arm,
the second end of the water inlet pipeline of each phase lower bridge arm is respectively connected with the water inlet of each SM submodule through the water inlet pipeline of each SM submodule of each phase lower bridge arm and is connected with the water inlet of the corresponding diode pipe valve string through the water inlet pipeline of the corresponding diode pipe valve string,
and the second end of the water return pipeline of each phase of lower bridge arm is connected with the water return port of each SM submodule through the water return pipeline of each SM submodule of each phase of lower bridge arm respectively, and is connected with the water outlet of the corresponding diode valve string through the water return pipeline of the corresponding diode valve string.
7. A diode valve string, comprising: m diode valve strings connected in series in the same direction, and overvoltage protectors arranged in parallel with the M diode valve strings connected in series in the same direction;
each diode pipe valve string comprises N diodes which are connected in series in the same direction, K water cooling plates, a first metal compression joint plate, an insulating support plate, a second metal compression joint plate and a compression joint fixing part;
in the arrangement direction of the N diodes connected in series in the same direction, the K water cooling plates and the N diodes are alternately arranged and connected in an equipotential manner, and the first water cooling plate and the Kth water cooling plate are respectively arranged at the head end and the tail end;
the first metal compression joint plate is in equipotential connection with one end of the first water cooling plate, and the other end of the first water cooling plate is in equipotential connection with the anode of the first diode;
one end of the insulating support plate is connected with the other end of the Kth water cooling plate, and the other end of the insulating support plate is connected with the second metal crimping plate; one end of the Kth water-cooling plate is connected with the cathode of the Nth diode in an equipotential manner;
one end of the compression joint fixing part is connected with the first metal compression joint plate, the other end of the compression joint fixing part is connected with the second metal compression joint plate, and the water cooling plate and the diode are fixed through compression joint among the first metal compression joint plate, the second metal compression joint plate and the compression joint fixing part;
the overvoltage protector comprises a first electrical interface and a second electrical interface, the first electrical interface is connected with an anode of the first diode valve string, the second electrical interface is connected with a cathode of the Mth diode valve string, and M, N and K are positive integers.
8. The diode valve string of claim 7,
the first water cooling plate in each diode pipe valve string is provided with a first electrical interface, the Kth water cooling plate in each diode pipe valve string is provided with a second electrical interface,
a first electrical interface in the first diode pipe valve string is connected with a direct current smoothing reactor, a second electrical interface in the Mth diode pipe valve string is connected with an MMC converter valve, or,
a first electrical interface in the first diode valve string is connected with the MMC converter valve, a second electrical interface in the Mth diode valve string is connected with the direct-current smoothing reactor,
the second electrical interface in the last diode valve string of two adjacent diode valve strings is connected with the first electrical interface in the next diode valve string, wherein K is N + 1.
9. The diode valve string of claim 7,
each water-cooled plate in each diode string includes a water inlet interface and a water outlet interface,
the water inlet interface of the first water cooling plate is used as the water inlet of the diode valve string, the water outlet interface of the Kth water cooling plate is used as the water outlet of the diode valve string,
and the water outlet interface of the last water cooling plate in the two adjacent water cooling plates is connected with the water inlet interface of the next water cooling plate to form a heat dissipation channel of the diode valve string.
10. The diode valve string of claim 7, wherein M equals 3;
n is less than or equal to 10.
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| CN201921005689.1U CN209823437U (en) | 2019-06-30 | 2019-06-30 | Flexible direct current transmission system, electrical system thereof and diode valve string |
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| CN201921005689.1U CN209823437U (en) | 2019-06-30 | 2019-06-30 | Flexible direct current transmission system, electrical system thereof and diode valve string |
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