CN220254367U - Cross-voltage-class two-port converter without transformer - Google Patents
Cross-voltage-class two-port converter without transformer Download PDFInfo
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- CN220254367U CN220254367U CN202321684549.8U CN202321684549U CN220254367U CN 220254367 U CN220254367 U CN 220254367U CN 202321684549 U CN202321684549 U CN 202321684549U CN 220254367 U CN220254367 U CN 220254367U
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Abstract
The utility model discloses a transformer-free two-port converter crossing voltage levels, which comprises a grid-connected converter, a first port lightning protection device, a second port lightning protection device and a filter lightning protection device group; one end of the filter lightning protection device group is connected with the grid-connected converter, and the other end of the filter lightning protection device group is connected with the first port lightning protection device and used as a first output port of the two-port converter; one end of the grid-connected converter is connected with the filter lightning arrester group, and the other end of the grid-connected converter is connected with the second port lightning arrester and is used as a second output port of the two-port converter; one end of the grid-connected converter is connected with the filter lightning arrester group, and the other end of the grid-connected converter is connected with the second port lightning arrester and is used as a second output port of the two-port converter; the transformer-free two-port converter crossing voltage levels is configured through a reasonable lightning protection device, so that direct grid connection of the transformer-free two-port network crossing voltage levels is realized, and new energy equipment is connected to the network at lower cost.
Description
Technical Field
The utility model relates to the technical field of power electronics, in particular to a transformer-free two-port converter with a cross-voltage class.
Background
Wind power generation is used as a main stream clean renewable energy source, has been developed in great extent in recent years, and with the development of a fan grid-connected power electronic conversion technology, the upper limit of the capacity of a single machine is continuously refreshed, the output voltage of a grid-connected converter is also increased from 690V to 1140V, and the trend of the voltage level of 10kV or even 35kV is towards. However, due to the difficulty of insulation design of a motor inside the fan, only a fan with a voltage level of 10kV can be realized at present, and wind power is required to be connected to a 35kV power distribution network after being converted by a converter, and all current grid-connected topologies are required to be connected to a power grid after being boosted by a transformer at present. Therefore, with the continuous improvement of the single-machine capacity of the wind turbine, the use of a large-capacity transformer causes difficulty in installation and maintenance as well as cost, and the use of the large-capacity transformer becomes a bottleneck for limiting the development of wind power.
Disclosure of Invention
The utility model aims to solve the technical problem of providing a transformer-free two-port converter of a voltage-crossing grade, wherein the transformer-free two-port converter of the voltage-crossing grade is configured through a reasonable lightning protection device so as to realize direct grid connection of a network of the two ports without the transformer across the voltage-crossing grade, thereby realizing network access of new energy equipment with lower cost.
In order to solve the technical problems, the utility model provides a transformer-free two-port converter crossing voltage levels, which is used for connecting two three-phase systems with different voltage frequencies, wherein the two-port converter comprises a grid-connected converter, a first-port lightning arrester, a second-port lightning arrester and a filter lightning arrester group;
one end of the filter lightning protection device group is connected with the grid-connected converter, and the other end of the filter lightning protection device group is connected with the first port lightning protection device and used as a first output port of the two-port converter;
and one end of the grid-connected converter is connected with the filter lightning arrester group, and the other end of the grid-connected converter is connected with the second port lightning arrester and is used as a second output port of the two-port converter.
Preferably, the first output port is connected with a 35kV power grid, the second output port is connected with a 10kV motor, the first port lightning arrester is a network side lightning arrester, and the second port lightning arrester is a machine side lightning arrester.
Preferably, the rated voltage of the grid-side input end of the grid-connected converter is 35kV, and the rated voltage of the machine-side output end of the grid-connected converter is 10kV.
Preferably, the grid-connected converter is a modular multilevel matrix converter.
Preferably, the filter lightning protection device group comprises a front-end filter inductor, a rear-end filter inductor, a filter capacitor and a filter neutral point lightning protection device;
the front-end filter inductor, the rear-end filter inductor and the filter capacitor jointly form a second-order low-pass filter, the filter capacitor is connected with the front-end filter inductor and the rear-end filter inductor in a star connection mode, and the filter neutral point lightning arrester is connected between a neutral point formed by star connection of the filter capacitor and the ground.
Preferably, the power frequency withstand voltage of the 10kV motor is larger than the sum of the rated voltage of the network side lightning arrester and the rated voltage effective value of the machine side lightning arrester.
After the converter is adopted, the transformer-free two-port converter crossing the voltage level comprises a grid-connected converter, a first port lightning protection device, a second port lightning protection device and a filter lightning protection device group;
one end of the grid-connected converter is connected with the filter lightning arrester group, and the other end of the grid-connected converter is connected with the second port lightning arrester and is used as a second output port of the two-port converter;
one end of the filter lightning protection device group is connected with the grid-connected converter, and the other end of the filter lightning protection device group is connected with the first port lightning protection device and used as a first output port of the two-port converter; the transformer-free two-port converter crossing voltage levels is configured through a reasonable lightning protection device, so that direct grid connection of the transformer-free two-port network crossing voltage levels is realized, and new energy equipment is connected to the network at lower cost.
Drawings
FIG. 1 is an overall circuit diagram of an inventive transformer-less two-port converter across voltage classes;
fig. 2 is a circuit diagram of a grid-connected inverter employing a modular multilevel matrix inverter structure without a transformer across voltage classes of the utility model.
The realization, functional characteristics and advantages of the present application will be further described with reference to the embodiments, referring to the attached drawings.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved by the application clearer and more obvious, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
In the description of the present application, it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of description of the present application and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Example 1
Referring to fig. 1, fig. 1 is an overall circuit diagram of a transformer-less two-port converter of the present utility model across voltage classes;
the embodiment discloses a voltage-class-crossing two-port converter without a transformer, which is used for connecting two three-phase systems with different voltage frequencies, wherein the two-port converter comprises a grid-connected converter 71, a first-port lightning arrester 72, a second-port lightning arrester 73 and a filter lightning arrester group 74;
one end of the filter lightning arrester group 74 is connected with the grid-connected converter 71, and the other end is connected with the first port lightning arrester 72 and is used as a first output port 75 of the two-port converter; one end of the grid-connected converter 71 is connected with the filter lightning arrester group 74, and the other end is connected with the second port lightning arrester 73 and is used as a second output port 76 of the two-port converter;
example two
In this embodiment, the first output port 75 is connected to the 35kV power grid 6, the second output port 76 is connected to the 10kV motor 5, the first port lightning arrester 72 is a network side lightning arrester, and the second port lightning arrester 73 is a machine side lightning arrester.
The 10kV motor 5 is a Permanent Magnet Synchronous Motor (PMSM) and has a rated voltage class of 10kV.
The rated voltage of the network side lightning protection device is selected according to a voltage class of 35kV, and the residual voltage of lightning impulse current does not exceed the insulation tolerance level of a 35kV system;
the rated voltage of the machine side lightning protector is selected according to the voltage class of 10kV, and the residual voltage of lightning impulse current does not exceed the insulation tolerance level of a 10kV system.
Example III
In the second embodiment, the rated voltage of the grid-side input end of the grid-connected converter 71 is 35kV, the rated voltage of the machine-side output end of the grid-connected converter is 10kV, the working frequency of the grid-side is the same as the frequency of the power grid, and the working frequency of the machine-side can be adapted to the output frequency of the electric machine.
Example IV
Referring to fig. 2, fig. 2 is a circuit diagram of a grid-connected converter of a cross-voltage-class two-port converter without a transformer adopting a modularized multi-level matrix converter structure;
the present embodiment is based on the first embodiment, in which the grid-connected inverter 71 is a modular multilevel matrix inverter.
Example five
The filter lightning arrester 74 comprises a front-end filter inductance 741, a rear-end filter inductance 742, a filter capacitance 743 and a filter neutral lightning arrester 744;
the front filter inductance 741, the rear filter inductance 742 and the filter capacitance 743 together form a second-order low-pass filter, the filter capacitance 743 is connected with the front filter inductance 741 and the rear filter inductance 742 in a star connection mode, and the filter neutral point lightning arrester 744 is connected between a neutral point formed by the star connection of the filter capacitance 743 and the ground.
Example six
In the embodiment, the power frequency withstand voltage of the 10kV motor 5 is larger than the sum of the rated voltage of the network side lightning arrester and the rated voltage effective value of the machine side lightning arrester.
According to the embodiment, through the configuration of the lightning protection devices of the two-port network with different voltage levels, lightning invasion waves from the side with higher voltage levels are limited by the three-level lightning protection devices, so that loads on the side with lower voltage levels can be reliably protected, and transient voltage can drop on the inductance of the filter to a greater extent. Meanwhile, under the condition that the insulation level of the 10kV load can withstand 45kV short-time power frequency withstand voltage (GB 311.1 requires short-time power frequency dry-type withstand voltage 42kV of the 10kV load), even if the short-circuit to ground of the network side single-phase occurs, the short-time rise of the machine side voltage to ground is caused, and the fault of insulation failure can not occur. The final topology scheme realizes that the load with low voltage class is not directly hung on the high-voltage power grid through the transformer through reasonable insulation matching.
The transformer-free two-port converter crossing voltage levels is configured through a reasonable lightning protection device, so that direct grid connection of the transformer-free two-port network crossing voltage levels is realized, and new energy equipment is connected to the network at lower cost.
The preferred embodiments of the present application have been described above with reference to the accompanying drawings, and are not thereby limiting the scope of the claims of the present application. Any modifications, equivalent substitutions and improvements made by those skilled in the art without departing from the scope and spirit of the present application shall fall within the scope of the claims of the present application.
Claims (6)
1. The transformer-free two-port converter of the voltage class is characterized by being used for connecting two three-phase systems with different voltage frequencies, wherein the two-port converter comprises a grid-connected converter, a first-port lightning arrester, a second-port lightning arrester and a filter lightning arrester group;
one end of the filter lightning protection device group is connected with the grid-connected converter, and the other end of the filter lightning protection device group is connected with the first port lightning protection device and used as a first output port of the two-port converter;
and one end of the grid-connected converter is connected with the filter lightning arrester group, and the other end of the grid-connected converter is connected with the second port lightning arrester and is used as a second output port of the two-port converter.
2. The transformer-free two-port converter of claim 1, wherein the first output port is connected to a 35kV power grid, the second output port is connected to a 10kV motor, the first port lightning arrester is a grid-side lightning arrester, and the second port lightning arrester is a machine-side lightning arrester.
3. The transformer-less two-port converter of claim 2, wherein the grid-side input voltage rating of the grid-tied converter is 35kV and the machine-side output voltage rating of the grid-tied converter is 10kV.
4. The transformer-less two-port converter of claim 1, wherein the grid-tied converter is a modular multilevel matrix converter.
5. The transformer-less two-port transformer across voltage classes of claim 1, wherein the filter lightning protection bank comprises a front-end filter inductance, a back-end filter inductance, a filter capacitance, and a filter neutral point lightning protection;
the front-end filter inductor, the rear-end filter inductor and the filter capacitor jointly form a second-order low-pass filter, the filter capacitor is connected with the front-end filter inductor and the rear-end filter inductor in a star connection mode, and the filter neutral point lightning arrester is connected between a neutral point formed by star connection of the filter capacitor and the ground.
6. A transformer-less two-port converter of claim 3, wherein the power frequency withstand voltage of the 10kV motor is greater than a sum of the net-side lightning protection device rated voltage and the machine-side lightning protection device rated voltage effective value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321684549.8U CN220254367U (en) | 2023-06-29 | 2023-06-29 | Cross-voltage-class two-port converter without transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321684549.8U CN220254367U (en) | 2023-06-29 | 2023-06-29 | Cross-voltage-class two-port converter without transformer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220254367U true CN220254367U (en) | 2023-12-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202321684549.8U Active CN220254367U (en) | 2023-06-29 | 2023-06-29 | Cross-voltage-class two-port converter without transformer |
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| Country | Link |
|---|---|
| CN (1) | CN220254367U (en) |
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2023
- 2023-06-29 CN CN202321684549.8U patent/CN220254367U/en active Active
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