CN212991967U - Energy absorption circuit for direct current system - Google Patents
Energy absorption circuit for direct current system Download PDFInfo
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- CN212991967U CN212991967U CN202021702575.5U CN202021702575U CN212991967U CN 212991967 U CN212991967 U CN 212991967U CN 202021702575 U CN202021702575 U CN 202021702575U CN 212991967 U CN212991967 U CN 212991967U
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Abstract
The utility model provides an energy absorption circuit for a direct current system, which is connected between a positive direct current bus and a negative direct current bus of the direct current system and comprises a reactor and a plurality of submodules which are connected in series; the submodule piece includes a plurality of diodes and with diode connection's direct current voltage-sharing and power consumption circuit, through setting up the reactor, greatly reduced energy absorption circuit transient state electrical stress in charging process, reduced the damage probability of device, reduce the electrical design margin of submodule piece cluster, with low costs, the utility model provides a reactor can effectively restrain the electric current sudden change, restrain the transient state electrical stress that energy absorption circuit bore in charging process, and voltage-sharing resistance can realize each submodule piece voltage-sharing, avoided can turn-off the device and establish ties, can turn-off the device and bear electrical stress for a short time, the utility model provides an energy absorption circuit when the submodule piece breaks down, the mechanical switch of closed trouble submodule piece will break down the submodule piece bypass, has improved direct current system's operational reliability.
Description
Technical Field
The utility model relates to a direct current power transmission and distribution technical field, concretely relates to an energy absorption circuit for direct current system.
Background
The current power transmission and distribution technology mainly comprises two modes, namely alternating current power transmission and distribution and direct current power transmission and distribution. Currently, ac power transmission and distribution technology still dominates. However, in application scenarios such as high-voltage, long-distance, large-capacity power transmission, ac power grid interconnection and the like, an ac power transmission system has the disadvantages of wide power corridor, lack of stability, limited capacity and the like, and the problems of large reactive compensation capacity and difficult voltage control exist when cable power supply is adopted; in the scene of supplying power to a direct current load, the alternating current power distribution mode has the defects of multiple conversion levels, low efficiency and the like. Compared with alternating current transmission, direct current transmission has the advantages of low investment, low running loss and the like in long-distance transmission, and the flexible direct current transmission mode is adopted without specially setting reactive compensation equipment, so that the system is very suitable for offshore and onshore wind power plant grid connection, power grid interconnection, island and weak grid power supply and urban power supply.
The direct-current transmission system mainly comprises a direct-current transmission system (LCC) based on power grid commutation, a flexible direct-current transmission system (VSC) based on a voltage source converter and a hybrid direct-current transmission system based on the LCC and the VSC. When an alternating current system fails, overvoltage can occur in the direct current system, the safety of equipment and a power grid is seriously endangered, and measures need to be taken to quickly and controllably absorb overvoltage energy of the direct current system.
In the existing energy absorption device of the distributed direct current system, power devices/modules and absorption resistors are distributed dispersedly, each bridge arm of an IGBT/IGCT valve is formed by connecting a plurality of sub-modules (SM) in series, and each sub-module can be controlled independently. Each submodule corresponds to a separate snubber resistor, and when the IGBTs in the submodule are turned on, the submodule resistors put in and consume active power. By controlling the number of the added sub-modules, the power consumed by the absorption circuit can be continuously adjusted, relatively smooth working characteristics are realized, the circuit is easy to adapt to faults of different degrees, and meanwhile, the direct series connection of switching devices can be avoided. The larger the number of sub-modules, the smoother the power regulation characteristic. However, the existing energy absorption device of the distributed direct current system has large transient electrical stress in the charging process, so that the device is easy to damage.
SUMMERY OF THE UTILITY MODEL
In order to overcome the defect that the transient electrical stress is large and easily causes the damage of the device in the prior art, the utility model provides an energy absorption circuit for a direct current system, which is connected between a positive direct current bus and a negative direct current bus of the direct current system and comprises a reactor and a plurality of submodules which are connected in series;
the submodule comprises a plurality of diodes and a direct current voltage-sharing and energy-consuming circuit connected with the diodes.
The plurality of sub-modules comprises a first diode (1), a second diode (2), a third diode (3) and a fourth diode (4);
the direct current voltage-sharing and energy-consuming circuit comprises an energy storage capacitor (5), a turn-off device (6), an absorption resistor (7) and an energy taking unit;
the anode of the first diode (1) is connected with the cathode of the second diode (2) to serve as a first port of the submodule, the anode of the third diode (3) is connected with the cathode of the fourth diode (4) to serve as a second port of the submodule, the cathodes of the first diode (1) and the third diode (3) are connected with a common point A, the anodes of the second diode (2) and the fourth diode (4) are connected with a common point B, two ends of the energy storage capacitor (5) are connected with the common point A and the common point B respectively, and the turn-off device (6) and the absorption resistor (7) are connected between the common point A and the common point B after being connected in series;
the energy taking unit is connected with the energy storage capacitor (5).
The number of the reactors is 1 or two.
When the number of the electric reactors is 1 and the energy absorption circuit is connected to a unidirectional bias direct current system, the positive direct current bus or the negative direct current bus is grounded.
When the inductance values of the 2 reactors are equal, and the energy absorption circuit is connected into a symmetrical unipolar direct current system or a true bipolar direct current system, the two reactors are connected with the plurality of sub-modules in series, and the midpoint position of the energy absorption circuit is grounded.
The submodule also comprises a voltage-sharing resistor (8);
and two ends of the voltage-sharing resistor (8) are respectively connected with the common point A and the common point B.
The submodule further comprises a fifth diode (9);
the fifth diode (9) is connected in parallel with the absorption resistor (7), and the anode of the fifth diode is connected with the common point B.
The sub-module further comprises a mechanical switch (10);
and two ends of the mechanical switch (10) are respectively connected with the first port and the second port.
The sub-modules further comprise voltage sensors mounted between the common point a and the common point B.
The utility model provides a technical scheme has following beneficial effect:
the utility model provides an energy absorption circuit for a direct current system, which is connected between a positive direct current bus and a negative direct current bus of the direct current system and comprises a reactor and a plurality of submodules which are connected in series; the submodule comprises a plurality of diodes and a direct current voltage-sharing and energy-consuming circuit connected with the diodes, and through the arrangement of the reactor, the transient electrical stress of the energy absorption circuit in the charging process is greatly reduced, and the damage probability of the device is reduced;
the energy absorption circuit provided by the utility model reduces the electrical design margin of the sub-module string, and has low cost;
the utility model provides a first diode (1), second diode (2), third diode (3), fourth diode (4) constitute the rectifier circuit of not controlling, make energy absorption circuit can bear positive negative pole bus voltage reversal through the rectifier circuit of not controlling, under operating mode such as direct current utmost point bus voltage reversal, can not cause the short circuit between the positive negative pole bus, are favorable to the quick recovery of direct current system;
the reactor in the utility model can effectively restrain the current mutation and restrain the transient electric stress born by the energy absorption circuit in the charging process;
the utility model realizes voltage sharing of each submodule through the voltage sharing resistor, avoids the series connection of the turn-off devices, and the turn-off devices bear small electrical stress;
in the utility model, each submodule adopts a turn-off device to discharge, diodes are connected in parallel at two ends of the absorption resistor, and when the turn-off device is turned off, the current on the equivalent inductance of the absorption resistor can follow current through the diodes, so that the surge voltage electrical stress born by the turn-off device is reduced;
the utility model provides an energy absorption circuit is when the submodule piece breaks down, and the mechanical switch of closed trouble submodule piece has improved direct current system's operational reliability with trouble submodule piece bypass.
Drawings
Fig. 1 is a diagram of an energy absorption circuit for a dc system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a reactor and a plurality of sub-modules connected in series in the embodiment of the present invention;
fig. 3 is a schematic diagram of two reactors and a plurality of sub-modules connected in series in the embodiment of the present invention;
fig. 4 is a specific structure diagram of an energy absorption circuit for a dc system according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The embodiment of the utility model provides an energy absorption circuit for direct current system, as shown in fig. 1, the energy absorption circuit is connected between the positive pole direct current generating line and the negative pole direct current generating line of direct current system, including reactor and a plurality of submodule pieces (SM) of establishing ties; the plurality of sub-modules are connected in series to form a sub-module string, and the reactor can be connected in series at any position in the middle of the sub-module string, between the sub-module string and the positive direct-current bus, between the sub-module string and the negative direct-current bus, or at any position in the middle of the sub-modules.
The submodule comprises a plurality of diodes and a direct current voltage-sharing and energy-consuming circuit connected with the diodes;
the plurality of diodes are used for rectifying the positive polarity voltage or the negative polarity voltage of the direct current system into a positive polarity voltage;
the direct current voltage-sharing and energy-consuming circuit is used for carrying out voltage sharing and energy dissipation on the sub-modules;
the reactor is used for suppressing a charging surge current of the energy absorption circuit.
The plurality of diodes comprise a first diode 1, a second diode 2, a third diode 3 and a fourth diode 4;
the direct current voltage-sharing and energy-consuming circuit comprises an energy storage capacitor 5, a turn-off device 6, an absorption resistor 7 and an energy taking unit;
the anode of the first diode 1 is connected with the cathode of the second diode 2 to serve as a first port of the submodule, the anode of the third diode 3 is connected with the cathode of the fourth diode 4 to serve as a second port of the submodule, the cathodes of the first diode 1 and the third diode 3 are respectively connected with a common point A, the anodes of the second diode 2 and the fourth diode 4 are respectively connected with a common point B, two ends of the energy storage capacitor 5 are respectively connected with the common point A and the common point B, and the turn-off device 6 and the absorption resistor 7 are connected between the common point A and the common point B after being connected in series; the absorption resistor 7 is used for absorbing energy and absorbing energy in a PWM mode.
The energy taking unit is connected with the energy storage capacitor 5 and used for obtaining electric energy from the energy storage capacitor 5.
The number of the reactors is 1 or two, and the reactors are only connected with a plurality of sub-modules in series no matter 1 or two reactors are arranged. The embodiment 1 of the utility model provides an in, as shown in fig. 2, when the reactor is 1, a plurality of submodule pieces are established ties and are formed the submodule piece cluster, and submodule piece cluster one end is connected through this reactor and direct current system's anodal direct current generating line, and the other end is connected with direct current system's negative pole direct current generating line, and this reactor setting is between submodule piece cluster and anodal direct current generating line promptly. As shown in fig. 3, when there are 2 reactors, a plurality of submodules are connected in series to form a submodule string, one end of the submodule string is connected to the positive dc bus of the dc system through one of the reactors, and the other end of the submodule string is connected to the negative dc bus of the dc system through another one of the reactors, that is, one of the reactors is disposed between the submodule string and the positive dc bus, and the other reactor is disposed between the submodule string and the negative dc bus.
When the number of the electric reactors is 1 and the energy absorption circuit is connected into the unidirectional bias direct current system, the positive direct current bus or the negative direct current bus is grounded.
When the number of the electric reactors is 2, the inductance values of the two electric reactors are equal, and the energy absorption circuit is connected into a symmetrical unipolar direct current system or a true bipolar direct current system, the two electric reactors are connected with the plurality of sub-modules in series, and the midpoint position of the energy absorption circuit is grounded.
As shown in fig. 4, the submodule in embodiment 1 of the present invention further includes a voltage-sharing resistor 8;
and two ends of the voltage-sharing resistor 8 are respectively connected with the common point A and the common point B for realizing capacitor voltage sharing of each submodule.
The submodule in embodiment 1 of the present invention further includes a fifth diode 9;
a fifth diode 9 is connected in parallel with the snubber resistor 7 and has its anode connected to the common point B for reducing the turn-off surge voltage of the turn-off device 6.
The submodule in embodiment 1 of the present invention further includes a mechanical switch 10;
the two ends of the mechanical switch 10 are respectively connected with the first port and the second port, and the mechanical switch is used for bypassing the sub-module when the sub-module fails.
The sub-module further includes:
and the voltage sensor is arranged between the common point A and the common point B and used for measuring the terminal voltage of the energy storage capacitor 5.
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same, and those skilled in the art can still modify or equally replace the specific embodiments of the present invention with reference to the above embodiments, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are all within the scope of the present invention to be applied.
Claims (9)
1. An energy absorption circuit for a direct current system is characterized in that the energy absorption circuit is connected between a positive direct current bus and a negative direct current bus of the direct current system and comprises a reactor and a plurality of sub-modules which are connected in series;
the submodule comprises a plurality of diodes and a direct current voltage-sharing and energy-consuming circuit connected with the diodes.
2. The energy absorption circuit for a direct current system according to claim 1, wherein the plurality of diodes comprises a first diode (1), a second diode (2), a third diode (3) and a fourth diode (4);
the direct current voltage-sharing and energy-consuming circuit comprises an energy storage capacitor (5), a turn-off device (6), an absorption resistor (7) and an energy taking unit;
the anode of the first diode (1) is connected with the cathode of the second diode (2) to serve as a first port of the submodule, the anode of the third diode (3) is connected with the cathode of the fourth diode (4) to serve as a second port of the submodule, the cathodes of the first diode (1) and the third diode (3) are connected with a common point A, the anodes of the second diode (2) and the fourth diode (4) are connected with a common point B, two ends of the energy storage capacitor (5) are connected with the common point A and the common point B respectively, and the turn-off device (6) and the absorption resistor (7) are connected between the common point A and the common point B after being connected in series;
the energy taking unit is connected with the energy storage capacitor (5).
3. The energy absorption circuit for a direct current system according to claim 1, wherein the number of the reactors is 1 or two.
4. The energy absorption circuit for the direct current system according to claim 3, wherein the number of the reactors is 1, and when the energy absorption circuit is connected to a unidirectional bias direct current system, the positive direct current bus or the negative direct current bus is grounded.
5. The energy absorption circuit for the direct current system according to claim 3, wherein the inductance of the reactors is 2, the inductance of two reactors is equal, and when the energy absorption circuit is connected into a symmetrical unipolar direct current system or a true bipolar direct current system, two reactors are connected with a plurality of sub-modules in series, and the midpoint of the energy absorption circuit is grounded.
6. The energy absorption circuit for a direct current system according to claim 2, wherein the sub-module further comprises a voltage grading resistor (8);
and two ends of the voltage-sharing resistor (8) are respectively connected with the common point A and the common point B.
7. Energy absorption circuit for direct current systems according to claim 2, characterized in that said sub-module further comprises a fifth diode (9), said fifth diode (9) being connected in parallel with the absorption resistor (7) and having its anode connected to the common point B.
8. The energy absorption circuit for a direct current system according to claim 2, wherein the sub-module further comprises a mechanical switch (10), and the two ends of the mechanical switch (10) are respectively connected with the first port and the second port.
9. The energy absorbing circuit for a dc system of claim 8, wherein the sub-modules further comprise a voltage sensor mounted between a common point a and a common point B.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021702575.5U CN212991967U (en) | 2020-08-14 | 2020-08-14 | Energy absorption circuit for direct current system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021702575.5U CN212991967U (en) | 2020-08-14 | 2020-08-14 | Energy absorption circuit for direct current system |
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| Publication Number | Publication Date |
|---|---|
| CN212991967U true CN212991967U (en) | 2021-04-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021702575.5U Active CN212991967U (en) | 2020-08-14 | 2020-08-14 | Energy absorption circuit for direct current system |
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| Country | Link |
|---|---|
| CN (1) | CN212991967U (en) |
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- 2020-08-14 CN CN202021702575.5U patent/CN212991967U/en active Active
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