CN111416332A - Suppression device for direct current - Google Patents
Suppression device for direct current Download PDFInfo
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- CN111416332A CN111416332A CN202010181817.9A CN202010181817A CN111416332A CN 111416332 A CN111416332 A CN 111416332A CN 202010181817 A CN202010181817 A CN 202010181817A CN 111416332 A CN111416332 A CN 111416332A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/08—Limitation or suppression of earth fault currents, e.g. Petersen coil
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
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Abstract
The invention discloses a direct current suppression device which is used for being connected into a device circuit needing to suppress direct current. It includes: the device comprises a current detection module, a pulse trigger control module, a first switch module, a second switch module, an inductance module and a resistance module; wherein the first switch module comprises a set of power electronic switches connected in anti-parallel. The first switch module is connected with the second switch module in parallel and then connected with the current detection module in series; the pulse trigger control module is connected with the first switch module; and the inductance module is connected with the first switch module in series after being connected with the resistance module in series. Through controlling the repeated on-off of the first switch module, the inductance module restrains the direct current entering the ground at a lower level, so that the influence on the normal operation of peripheral equipment flowing into the ground due to the fact that the overlarge direct current enters the ground is effectively avoided, the safe operation of the equipment is ensured, and the service life of the equipment is prolonged.
Description
Technical Field
The invention relates to the technical field of electrical engineering, in particular to a direct current suppression device.
Background
With the development of electrical engineering technology in China, direct current transmission is more and more widely applied to a power grid, and plays a very positive role in a power system. However, the application of direct current transmission also brings about a plurality of influence problems. For example, when a direct current to ground flows into a neutral point of a transformer, the direct current magnetic bias problem of the transformer can be caused, so that the transformer vibrates, harmonic waves are increased, noise is increased, temperature is too high, and the like, and in a serious case, the transformer is damaged, and finally the safe operation of a power grid is influenced.
In order to avoid the problem of dc magnetic bias caused by dc current flowing into the neutral point of the grounding transformer, researchers have proposed various methods for suppressing dc current at the neutral point of the transformer, such as a reverse injection current method, a neutral point series capacitance method, and the like. However, the inventor finds that the conventional measures and devices for suppressing the direct current of the neutral point of the transformer have the defects of poor direct current suppression effect, complex device structure and the like in the process of implementing the invention.
Disclosure of Invention
The purpose of the embodiments of the present invention is to provide a dc current suppression device, which can effectively suppress the dc current entering the ground, and avoid that the excessive dc current enters the ground and affects the normal operation of the peripheral devices at the dc entering the ground, thereby ensuring the safe operation of the devices and prolonging the service life of the devices.
In order to achieve the above object, an embodiment of the present invention provides a dc current suppressing apparatus, including: the device comprises a current detection module, a pulse trigger control module, a first switch module and a second switch module; wherein the first switch module comprises a set of power electronic switches connected in anti-parallel;
the first switch module is connected with the second switch module in parallel and then connected with the current detection module in series; the pulse trigger control module is connected with the first switch module;
the current detection module is used for detecting the current magnitude and the current direction on the loop; sending a control signal to control the working state of the pulse trigger control module and the on-off of the second switch module according to the current magnitude and the current direction;
the pulse trigger control module is used for sending a trigger pulse to control the on-off of a power electronic switch which is consistent with the flow direction of the direct current in the first switch module when the first switch module is started to work.
As an improvement of the above scheme, the dc current suppressing device further includes an inductance module and a resistance module;
and the inductance module is connected with the first switch module in series after being connected with the resistance module in series.
As an improvement of the above scheme, the control signal sent by the current detection module includes a first control signal and a second control signal;
the first control signal is used for controlling the pulse trigger control module to stop working and controlling the second switch module to be closed;
the second control signal is used for controlling the pulse trigger control module to start and work and controlling the second switch module to be switched off.
As an improvement of the above scheme, the current detection module detects the current magnitude and the current direction on the loop; and according to the current magnitude and the current direction, sending a control signal to control the working state of the pulse trigger control module and the on-off of the second switch module specifically comprises:
the current detection module detects the magnitude of direct current on a loop;
when the direct current on the loop is judged to be smaller than a preset current threshold value, the first control signal is sent out;
when the direct current is judged to be larger than or equal to the preset current threshold value, the directions of the alternating current and the direct current on the loop are detected, and when the alternating current and the direct current are judged to be in the same direction, the second control signal is sent.
As an improvement of the above scheme, when the pulse trigger control module is started to operate, the pulse trigger control module sends out a trigger pulse to control on/off of a power electronic switch in the first switch module, which is consistent with a direct current flow direction, and specifically includes:
after the pulse trigger control module is started to work, sending trigger pulses every other first preset time to close the power electronic switch consistent with the direct current flow direction;
after a second preset time, stopping sending a trigger pulse by the pulse trigger control module so as to disconnect the power electronic switch consistent with the direct current flow direction;
the second preset time length is less than the first preset time length; the first preset time is the direction change period of alternating current on the loop; the second preset time length is the time length that the alternating current and the direct current are in the same direction in the direction change period.
As an improvement of the above solution, the dc current suppressing device further includes a third switching module; the third switch module is connected in series with the first switch module.
As an improvement of the above scheme, the first control signal is further used for controlling the third switch module to be turned off; the second control signal is also used to control the third switch module to close.
As an improvement of the above scheme, the dc current suppressing device further includes a circuit protection module;
the circuit protection module is connected with the first switch module in parallel and used for protecting the first switch module from being broken down.
As an improvement of the scheme, the circuit protection module comprises but is not limited to a protection gap, an RC resistance-capacitance loop and an arrester.
As an improvement of the above scheme, the power electronic switch in the first switch module is a thyristor or an IGBT power electronic switch.
Compared with the prior art, the direct current suppression device disclosed by the invention is used for being connected into a device circuit needing to suppress direct current. The repeated on-off of the first switch module is controlled, the inductance module in the equipment or the inductance module arranged in the suppression device of the direct current is utilized to suppress the rising rate of the direct current in the loop and prolong the time of the direct current reaching a stable value, so that the direct current entering the ground is suppressed at a lower level, the phenomenon that the overlarge direct current enters the ground and influences the normal operation of peripheral equipment flowing into the ground is effectively avoided, the safe operation of the equipment is ensured, and the service life of the equipment is prolonged. In addition, the suppression device for the direct current has a simple structure, and can effectively save installation space and manufacturing cost.
Drawings
Fig. 1 is a schematic structural diagram of a dc current suppressing apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a dc loop according to an embodiment of the present invention;
fig. 3 is a schematic flowchart of a current detection module in the dc current suppression device according to an embodiment of the present invention;
fig. 4 is a schematic flowchart of the start-up operation of the pulse trigger control module in the dc current suppression device according to the first embodiment of the present invention;
fig. 5 is a schematic structural diagram of another dc current suppressing apparatus according to a second embodiment of the present invention;
fig. 6 is a schematic structural diagram of a dc current suppressing apparatus according to a third preferred embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic structural diagram of a dc current suppression device according to a first embodiment of the present invention. In an embodiment of the present invention, the dc current suppression device 10 includes: the device comprises a current detection module 11, a pulse trigger control module 12, a first switch module 13 and a second switch module 14; wherein the first switch module 13 comprises a set of anti-parallel power electronic switches S1 and S2.
Preferably, the power electronic switches S1 and S2 in the first switch module 13 are thyristor or IGBT power electronic switches.
The first switch module 13 is connected in parallel with the second switch module 14, and then connected in series with the current detection module 11; the pulse trigger control module 12 is connected to the first switch module 13.
The current detection module 11 is used for detecting the current magnitude and the current direction on the loop; and sending out a control signal to control the working state of the pulse trigger control module 12 and the on-off of the second switch module 14 according to the current magnitude and the current direction.
The pulse trigger control module 12 is configured to send a trigger pulse to control on/off of a power electronic switch in the first switch module 13, which is consistent with a direct current flow direction, when the power electronic switch is started to operate.
The operation of the dc current suppressing apparatus 10 will be described in detail below. Fig. 2 is a schematic structural diagram of a dc circuit according to a first embodiment of the present invention. Where Vdc represents direct current, R0Representing resistance, L0Representing an inductance and S a switch.
When the switch S is closed, a DC current is generated in the loop and is received by the inductor L0In such a way that the direct current in the circuit does not immediately reach a stable value I∞＝Vdc/R0But rather gradually increases from 0 to a steady value I∞That is, after the switch S is closed, a certain transient time τ is needed for the dc current to reach the stable value I∞. During this transient, the following equation can be written in terms of circuit principles:
further, if inductance L is in the loop0Far greater than resistance R0When the switch S is just closed, the above formula can be simplified as:
at this time, the rising rate of the dc current and the inductance L0Correlation if inductance L0The larger the DC currentThe smaller the rise rate of (D) is, the more stable the direct current reaches I∞The longer the time of the switch S is, therefore, in the dc circuit shown in fig. 2, the switch S is closed and then receives the inductor L0If the switch S is controlled to be switched off in the increasing process, the direct current can be immediately reduced to 0 because the direct current power supply is cut off at the moment, and then the switch S is switched on, so that the direct current can be continuously increased from 0.
Based on the above working principle, the dc current suppressing apparatus 10 according to the first embodiment of the present invention is used to be connected to a device circuit with an inductance module, for example, to connect a transformer, so as to suppress the dc current at the neutral point of the transformer.
Specifically, the first switch module 13 includes a set of power electronic switches S1 and S2 connected in inverse parallel, and since the direction of the dc current in the loop is single, by detecting the direction of the dc current in the loop, the power electronic switch S1 in the first switch module 13, which is consistent with the direction of the dc current, is set to be turned off at a certain frequency to suppress the magnitude of the dc current; and the other power electronic switch S2, which is not in line with the dc current, is normally closed, thereby providing a path for the ac current in the loop.
Further, the process of controlling the power electronic switch S1 consistent with the direct current flow direction to turn off according to a certain frequency is specifically realized by the pulse trigger control module 12, and the pulse trigger control module 12 is controlled to send out a trigger pulse according to a certain frequency, so that the power electronic switch S1 consistent with the direct current flow direction is closed when receiving the trigger pulse, and is opened when losing the trigger pulse. Therefore, when the switch S1 is closed, the dc current in the loop gradually increases from 0 due to the suppression of the inductance of the connected device with inductance module, such as a transformer, and when the switch S1 is opened, the dc current immediately decreases to 0.
In a preferred embodiment, the frequency of the trigger pulse sent by the pulse trigger control module 12 is set appropriately, so that the switch S1 is closed when the alternating current and the direct current in the loop are in the same direction, and is opened when the alternating current and the direct current in the loop are in the opposite direction, thereby ensuring that a path is provided for the alternating current in the loop at any time.
Further, the process of controlling the pulse trigger control module 12 to send out the trigger pulse is realized by the current detection module 11. The current detection module 11 is used for detecting the current magnitude and the current direction on the loop; and sending out a control signal to control the working state of the pulse trigger control module 12 and the on-off of the second switch module 14 according to the current magnitude and the current direction.
The working state of the pulse trigger control module 12 includes start-up and stop.
In a preferred embodiment, referring to fig. 3, a schematic flowchart of a current detection module in a dc current suppression device according to a first embodiment of the present invention is shown.
The control signal sent by the current detection module 11 includes a first control signal and a second control signal. The first control signal is used for controlling the pulse trigger control module 12 to stop working and controlling the second switch module 14 to be closed; the second control signal is used for controlling the pulse trigger control module 12 to start working and controlling the second switch module 14 to be switched off.
The current detection module 11 detects the current magnitude and the current direction on the loop; and sending a control signal to control the working state of the pulse trigger control module and the on-off of the second switch module according to the current magnitude and the current direction, and specifically comprising the steps of S11 to S13:
and S11, the current detection module detects the magnitude of the direct current on the loop.
And S12, when the direct current on the loop is judged to be smaller than a preset current threshold value, sending the first control signal.
And S13, when the direct current is judged to be larger than or equal to the preset current threshold value, detecting the directions of the alternating current and the direct current on the loop, and when the alternating current and the direct current are judged to be in the same direction, sending the second control signal.
Specifically, the dc current suppression device 10 is connected to a device circuit with an inductance module, such as a transformer in a power grid, which needs to suppress dc current. A direct current threshold value influencing the normal operation of the access equipment is preset and used as a preset current threshold value. The current detection module 11 is configured to detect a magnitude of a direct current on the loop.
When the current detection module 11 detects that the direct current is smaller than the preset current threshold, the current detection module 11 sends a first control signal to the pulse trigger control module 12 and the second switch module 14. When receiving the first control signal, the pulse trigger control module 12 stops working, that is, stops sending a trigger pulse to open the power electronic switch S1 in the first switch module that is in accordance with the direction of the direct current, and the second switch module 14 is closed when receiving the first control signal, at this time, the dc current suppression device stops operating, and in a loop, the direct current and the alternating current may flow through the line of the second switch module 14.
When the current detection module 11 detects that the direct current is greater than or equal to the preset current threshold, the current detection module 11 sends a second control signal to the pulse trigger control module 12 and the second switch module 14. The pulse trigger control module 12 starts to operate when receiving the second control signal, that is, a trigger pulse is sent out according to a certain frequency so as to close or open the power electronic switch S1 in the first switch module, which is consistent with the flow direction of the direct current, and the second switch module 14 is opened when receiving the second control signal, at this time, the suppression device for the direct current starts to operate, in a loop, when the switch S1 is closed, the direct current flows through the line of the switch S1, and when the switch S1 is opened, the direct current stops flowing. Through the repeated on-off of the control switch S1, the direct current is controlled at a lower level under the inhibition of the inductance of the access equipment, so that the normal operation of the access equipment is ensured, and the service life of the equipment is prolonged.
It can be understood that the preset current threshold may be a fixed current threshold set according to human experience and suitable for various access devices, or may be a dynamic current threshold adjusted according to actual access devices, which does not affect the beneficial effects obtained by the present invention.
In a preferred embodiment, the frequency of the trigger pulse sent by the pulse trigger control module 12 is set appropriately, so that the switch S1 is closed when the alternating current and the direct current in the loop are in the same direction, and is opened when the alternating current and the direct current in the loop are in the opposite direction, thereby ensuring that a path is provided for the alternating current in the loop at any time.
Specifically, referring to fig. 4, it is a schematic flowchart of the start-up operation of the pulse trigger control module in the dc current suppression device according to the first embodiment of the present invention. When the pulse trigger control module is started to work, the pulse trigger control module sends out a trigger pulse to control the on-off of a power electronic switch consistent with the direct current flow direction in the first switch module, and the method specifically comprises the following steps of S21-S22:
and S21, when the pulse trigger control module is started to work, sending a trigger pulse every other first preset time to close the power electronic switch consistent with the direct current flow direction.
And S22, after a second preset time period, stopping sending the trigger pulse by the pulse trigger control module so as to disconnect the power electronic switch consistent with the direct current flow direction.
The second preset time length is less than the first preset time length; the first preset time is the direction change period of alternating current on the loop; the second preset time length is the time length that the alternating current and the direct current are in the same direction in the direction change period.
The direction change of the alternating current in the loop has periodicity, and in the embodiment of the invention, the direction change period of the alternating current is set as a first preset time period T1, and the time period of the direction change period in which the alternating current and the direct current are in the same direction is set as a second preset time period T2.
When the current detection module 11 detects that the direct current is greater than or equal to the preset current threshold, further detecting the directions of the alternating current and the direct current on the loop, and when it is determined that the alternating current and the direct current are in the same direction, sending the second control signal. The second switch module 14 is turned off when receiving the second control signal, and the pulse trigger control module 12 starts to operate when receiving the second control signal, that is, continuously sends out a trigger pulse to close the power electronic switch S1 in accordance with the dc current flow direction, and stops sending out the trigger pulse after a second preset time period T2 elapses, so that the power electronic switch S1 in accordance with the dc current flow direction is turned off after the trigger pulse is lost. With the first preset time period T1 as a period, the pulse trigger control module 12 completes one time of sending a trigger pulse and stopping the trigger pulse to control the switch S1 to be turned on and off repeatedly.
In one embodiment, the direction change period of the alternating current in the electric power system in China is 20ms, namely, the frequency of 50Hz, so that the first preset time period T1 can be set to 20ms, and the second preset time period T2 can be set to 10 ms.
By adopting the technical scheme of the embodiment of the invention, in the loop, when the alternating current and the direct current are in the same direction, the switch S1 is just closed, so that the alternating current and the direct current in the loop can both flow, and the direct current can be slowly increased under the inhibition of the inductance in the equipment; when the alternating current and the direct current are in opposite directions, the switch S1 is switched off, so that the direct current in the loop is cut off, and the alternating current can flow through the normally closed switch S2 which is in inverse parallel connection with the switch S1, so that the direct current in the loop is restrained at a lower level, and meanwhile, the beneficial effect of providing a path for the alternating current in the loop at any time is ensured, so that the normal operation of access equipment is ensured, and the service life of the equipment is prolonged.
The device for suppressing direct current provided by the embodiment of the invention is used for being connected into a device circuit with an inductance module and needing to suppress direct current. Through controlling the repeated on-off of the first switch module, the inductance module in the equipment is utilized to inhibit the rising rate of the direct current in the loop and prolong the time for the direct current to reach a stable value, so that the direct current entering the ground is inhibited at a lower level, the phenomenon that the overlarge direct current enters the ground and influences the normal operation of peripheral equipment flowing into the ground is effectively avoided, meanwhile, a path is provided for the alternating current in the loop at all times, the safe operation of the equipment is ensured, and the service life of the equipment is prolonged. In addition, the suppression device for the direct current has a simple structure, and can effectively save installation space and manufacturing cost.
Fig. 5 is a schematic structural diagram of another dc current suppressing apparatus according to the second embodiment of the present invention. Another dc current suppressing apparatus 20 according to a second embodiment of the present invention is the dc current suppressing apparatus according to the first embodiment, including: the device comprises a current detection module 11, a pulse trigger control module 12, a first switch module 13 and a second switch module 14; wherein the first switch module 13 comprises a set of anti-parallel power electronic switches S1 and S2. Further comprising: an inductance module 21 and a resistance module 22.
The inductance module 21 and the resistance module 22 are connected in series with the first switch module 13 and then connected in parallel with the second switch module 14, and the parallel circuit is connected in series with the current detection module 11; the pulse trigger control module 12 is connected to the first switch module 13.
The current detection module 11 is used for detecting the current magnitude and the current direction on the loop; and sending out a control signal to control the working state of the pulse trigger control module 12 and the on-off of the second switch module 14 according to the current magnitude and the current direction.
The pulse trigger control module 12 is configured to send a trigger pulse to control on/off of a power electronic switch in the first switch module 13, which is consistent with a direct current flow direction, when the power electronic switch is started to operate.
When the direct current flows into the ground, normal operation of the peripheral equipment at the entry point is affected. For example, when an in-ground direct current flows into pipelines around a direct current inflow site, such as oil and gas pipelines, and a ground grid in a surrounding substation, the corrosion and damage of the pipelines are aggravated by an excessive direct current due to the influence of the direct current; when the direct current flows into the current transformer and the voltage transformer, the magnetic flux distribution in the current transformer and the voltage transformer is changed, so that the measurement error of the current and the voltage is increased, and the correct action of the relay protection device is further influenced.
In order to solve the above technical problem, the dc current suppressing device 20 provided in the second embodiment of the present invention is used to be connected to an equipment circuit without an inductance module, for example, pipelines such as oil and natural gas mentioned in the above scenario, or electrical equipment such as a transformer substation grounding grid, a current transformer, and a voltage transformer, so as to suppress the magnitude of the dc current, reduce corrosion to the oil and natural gas pipelines, reduce corrosion to the grounding grid, and reduce the effect of measurement errors of the current transformer and the voltage transformer.
The dc current suppressing apparatus 20 according to the second embodiment of the present invention includes all the functional modules of the dc current suppressing apparatus 10 according to the first embodiment, and the device structure and the implementation manner of each functional module are similar to or the same as those of the first embodiment. On this basis, the dc current suppressing device 20 further includes an inductance module 21 and a resistance module 22. Since the suppression device 20 for dc current according to the embodiment of the present invention is used to be connected to a device circuit without an inductance module, the suppression effect on dc current is achieved by the inductance module 21 during the suppression of dc current.
Preferably, the inductance of the inductance module 21 is much larger than the resistance of the resistance module 22.
It can be understood that the above-mentioned use scenarios of pipelines such as oil and gas, current transformers, voltage transformers, etc. are only examples, and in the practical application process, the dc current suppression apparatus 20 may be applied to other devices that do not have an inductance module or need an additional inductance module to achieve the suppression effect on the dc current according to the needs of the practical situation, without affecting the beneficial effects of the present invention.
It can be understood that the working principle of the dc current suppression device 20 according to the second embodiment of the present invention is the same as that of the dc current suppression device 10 according to the first embodiment, and all the implementation processes of the dc current suppression device 10 according to the first embodiment are included, and are not described herein again.
The device for suppressing direct current provided by the second embodiment of the invention is used for being connected to an equipment circuit without an inductance module and needing to suppress direct current. Through controlling the repeated on-off of the first switch module, the inductance module arranged in the suppression device is utilized to suppress the rising rate of the direct current in the loop and prolong the time for the direct current to reach a stable value, so that the direct current entering the ground is suppressed at a lower level, the phenomenon that the overlarge direct current enters the ground is effectively avoided, the influence on the normal operation of peripheral equipment flowing into the ground is caused, meanwhile, a channel is provided for the alternating current in the loop at all times, the safe operation of the equipment is ensured, and the service life of the equipment is prolonged. In addition, the suppression device for the direct current has a simple structure, and can effectively save installation space and manufacturing cost.
Fig. 6 is a schematic structural diagram of a dc current suppression device according to a third preferred embodiment of the present invention. The dc current suppression device 30 according to the third embodiment of the present invention, on the basis of the first or second embodiment, further includes: a third switch module 31; the third switching module 31 is connected in series with the first switching module 13.
Further, the first control signal sent by the current detection module 11 is also used for controlling the third switching module 31 to be turned off; the second control signal is also used to control the third switching module 31 to close.
In the embodiment of the present invention, a third switch module 31 is connected in series with the line of the first switch module. When the suppression device for the direct current needs to be overhauled, the third switch module 31 is controlled to be switched off, so that the suppression device 30 for the direct current is ensured to be in a power-off state, and a safety effect is achieved. In addition, the third switch module 31 can also play a role in preventing false conduction, and the first switch module is prevented from being conducted by mistake when the suppression device is not connected with the equipment, so that the safe use of the suppression device is prevented from being influenced.
Preferably, the dc current suppressing device 30 further includes a circuit protection module 32. The circuit protection module 32 is connected in parallel with the first switch module 13, and is configured to protect the first switch module 13 from breakdown.
The circuit protection module 32 may be one of a protection gap, an RC resistance-capacitance loop and a lightning arrester, or other circuit protection modules with the same protection function, and the beneficial effects of the invention are not affected.
More preferably, a delayed exit time T3 of the dc current suppression device may be further set, and when the dc current detected by the current detection module 11 is smaller than the preset current threshold, after a time T3 elapses, the first control signal is sent, the second switch module is closed, the pulse control module is triggered to stop sending the pulse to turn off the first switch module, and turn off the third switch module, at this time, the dc current suppression device exits from operation.
It can be understood that the working principle of the dc current suppression device 30 according to the third embodiment of the present invention is the same as that of the dc current suppression device according to the first embodiment or the second embodiment, and all the implementation processes of the dc current suppression device according to the first embodiment or the second embodiment are included, and are not described herein again.
The third embodiment of the invention provides a direct current suppression device, which is used for being connected into a device circuit needing to suppress direct current. The repeated on-off of the first switch module is controlled, the inductance module in the equipment or the inductance module arranged in the suppression device of the direct current is utilized to suppress the rising rate of the direct current in the loop and prolong the time of the direct current reaching a stable value, so that the direct current entering the ground is suppressed at a lower level, the influence of the overlarge direct current entering the ground on the normal operation of peripheral equipment flowing into the ground is effectively avoided, and meanwhile, a path is provided for the alternating current in the loop at all times, so that the safe operation of the equipment is ensured, and the service life of the equipment is prolonged. In addition, the suppression device for the direct current is also provided with a switch module and a circuit protection device for preventing misconduction, so that the safe operation of the equipment circuit can be effectively ensured. The device has simple structure, and can effectively save the installation space and the manufacturing cost.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A device for suppressing a direct current, comprising: the device comprises a current detection module, a pulse trigger control module, a first switch module and a second switch module; wherein the first switch module comprises a set of power electronic switches connected in anti-parallel;
the first switch module is connected with the second switch module in parallel and then connected with the current detection module in series; the pulse trigger control module is connected with the first switch module;
the current detection module is used for detecting the current magnitude and the current direction on the loop; sending a control signal to control the working state of the pulse trigger control module and the on-off of the second switch module according to the current magnitude and the current direction;
the pulse trigger control module is used for sending a trigger pulse to control the on-off of a power electronic switch which is consistent with the flow direction of the direct current in the first switch module when the first switch module is started to work.
2. The dc current suppression device according to claim 1, further comprising an inductance module and a resistance module;
and the inductance module is connected with the first switch module in series after being connected with the resistance module in series.
3. The apparatus according to claim 1 or 2, wherein the control signal sent by the current detection module comprises a first control signal and a second control signal;
the first control signal is used for controlling the pulse trigger control module to stop working and controlling the second switch module to be closed;
the second control signal is used for controlling the pulse trigger control module to start and work and controlling the second switch module to be switched off.
4. The dc current suppressing apparatus according to claim 3, wherein the current detecting module detects a magnitude and a direction of a current flowing through the loop; and according to the current magnitude and the current direction, sending a control signal to control the working state of the pulse trigger control module and the on-off of the second switch module specifically comprises:
the current detection module detects the magnitude of direct current on a loop;
when the direct current on the loop is judged to be smaller than a preset current threshold value, the first control signal is sent out;
when the direct current is judged to be larger than or equal to the preset current threshold value, the directions of the alternating current and the direct current on the loop are detected, and when the alternating current and the direct current are judged to be in the same direction, the second control signal is sent.
5. The dc current suppressing apparatus according to claim 4, wherein the pulse trigger control module, when activated, sends out a trigger pulse to control on/off of a power electronic switch in the first switch module, which is in accordance with a dc current flowing direction, and specifically includes:
after the pulse trigger control module is started to work, sending trigger pulses every other first preset time to close the power electronic switch consistent with the direct current flow direction;
after a second preset time, stopping sending a trigger pulse by the pulse trigger control module so as to disconnect the power electronic switch consistent with the direct current flow direction;
the second preset time length is less than the first preset time length; the first preset time is the direction change period of alternating current on the loop; the second preset time length is the time length that the alternating current and the direct current are in the same direction in the direction change period.
6. The dc current suppression device according to claim 3, further comprising a third switching module; the third switch module is connected in series with the first switch module.
7. The dc current suppressing apparatus according to claim 6, wherein the first control signal is further used to control the third switching module to be turned off; the second control signal is also used to control the third switch module to close.
8. The suppression apparatus for direct current according to claim 1 or 2, further comprising a circuit protection module;
the circuit protection module is connected with the first switch module in parallel and used for protecting the first switch module from being broken down.
9. The dc current suppression device of claim 8, wherein said circuit protection module comprises but is not limited to a protection gap, an RC.
10. The dc current suppressing apparatus according to claim 1 or 2, wherein the power electronic switch in the first switch module is a thyristor or an IGBT power electronic switch.
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