CN113690862A - Device and method for eliminating overvoltage in flexible direct current system - Google Patents
Device and method for eliminating overvoltage in flexible direct current system Download PDFInfo
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- CN113690862A CN113690862A CN202110970587.9A CN202110970587A CN113690862A CN 113690862 A CN113690862 A CN 113690862A CN 202110970587 A CN202110970587 A CN 202110970587A CN 113690862 A CN113690862 A CN 113690862A
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- direct current
- switch
- overvoltage
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- grounding switch
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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
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for DC systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/202—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage for DC systems
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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
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device
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Abstract
本申请公开了一种消除柔性直流系统中过电压的装置及方法，其中装置包括：控制模块、隔离开关、接地开关、放电电阻；隔离开关的第一端连接于直流断路器的第一端，隔离开关的第二端连接于接地开关的第一端，接地开关的第二端连接于放电电阻的第一端，放电电阻的第二端接地；控制模块，用于当柔性直流系统中产生过电压时，控制隔离开关断开后，并控制接地开关闭合使得直流线路上储存的能量通过放电电阻进行释放，直至柔性直流系统中的线路电压降低为预置电压值断开接地开关，并控制隔离开关闭合。从而解决了现有技术忽略了针对直流断路器动作导致系统电缆的持续过电压的技术问题。
The present application discloses a device and method for eliminating overvoltage in a flexible DC system, wherein the device includes: a control module, an isolation switch, a grounding switch, and a discharge resistor; the first end of the isolation switch is connected to the first end of the DC circuit breaker, The second end of the isolating switch is connected to the first end of the grounding switch, the second end of the grounding switch is connected to the first end of the discharge resistor, and the second end of the discharge resistor is grounded; the control module is used to When the voltage is high, after the control isolation switch is turned off, and the grounding switch is controlled to close, so that the energy stored on the DC line is released through the discharge resistance, until the line voltage in the flexible DC system is reduced to the preset voltage value, disconnect the grounding switch, and control the isolation The switch is closed. Thus, the technical problem that the prior art ignores the continuous overvoltage of the system cable caused by the action of the DC circuit breaker is solved.
Description
Technical Field
The present application relates to the field of power technologies, and in particular, to a device and a method for eliminating overvoltage in a flexible dc system.
Background
In recent years, direct current transmission has received more and more attention and research by virtue of its easy access to renewable energy. The flexible direct-current power transmission system based on the voltage source converter becomes an important technical means for solving the problems of large-scale grid connection of renewable energy sources, island power transmission and the like by virtue of the advantages of low manufacturing difficulty, high waveform quality, strong fault handling capacity and the like.
The direct current circuit breaker can clear short-circuit current, isolate faults, avoid expansion of a fault range and improve power supply reliability, and is a key of a flexible direct current power transmission system network. At the instant of breaking the current, however, a larger voltage is present across the dc breaker. Direct current breaker terminal voltage can superpose with system voltage, the problem of overvoltage appears, and the overvoltage can charge to direct current circuit, raises direct current circuit's voltage, and when the both ends direct current breaker of fault point circuit all break back, overvoltage duration is of a specified duration on the unsettled circuit, and harm is big.
At present, the research on the operation overvoltage of the direct current circuit breaker is very little, and the existing overvoltage protection scheme mainly aims at the overvoltage caused by the fault of the flexible direct current transmission system. The overvoltage duration that flexible direct current system trouble caused is short, can not appear lasting overvoltage in the circuit, and the overvoltage that system self trouble leads to is restricted mainly to current scheme through the mode of arranging the arrester, does not have the lasting overvoltage protection scheme that leads to the system cable to direct current breaker action.
Therefore, it is an urgent need to solve the above-mentioned problems by those skilled in the art to provide a technical solution for eliminating the overvoltage during the operation of the dc circuit breaker in the flexible dc system.
Disclosure of Invention
The application provides a device and a method for eliminating operation overvoltage in a flexible direct current system, which are used for solving the technical problem that continuous overvoltage of a system cable caused by action of a direct current breaker is neglected in the prior art.
In view of the above, the present application provides, in a first aspect, an apparatus for eliminating overvoltage in a flexible dc system, the apparatus including:
the device comprises a control module, an isolating switch, a grounding switch and a discharge resistor;
the first end of the isolating switch is connected to the first end of the direct current breaker, the second end of the isolating switch is connected to the first end of the grounding switch, the second end of the grounding switch is connected to the first end of the discharging resistor, and the second end of the discharging resistor is grounded;
and the control module is used for controlling the disconnecting switch to be disconnected and then controlling the grounding switch to be closed to discharge the discharge resistor when overvoltage is generated in the flexible direct current system, and disconnecting the grounding switch until the line voltage in the flexible direct current system is reduced to a preset voltage value and controlling the disconnecting switch to be closed.
Optionally, the isolation switch is: a fast disconnecting switch.
Optionally, the grounding switch is: a fast grounding switch.
Optionally, the second end of the dc breaker is connected to the dc side of the converter station.
Optionally, the ac side of the converter station is connected to an ac system via a coupling transformer.
In a second aspect of the present application, there is provided a method for eliminating overvoltage in a flexible dc system, which is applied to the apparatus for eliminating overvoltage in a flexible dc system provided in the first aspect, and the method includes:
when overvoltage is generated in the flexible direct current system, the control module controls the disconnecting switch to be disconnected and controls the grounding switch to be closed, so that energy stored in the direct current circuit is released through the discharging resistor until the voltage of the circuit in the flexible direct current system is reduced to a preset voltage value, the grounding switch is disconnected, and the disconnecting switch is controlled to be closed.
According to the technical scheme, the method has the following advantages:
the application provides a device for eliminating overvoltage in a flexible direct current system, which comprises: the device comprises a control module, an isolating switch, a grounding switch and a discharge resistor; the first end of the isolating switch is connected to the first end of the direct current breaker, the second end of the isolating switch is connected to the first end of the grounding switch, the second end of the grounding switch is connected to the first end of the discharging resistor, and the second end of the discharging resistor is grounded; and the control module is used for controlling the disconnecting of the isolating switch and controlling the grounding switch to be closed after the disconnecting switch is switched off when overvoltage is generated in the flexible direct current system, so that the energy stored on the direct current line is released through the discharging resistor until the line voltage in the flexible direct current system is reduced to a preset voltage value, and then the grounding switch is switched off and controlled to be closed. Therefore, long-time overvoltage caused by action of the direct current breaker on a line in the flexible direct current system is eliminated. Compared with the prior art that the overvoltage caused by the fault of the flexible direct current system is only aimed at, the duration of the overvoltage is short, the overvoltage is limited in a mode of configuring the lightning arrester, and the overvoltage caused by the action of the direct current breaker is not considered, the overvoltage caused by the action of the direct current breaker is considered.
Drawings
Fig. 1 is a schematic diagram of a flexible dc power grid architecture for installing an overvoltage protection device in a flexible dc system according to an embodiment of the present application;
fig. 2 is a schematic flowchart of a method for eliminating overvoltage in a flexible dc system according to an embodiment of the present disclosure.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.
Referring to fig. 1, fig. 1 is a schematic diagram of a flexible dc power grid structure for installing and eliminating an overvoltage device in a flexible dc system according to an embodiment of the present application.
The device for eliminating overvoltage in the flexible direct current system provided by the embodiment of the application comprises: control module, isolator, earthing switch, discharge resistor.
The first end of the isolating switch is connected to the first end of the direct current breaker, the second end of the isolating switch is connected to the first end of the grounding switch, the second end of the grounding switch is connected to the first end of the discharging resistor, and the second end of the discharging resistor is grounded.
And the control module is used for controlling the disconnecting of the isolating switch and controlling the grounding switch to be closed after the disconnecting switch is switched off when overvoltage is generated in the flexible direct current system, so that the energy stored on the direct current line is released through the discharging resistor until the line voltage in the flexible direct current system is reduced to a preset voltage value, and then the grounding switch is switched off and controlled to be closed.
It should be noted that, in order to improve the response speed of the cancellation device, the isolator of the present application selects a fast isolator, and the grounding switch selects a fast grounding switch.
The following is an example of the application of the device of the present application to a flexible direct current grid:
as shown in fig. 1, VSCs 1 to VSC4 are four converter stations in a flexible direct current power grid, CB12, CB21 to CB43 and the like are all dc breakers, R is a discharge resistor, S is a fast grounding switch, and BPD is a fast disconnecting switch.
The flexible direct current system comprises four converter stations, a plurality of direct current breakers and a plurality of direct current lines. The direct current system adopts a pseudo-bipolar structure, and each converter station only comprises one converter valve. The converter stations are connected through cables to form a ring structure. The converter station AC measurement is connected with the AC system through a connecting transformer, and the positive and negative ends of each line on the DC side are provided with DC breakers which can be a mechanical DC breaker, a hybrid DC breaker and a coupling negative pressure breaker.
Taking CB12 and CB21 as examples, the action sequence scheme proposed by the present application is as follows:
after the direct current circuit breakers CB1 and CB2 act, the voltage of a line is the voltage superposed by the system voltage and the voltage of the direct current circuit breaker terminal, the line is suspended, and the direct current system protection can be triggered to cause the converter valve to be locked if the overvoltage lasts for a long time.
Considering that the direct current circuit breaker may not be provided with a backup circuit breaker, in order to ensure that the direct current line is isolated from the system when the grounding switch is disconnected, the two ends of the line are provided with quick isolating switches, and when overvoltage is generated in the flexible direct current system, the quick isolating switches BPD are rapidly disconnected to isolate the direct current line.
After the quick isolating switch is disconnected, the grounding switch S of the direct current line is closed, the energy on the direct current line is released through the discharging resistor R, and the direct current voltage on the direct current line is rapidly reduced.
When the voltage on the direct current line is reduced to a preset voltage value, the grounding switch S is disconnected, the rapid isolating switch BPD is turned off, and the overvoltage eliminating operation is completed.
By adopting the method, the line overvoltage caused by the on-off of the direct current breaker can be rapidly eliminated.
The application provides an eliminate device of overvoltage among flexible direct current system, with the overvoltage that the current only caused to flexible direct current system trouble itself, and overvoltage duration is short, limits the overvoltage through the mode of configuration arrester, does not consider the operation overvoltage's that direct current breaker action leads to technical scheme to compare, the overvoltage that direct current breaker action leads to has been considered in this application. Therefore, the technical problem that continuous overvoltage of a system cable is caused by action of a direct-current breaker in the prior art is solved.
The above is a device for eliminating overvoltage in a flexible direct current system provided by the embodiments of the present application, and the following is a method for eliminating overvoltage in a flexible direct current system provided by the embodiments of the present application.
Referring to fig. 2, fig. 2 is a schematic flowchart illustrating a method for eliminating overvoltage in a flexible dc system according to an embodiment of the present disclosure.
The method for eliminating the overvoltage in the flexible direct current system provided by the embodiment of the application comprises the following steps:
when overvoltage is generated in the flexible direct current system, the control module controls the disconnecting switch to be disconnected and controls the grounding switch to be closed, so that energy stored in the direct current circuit is released through the discharging resistor until the voltage of the circuit in the flexible direct current system is reduced to a preset voltage value, the grounding switch is disconnected, and the disconnecting switch is controlled to be closed.
It should be noted that, the method provided by this embodiment is applied to the flexible dc power grid of the above device embodiment, and may be understood as the following steps:
1) and after the flexible direct current power grid fails, the direct current circuit breakers at two ends of the fault circuit act.
2) After the direct current breaker acts, high voltage is generated at two ends of the direct current breaker and is superposed with system voltage to generate overvoltage on a circuit.
3) After overvoltage occurs on the circuit, the quick isolating switches at two ends of the circuit are disconnected, and the fault circuit is ensured to be isolated from the converter valve.
4) The grounding switch is closed, so that the direct current circuit is grounded through the discharging resistor, the energy stored on the direct current cable is released, and the overvoltage is rapidly reduced.
5) When the line voltage is reduced to a preset voltage value, the grounding switch is disconnected, and the quick isolating switches at the two ends of the line are closed.
The terms "first," "second," "third," "fourth," and the like in the description of the application and the above-described figures, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (6)
1. An apparatus for eliminating overvoltage in a flexible dc system, comprising: the device comprises a control module, an isolating switch, a grounding switch and a discharge resistor;
the first end of the isolating switch is connected to the first end of the direct current breaker, the second end of the isolating switch is connected to the first end of the grounding switch, the second end of the grounding switch is connected to the first end of the discharging resistor, and the second end of the discharging resistor is grounded;
and the control module is used for controlling the disconnecting switch to be disconnected and then controlling the grounding switch to be closed to discharge the discharge resistor when overvoltage is generated in the flexible direct current system, and disconnecting the grounding switch until the line voltage in the flexible direct current system is reduced to a preset voltage value and controlling the disconnecting switch to be closed.
2. The apparatus for eliminating overvoltage in a flexible DC system according to claim 1, wherein said isolation switch is: a fast disconnecting switch.
3. The apparatus for eliminating overvoltage in a flexible dc system according to claim 1, wherein said grounding switch is: a fast grounding switch.
4. An arrangement for eliminating overvoltages in flexible dc systems according to claim 1, characterized in that the second end of said dc breaker is connected to the dc side of the converter station.
5. An arrangement for eliminating overvoltages in flexible dc systems according to claim 4, characterized in that the ac side of the converter station is connected to the ac system via a coupling transformer.
6. A method for eliminating overvoltage in a flexible direct current system, which is applied to the device for eliminating overvoltage in the flexible direct current system of any one of claims 1 to 5, the method comprising:
when overvoltage is generated in the flexible direct current system, the control module controls the disconnecting switch to be disconnected and controls the grounding switch to be closed, so that energy stored in the direct current circuit is released through the discharging resistor until the voltage of the circuit in the flexible direct current system is reduced to a preset voltage value, the grounding switch is disconnected, and the disconnecting switch is controlled to be closed.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110970587.9A CN113690862A (en) | 2021-08-23 | 2021-08-23 | Device and method for eliminating overvoltage in flexible direct current system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110970587.9A CN113690862A (en) | 2021-08-23 | 2021-08-23 | Device and method for eliminating overvoltage in flexible direct current system |
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| WO2020233180A1 (en) * | 2019-05-21 | 2020-11-26 | 南京南瑞继保电气有限公司 | Current-limiting controllable lightning arrester, converter, power transmission system, and control method |
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2021
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05111119A (en) * | 1991-10-15 | 1993-04-30 | Toshiba Corp | Gas insulation switching device |
| EP2568480A2 (en) * | 2011-09-08 | 2013-03-13 | PHOENIX CONTACT GmbH & Co. KG | Overvoltage protection device |
| US20190006838A1 (en) * | 2016-07-20 | 2019-01-03 | Global Energy Interconnection Research Institute Co., Ltd | Novel combined direct current circuit breaker and application method thereof |
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