CN114389234A - Ground fault protection system of flexible direct current power grid and protection control method thereof - Google Patents

Ground fault protection system of flexible direct current power grid and protection control method thereof Download PDF

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Publication number
CN114389234A
CN114389234A CN202111679371.3A CN202111679371A CN114389234A CN 114389234 A CN114389234 A CN 114389234A CN 202111679371 A CN202111679371 A CN 202111679371A CN 114389234 A CN114389234 A CN 114389234A
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CN
China
Prior art keywords
ground fault
control device
protection
power grid
fault
Prior art date
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Pending
Application number
CN202111679371.3A
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Chinese (zh)
Inventor
滕孟锋
李振动
安海清
刘靖国
金海望
田凯哲
李金卜
张晓飞
李涛
柳杨
赵凯曼
高宏达
刘宪辉
董海飞
翟永尚
岳娜
穆凌杰
李泠萱
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
State Grid Jibei Electric Power Co Ltd Beijing Ultra High Voltage Co
State Grid Corp of China SGCC
Original Assignee
State Grid Jibei Electric Power Co Ltd Beijing Ultra High Voltage Co
State Grid Corp of China SGCC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by State Grid Jibei Electric Power Co Ltd Beijing Ultra High Voltage Co, State Grid Corp of China SGCC filed Critical State Grid Jibei Electric Power Co Ltd Beijing Ultra High Voltage Co
Priority to CN202111679371.3A priority Critical patent/CN114389234A/en
Publication of CN114389234A publication Critical patent/CN114389234A/en
Pending legal-status Critical Current

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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
    • H02H3/16—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 fault current to earth, frame or mass
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00032—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for
    • H02J13/00036—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for the elements or equipment being or involving switches, relays or circuit breakers
    • H02J13/0004—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for the elements or equipment being or involving switches, relays or circuit breakers involved in a protection system
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/20—Systems supporting electrical power generation, transmission or distribution using protection elements, arrangements or systems

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Direct Current Feeding And Distribution (AREA)

Abstract

The application discloses a ground fault protection system of a flexible direct current power grid metal return wire and a protection control method thereof. The auxiliary protection device is used for monitoring the ground fault of a metal return line layer of the flexible direct-current power grid, and sending a ground fault signal to the upper control device when the metal return line layer has the ground fault; the main protection device is used for calculating differential current according to the current of the station and the current on the opposite side of the metal return line layer, and controlling a direct current change-over switch of the metal return line layer to perform protection control according to the differential current. Therefore, the flexible direct-current power grid is protected, and the safe operation of the flexible direct-current power grid is guaranteed.

Description

Ground fault protection system of flexible direct current power grid and protection control method thereof
Technical Field
The application relates to the technical field of direct current transmission, in particular to a ground fault protection system of a metal return wire of a flexible direct current power grid and a protection control method thereof.
Background
Renewable energy sources such as wind energy, solar energy and the like generate electricity intermittently and uncertainties, so that the traditional alternating current power grid cannot be normally consumed. The flexible direct-current power grid can flexibly control active power and reactive power and supply power to a weak alternating-current system, can realize bidirectional power transmission, achieves reasonable power distribution, and becomes the optimal choice for solving new energy power generation grid connection at present.
When a direct-current cable scheme with high voltage and high current capacity is adopted, the flexible direct-current power grid is poor in economical efficiency due to high cost, and therefore the scheme is generally realized by adopting an outdoor overhead line scheme. When the metal return wire layer of the flexible direct current power grid running on the overhead line has a ground fault, the fault ground point normally in bipolar balanced running does not have fault current, the protection does not act at the moment, the metal return wire layer is in a fault ground running state for a long time, and the system runs in a direct ground mode. At this time, if the valve-side connecting line has a ground fault, the converter valve may be directly short-circuited, and power electronics of the converter valve may be burned out. Therefore, it is necessary to identify and execute a protection action in time when a ground fault occurs on a metal return layer of the flexible dc power grid, so as to ensure safe operation of the flexible dc power grid.
Disclosure of Invention
In view of this, the present application provides an earth fault protection system for a metal return line of a flexible dc power grid and a protection control method thereof, which are used for monitoring an earth fault of the metal return line to ensure safe operation of the flexible dc power grid.
In order to achieve the above object, the following solutions are proposed:
the utility model provides a ground fault protection system of flexible direct current electric wire netting metallic return, ground fault protection system includes upper control device, still include respectively with upper control device signal connection's utmost point controlling means, main protection device and supplementary protection device, wherein:
the upper layer control device is used for receiving control instruction parameters of the pole control device, protection action signals of the main protection device and ground fault signals of the auxiliary control device and sending operation control instructions to the pole control device;
the pole control device is arranged in a converter station of the flexible direct-current power grid and used for controlling a control mode, a line state and a converter valve state of the converter station based on the operation control instruction;
the auxiliary protection device is used for monitoring the ground fault of the metal return line layer of the flexible direct-current power grid, and sending a ground fault signal to the upper control device when the metal return line layer has the ground fault;
the main protection device is used for calculating a differential current according to the current of the station and the current on the opposite side of the metal return wire layer, controlling a direct current change-over switch of the metal return wire layer to perform protection control according to the differential current, and sending a protection action signal to the upper control device.
Optionally, the auxiliary protection device includes a ground resistance impedance monitoring device and a metal return monitoring device.
Optionally, the ground resistance impedance monitoring device is configured to dynamically monitor the impedance of the ground resistance of the metal return line layer, and is configured to identify a ground fault of the ground resistance, generate the ground fault signal based on the ground fault, and send the ground fault signal to the upper control device.
Optionally, the metal return line monitoring device is configured to generate a ground fault signal based on a ground fault of the metal return line layer, and send the ground fault signal to the upper control device.
Optionally, the flexible dc power grid includes a positive electrode running layer, a metal return line layer, and a negative electrode running layer, wherein:
the metal return wire layer is composed of a neutral bus and a metal return wire and is grounded through a grounding resistor.
Optionally, the metal return line layer is provided with the grounding resistor grounding point at least two converter stations in the flexible direct current power grid.
A protection control method applied to the ground fault protection system of the flexible dc power grid metallic return wire is characterized in that the protection control method comprises the following steps:
when the metal return line layer has a ground fault, the main protection device controls the direct current change-over switch to execute a protection action based on the differential current;
when the metal return layer has a ground fault, the auxiliary protection device sends an alarm message to the upper control device, and if the upper control device does not receive an action signal of the main protection device, the pole control device executes a preset power adjustment action and a ground station transfer action.
Optionally, the preset power adjusting action includes the steps of:
if the fault converter station with the ground fault is in a non-island operation mode and the converter of the fault converter station is in an active power control mode, sending the alarm information to the upper control device so that the upper control device can adjust the fault converter station in the flexible direct current power grid into a bipolar imbalance mode;
if the fault converter station is in a non-island operation mode and a converter of the fault converter station is in a fixed direct-current voltage control mode, sending the alarm information to the upper control device so that the upper control device can adjust other converter stations in the fixed active power mode in the flexible direct-current power grid to be in a bipolar unbalanced operation mode;
and if the fault converter station is in an island operation mode, namely a converter of the fault converter station is in an alternating current voltage control mode, transmitting the alarm information to the upper control device so that the upper control device adjusts other converter stations in the fixed active power mode in the flexible direct current network into a bipolar unbalanced operation mode.
Optionally, the preset ground station transferring action includes the steps of:
and the upper control device controls the converter station with the grounding point to carry out grounding point transfer, namely, standby grounding points of other converter stations are closed, and the current grounding point is pulled.
According to the technical scheme, the ground fault protection system comprises an upper layer control device, a pole control device, a main protection device and an auxiliary protection device, wherein the pole control device, the main protection device and the auxiliary protection device are in signal connection with the upper layer control device. The auxiliary protection device is used for monitoring the ground fault of a metal return line layer of the flexible direct-current power grid, and sending a ground fault signal to the upper control device when the metal return line layer has the ground fault; and the main protection device calculates the differential current according to the current of the station and the current on the opposite side of the metal return wire layer, and controls the direct current change-over switch of the metal return wire layer to perform protection control according to the differential current. Therefore, the flexible direct-current power grid is protected, and the safe operation of the flexible direct-current power grid is guaranteed.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a block diagram of a ground fault protection system of a flexible dc power grid according to an embodiment of the present application;
fig. 2 is a schematic diagram of a flexible dc power grid.
Detailed Description
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.
Example one
Fig. 1 is a block diagram of a ground fault protection system of a flexible dc power grid according to an embodiment of the present application.
As shown in fig. 1, the ground fault protection system provided in this embodiment is used for ground fault protection of a metal return wire of a flexible dc power grid, and specifically includes an upper control device 10, a pole control device 20, a main protection device 30, and an auxiliary protection device 40, where the upper control device is in signal connection with the pole control device, the main protection device, and the auxiliary protection device respectively through a signal line or a network.
The flexible direct-current power grid comprises a positive electrode running layer, a metal return wire layer and a negative electrode running layer, wherein a grounding resistor is connected with the metal return wire layer through a grounding change-over switch, and the metal return wire layer is grounded through the grounding resistor.
At least one converter station in the flexible direct current power grid is set to be in a fixed direct current voltage control mode and used for maintaining the voltage stability of the flexible direct current power grid, and other converter stations are set to be in a fixed active power control mode. And when the sending end converter station operates in an isolated island mode, the sending end converter station is set to be in a constant alternating voltage control mode.
The upper control device is specifically used for controlling the whole flexible direct current power grid, the flexible direct current power grid comprises a plurality of converter stations, and each converter station is provided with a corresponding pole control device, a main protection device and an auxiliary protection device. In a flexible converter station, grounding resistance grounding points are arranged at least at two converter stations.
The upper layer control device is used for communicating and interacting with the pole control devices of the converter stations, mainly used for receiving control modes, line states and converter valve states of the pole control devices of the converter stations, protection action signals of the main protection device and ground fault signals of the auxiliary control device, and also used for sending control modes and control instruction information to the converter stations to optimize and adjust the operation modes of the converter stations of the flexible direct current power grid.
The pole control device is mainly used for selecting a control mode of each converter station in the flexible direct current power grid and communicating with the upper layer control device. In the flexible direct current power grid converter station, an active control mode has a constant direct current voltage control function and a constant active power control function, and an island converter station also has a constant frequency control function; the reactive control mode has a constant reactive power control function, and the island converter station also has a constant alternating voltage control function.
The auxiliary protection device is used for monitoring the ground fault of a metal return line layer of the flexible direct-current power grid, and sending a ground fault signal to the upper control device when the metal return line layer has the ground fault; the auxiliary protection device comprises an impedance monitoring device 41 of the ground resistance and a metal loop monitoring device 42.
The impedance monitoring device is used for dynamically monitoring the impedance of the grounding resistor, identifying the grounding fault of the grounding resistor, generating a grounding fault signal based on the grounding fault and sending the grounding fault signal to the upper control device.
The metal return line monitoring device is used for generating a ground fault signal based on the ground fault of the metal return line layer and sending the ground fault signal to the upper layer control device.
And the main protection device is used for calculating a differential current according to the current of the station and the current on the opposite side of the metal return wire layer, controlling a direct current change-over switch of the metal return wire layer according to the differential current to perform protection control so as to isolate the metal return wire layer with a fault, and sending a protection action signal to the upper control device.
It can be seen from the foregoing technical solutions that, this embodiment provides an earth fault protection system for a metal return line of a flexible dc power grid, including an upper control device, and a pole control device, a main protection device, and an auxiliary protection device, which are in signal connection with the upper control device. The auxiliary protection device is used for monitoring the ground fault of a metal return line layer of the flexible direct-current power grid, and sending a ground fault signal to the upper control device when the metal return line layer has the ground fault; the main protection device is used for calculating differential current according to the current of the station and the current on the opposite side of the metal return line layer, and controlling a direct current change-over switch of the metal return line layer to perform protection control according to the differential current. Therefore, the flexible direct-current power grid is protected, and the safe operation of the flexible direct-current power grid is guaranteed.
Example two
The present embodiment provides a protection control method, which is applied to the ground fault protection system for a metal return line of a flexible dc power grid provided in the previous embodiment. Specifically, the protection control method includes the following steps:
when the metal return line layer has a ground fault, the main protection device selects whether an outlet is tripped off the direct current change-over switch on the metal return line layer or not according to the protection criterion and a corresponding fixed value.
When the metal return line layer has a ground fault, the auxiliary protection device sends an alarm signal to the upper layer control device. And if the upper layer control device does not receive the action signal of the main protection device at the moment, sending control mode and control instruction information to each converter station to optimize and adjust the operation mode of each converter station of the flexible direct current power grid. The pole control device receives the signal and executes the following operations:
1) if the fault station (i.e. the converter station with the ground fault on the metal loop layer) is in a non-isolated island operation mode and the converter is in an active power control mode, sending the alarm information to the upper control device, so that the upper control device adjusts the fault converter station in the flexible direct current power grid into a bipolar unbalanced mode, further current on the metal loop is increased, and the main protection device judges whether a protection action fixed value is met or not and selects whether to switch off the direct current transfer switch.
2) If the fault station is in a non-island operation mode and the converter of the fault station is in a fixed direct-current voltage control mode, the alarm information is transmitted to the upper control device through the pole control device, other fixed active power converter stations in the flexible direct-current network are adjusted to be in a bipolar unbalanced operation mode through the upper control device, current on the metal loop is increased, and the main protection device judges whether the requirement for a protection action fixed value is met or not and selects whether an outlet is tripped out of the direct-current conversion switch or not.
3) And if the fault station is in an island operation mode, namely the converter is in an alternating current voltage control mode, transmitting the alarm information to an upper control device through a pole control device, and adjusting other certain active power converter stations in the power grid to be in a bipolar unbalanced operation mode through the upper control device. The system increases the current on the metal return wire by adjusting the operation mode to be a bipolar unbalanced operation mode, and the main protection device judges whether the fixed value of the protection action is met or not and selects whether the outlet is tripped off the direct current change-over switch or not.
If the power adjustment action is performed, the protection is still not actionable. At this time, the upper layer control device realizes grounding point transfer, namely, standby grounding points of other converter stations are closed, and the current grounding point is pulled. Through the transfer of the grounding point, the near-end grounding fault of the neutral line area can be converted into the far-end grounding fault, so that the current of the metal return line is further increased by increasing the shunting of the fault point, and the main protection device judges whether the requirement of a protection action fixed value is met or not and selects whether an outlet is tripped off the direct current conversion switch or not. .
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing terminal to cause a series of operational steps to be performed on the computer or other programmable terminal to produce a computer implemented process such that the instructions which execute on the computer or other programmable terminal provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.
The technical solutions provided by the present invention are described in detail above, and the principle and the implementation of the present invention are explained in this document by applying specific examples, and the descriptions of the above examples are only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (9)

1. The utility model provides a ground fault protection system of flexible direct current electric wire netting metallic return, its characterized in that, ground fault protection system includes upper control device, still include respectively with upper control device signal connection's utmost point controlling means, main protection device and auxiliary protection device, wherein:
the upper layer control device is used for receiving control instruction parameters of the pole control device, protection action signals of the main protection device and ground fault signals of the auxiliary device and sending operation control instructions to the pole control device;
the pole control device is arranged in a converter station of the flexible direct-current power grid and used for controlling a control mode, a line state and a converter valve state of the converter station based on the operation control instruction;
the auxiliary protection device is used for monitoring the ground fault of the metal return line layer of the flexible direct-current power grid, and sending a ground fault signal to the upper control device when the metal return line layer has the ground fault;
the main protection device is used for calculating a differential current according to the current of the station and the current on the opposite side of the metal return wire layer, controlling a direct current change-over switch of the metal return wire layer to perform protection control according to the differential current, and sending a protection action signal to the upper control device.
2. The ground fault protection system of claim 1, wherein the auxiliary protection device includes a ground resistance impedance monitoring device and a metallic return monitoring device.
3. The ground fault protection system of claim 2, wherein the ground resistance impedance monitoring device is configured to dynamically monitor the impedance of the ground resistance of the metal return line layer, to identify a ground fault of the ground resistance, to generate the ground fault signal based on the ground fault, and to send the ground fault signal to the upper control device.
4. The ground fault protection system of claim 2, wherein the metallic return monitoring device is configured to monitor the metallic return layer for a ground fault, generate the ground fault signal based on the ground fault, and send the ground fault signal to the upper control device.
5. The ground fault protection system of claim 1, wherein the flexible direct current power grid comprises a positive operating layer, a metal return line layer, and a negative operating layer, wherein:
the metal return wire layer is composed of a neutral bus and a metal return wire and is grounded through a grounding resistor.
6. The ground fault protection system of claim 7, wherein the metal return line layer is provided with the ground resistance ground point in at least two converter stations in a flexible direct current power grid.
7. A protection control method applied to the ground fault protection system of the metal return wire of the flexible direct current power grid according to any one of claims 1 to 6, characterized by comprising the following steps:
when the metal return line layer has a ground fault, the main protection device controls the direct current change-over switch to execute a protection action based on the differential current;
when the metal return layer has a ground fault, the auxiliary protection device sends an alarm message to the upper control device, and if the upper control device does not receive an action signal of the main protection device, the pole control device executes a preset power adjustment action and a ground station transfer action.
8. The protection control method of claim 7, wherein the preset power adjustment action comprises the steps of:
if the fault converter station with the ground fault is in a non-island operation mode and the converter of the fault converter station is in an active power control mode, sending the alarm information to the upper control device so that the upper control device can adjust the fault converter station in the flexible direct current power grid into a bipolar imbalance mode;
if the fault converter station is in a non-island operation mode and a converter of the fault converter station is in a fixed direct-current voltage control mode, sending the alarm information to the upper control device so that the upper control device can adjust other converter stations in the fixed active power mode in the flexible direct-current power grid to be in a bipolar unbalanced operation mode;
and if the fault converter station is in an island operation mode, namely a converter of the fault converter station is in an alternating current voltage control mode, transmitting the alarm information to the upper control device so that the upper control device adjusts other converter stations in the fixed active power mode in the flexible direct current network into a bipolar unbalanced operation mode.
9. The protection control method of claim 7, wherein the pre-set ground station transfer action comprises:
and the upper control device controls the converter station with the grounding point to carry out grounding point transfer, namely, standby grounding points of other converter stations are closed, and the current grounding point is pulled.
CN202111679371.3A 2021-12-31 2021-12-31 Ground fault protection system of flexible direct current power grid and protection control method thereof Pending CN114389234A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111679371.3A CN114389234A (en) 2021-12-31 2021-12-31 Ground fault protection system of flexible direct current power grid and protection control method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111679371.3A CN114389234A (en) 2021-12-31 2021-12-31 Ground fault protection system of flexible direct current power grid and protection control method thereof

Publications (1)

Publication Number Publication Date
CN114389234A true CN114389234A (en) 2022-04-22

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Application Number Title Priority Date Filing Date
CN202111679371.3A Pending CN114389234A (en) 2021-12-31 2021-12-31 Ground fault protection system of flexible direct current power grid and protection control method thereof

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