CN109962447B - Short-circuit current absorption branch exit control method and device based on overcurrent protection - Google Patents
Short-circuit current absorption branch exit control method and device based on overcurrent protection Download PDFInfo
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- CN109962447B CN109962447B CN201910106634.8A CN201910106634A CN109962447B CN 109962447 B CN109962447 B CN 109962447B CN 201910106634 A CN201910106634 A CN 201910106634A CN 109962447 B CN109962447 B CN 109962447B
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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
- H02H3/02—Details
- H02H3/025—Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection
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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
- H02H7/261—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 involving signal transmission between at least two stations
- H02H7/262—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 involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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- 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
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Abstract
The invention provides a method and a device for controlling exit of a short-circuit current absorption branch circuit based on overcurrent protection. The invention provides a short-circuit current absorption branch exit control method based on overcurrent protection, which comprises the following steps: generating a short-circuit current consumption branch exit instruction according to a first current in the short-circuit current consumption branch acquired at a first time and/or a second current in the short-circuit current consumption branch acquired at a second time; responding to the short-circuit current consumption branch exit instruction, and controlling the short-circuit current consumption branch to exit from the power grid; the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or switched out of the power grid. The method provided by the invention can timely withdraw the short-circuit current absorption branch circuit from the power system after the short-circuit fault in the power system is isolated, so that the system is recovered to a normal state as soon as possible.
Description
Technical Field
The invention belongs to the field of safety and stability control of an electric power system, and relates to a short-circuit current absorption branch exit control method and device based on overcurrent protection.
Background
With the continuous expansion of the scale of the power system, the implementation of networking planning and the gradual strengthening of the power grid, the short-circuit current level in the power system increases year by year. At present, the phenomenon that the short-circuit current level of the secondary voltage power grid exceeds the standard is common in China, and the phenomenon becomes an important problem for planning and operating the power grid. The problem of short-circuit current in local areas becomes a key factor for determining a power grid planning scheme and an operation mode.
At present, measures for limiting short-circuit current such as wire pulling, string discharging and string reactance adding are mainly adopted in the operation stage of a power grid, the quantity of local temporary measures is large, the range is wide, the structure and the reliability of the operation power grid are weakened, and the limitation on the trans-regional direct current transmission capacity is formed.
Disclosure of Invention
The invention provides a method and a device for controlling exit of a short-circuit current absorption branch circuit based on overcurrent protection, and aims to solve the problem that measures taken when the short-circuit current is too large cannot exit in time at present.
In a first aspect, the present invention provides a method for controlling exit of a short-circuit current absorption branch based on overcurrent protection, including:
generating a short-circuit current consumption branch exit instruction according to a first current in the short-circuit current consumption branch acquired at a first time and/or a second current in the short-circuit current consumption branch acquired at a second time;
wherein the first time is prior to the second time;
the first current is less than the second current;
responding to the short-circuit current consumption branch exit instruction, and controlling the short-circuit current consumption branch to exit from the power grid;
the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or switched out of the power grid.
In particular, the exit control method described herein,
and generating a short-circuit current consumption branch exit instruction when detecting that the first current in the short-circuit current consumption branch acquired at the first time is smaller than the preset working current and the second current in the short-circuit current consumption branch acquired at the second time is larger than the preset overcurrent current.
Specifically, the exit control method detects that the obtained second current in the short-circuit current absorption branch is greater than the preset overcurrent current in each of N consecutive detection periods, and generates a short-circuit current absorption branch exit instruction.
Specifically, the exit control method further includes:
and generating a short-circuit current absorption branch exit instruction when the on-off state of any fault protection switch in all the branches connected in parallel with the bus voltage acquired at the second time is off and when the second current in the short-circuit current absorption branch acquired at the second time is detected to be larger than the preset overcurrent current.
In particular, the exit control method described herein,
the short-circuit current absorption branch comprises a bidirectional thyristor which is controllably connected with or disconnected from the bus;
and the reactor is connected with the bidirectional thyristor in series and is grounded.
In a second aspect, the present invention provides a short-circuit current control device based on overcurrent protection, including:
the short-circuit current absorption branch current acquisition element is used for acquiring current information accessed by the short-circuit current absorption branch from the bus;
the control element is used for generating a short-circuit current consumption branch exit instruction according to the first current in the short-circuit current consumption branch acquired at the first time and/or the second current in the short-circuit current consumption branch acquired at the second time;
wherein the first time is prior to the second time;
the first current is less than the second current.
Specifically, the control device further includes:
the instruction driving element is used for receiving the short-circuit current absorption branch exit instruction and sending the short-circuit current absorption branch exit instruction to the short-circuit current absorption branch so that the short-circuit current absorption branch exits from the power grid in response to the short-circuit current absorption branch exit instruction;
the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or switched out of the power grid.
Specifically, the control device further includes:
the protection switch state acquisition element is used for receiving and processing the on-off signal of the protection switch;
the control element is further used for generating a short-circuit current absorbing branch exit instruction when the on-off state of any fault protection switch in all the branches connected in parallel with the bus voltage and acquired at the second time is off and when the second current in the short-circuit current absorbing branch acquired at the second time is detected to be larger than the preset overcurrent current.
Specifically, the control device further includes:
the short-circuit current absorption branch comprises a bidirectional thyristor which is controllably connected with or disconnected from the bus;
and the reactor is connected with the bidirectional thyristor in series and is grounded.
According to the short-circuit current absorption branch exit control method and device based on overcurrent protection, the short-circuit current absorption branch exit instruction is generated based on the current level accessed by the short-circuit current absorption branch, and the short-circuit current absorption branch can be timely exited from the power system after the short-circuit fault in the power system is isolated, so that the system can be restored to a normal state as soon as possible.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a schematic flow chart of a short-circuit current absorption branch exit control method based on overcurrent protection according to a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of the composition of a short-circuit current control device based on overcurrent protection in a preferred embodiment of the invention;
fig. 3 is a schematic flowchart of a short-circuit current absorption branch exit control method based on overcurrent protection according to another embodiment;
fig. 4 is a graph of current waveforms for thyristors before and after short circuit fault isolation in a preferred embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
At present, the phenomenon that the short-circuit current level of a secondary voltage power grid exceeds the standard is common. When any branch on an alternating current bus of a station such as a substation shown in fig. 2 has a short-circuit fault, a measure for limiting a short-circuit current needs to be taken in time to ensure that a fault protection switch is reliably disconnected and the fault is isolated in time. After fault isolation, the measures for limiting the short-circuit current need to be quitted in time, so that the system is restored to a normal state as soon as possible.
It should be understood that, in the event of a short-circuit fault in a branch, the fault protection switch K remains closed when a short-circuit current greater than the maximum short-circuit current that can be switched off flows, but continuously detects the short-circuit current in real time; the short-circuit protection switch is switched off until the flowing short-circuit current is reduced to be not more than the maximum short-circuit current which can be switched off; and after the fault is eliminated, the fault protection switch is closed and waits for the response to the next fault.
Specifically, the protection switch comprises a body and an operation element, wherein the operation element is used for controlling local switch opening or closing, generating an overcurrent state signal or an on-off state signal and providing the overcurrent state signal or the on-off state signal for other power system devices to perform state monitoring or logic judgment. As shown in fig. 2, the short-circuit current absorbing branch is installed on a bus of a station (e.g., a substation) to be detected. The short-circuit current accommodating branch comprises a power electronic switching device 10 which is controllably connected with or disconnected from the bus bar, and a reactor 20 connected with the power electronic switching device in series, wherein the reactor 20 is reliably grounded.
The short-circuit current absorption branch is equivalent to a parallel shunt branch which can be controllably connected to the bus when the short-circuit fault occurs in the power grid. Specifically, before the short-circuit fault occurs in the power grid, the short-circuit current absorbing branch is withdrawn from the power grid, or the current value obtained from the bus is approximately zero.
After the short-circuit fault occurs in the power grid, the short-circuit current absorption branch circuit is controlled to be put into the power grid, and a first larger current value is obtained from the bus before a protection switch of the short-circuit branch circuit is not switched off; and after the protection switch of the short-circuit branch is switched off, obtaining a larger second current value from the bus, wherein the second current value is larger than the first current value.
After the protective switch of the short-circuit branch is reliably opened, the short-circuit fault is isolated. In this case, the short-circuit current-absorbing branch needs to be controllably withdrawn from the grid, or the current value taken from the bus is approximately zero.
According to the short-circuit current absorption branch exit control method and the short-circuit current control device based on the overcurrent protection, the short-circuit current absorption branch exit instruction is generated based on the current level accessed by the short-circuit current absorption branch, so that the short-circuit current absorption branch can be timely exited from the power system after the short-circuit fault in the power system is isolated, and the system is ensured to be timely restored to the normal state.
Specifically, when the short-circuit current absorption branch is controlled to be disconnected with the bus, the probability of early disconnection needs to be minimized; and the probability of delayed disconnection is minimized.
As shown in fig. 1, the method for controlling exit of a short-circuit current absorption branch based on overcurrent protection in a preferred embodiment of the present invention includes:
step S100: generating a short-circuit current consumption branch exit instruction according to the first current in the short-circuit current consumption branch acquired at the first time and/or the second current in the short-circuit current consumption branch acquired at the second time;
wherein the first time is prior to the second time;
the first current is less than the second current;
step S200: responding to the short-circuit current consumption branch exit instruction, and controlling the short-circuit current consumption branch to exit from the power grid;
the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or out of the power grid.
It should be understood that the first time and the second time may be a single detection period or may refer to a plurality of consecutive detection periods. The detection period can be an update period of voltage quantity and current quantity updated by each measurement and control element in the intelligent substation, and can also be a sampling period of current signals acquired by a current detection device; and may also include time consuming transmissions over the communication link.
The first current or the second current refers to the amplitude of the current, which is connected from the bus by the short-circuit current absorption branch, and may be the absolute amplitude of the current or the relative amplitude.
The relative amplitude here can refer to the over-current signal state quantity, e.g., at over-current, the state quantity is 1; if not, the state quantity is 0; and the state quantity 1 is larger than the state quantity 0.
Specifically, the exit control method is provided,
and generating a short-circuit current consumption branch exit instruction when detecting that the first current in the short-circuit current consumption branch acquired at the first time is smaller than the preset working current and the second current in the short-circuit current consumption branch acquired at the second time is larger than the preset overcurrent current.
The method combines the historical information and the current information of the amplitude of the current accessed from the bus by the short-circuit current absorption branch, and when the rising and jumping trend of the current amplitude is detected, the short-circuit fault is considered to be isolated, the fault measures need to be quitted, and the system is ensured to be restored to the normal state in time.
The method has the advantages of more introduced information quantity and more comprehensive criteria, thus having good reliability and low false alarm rate.
Specifically, the exit control method detects that the obtained second current in the short-circuit current absorption branch is greater than the preset overcurrent current in each of N consecutive detection periods, and generates a short-circuit current absorption branch exit instruction.
In order to avoid misoperation caused by random peak values and other interference quantities in current amplitude measurement, when the obtained second current in the short-circuit current absorption branch is detected to be larger than the preset overcurrent current in the continuous N detection periods, the short-circuit fault is considered to be isolated, fault measures need to be withdrawn, and the system is ensured to be timely restored to a normal state.
The method has the advantages of more introduced information quantity and more comprehensive criteria, thus having good reliability and low false alarm rate.
Specifically, the exit control method further includes:
and generating a short-circuit current absorption branch exit instruction when the on-off state of any fault protection switch in all the branches connected in parallel with the bus voltage acquired at the second time is off and when the second current in the short-circuit current absorption branch acquired at the second time is detected to be larger than the preset overcurrent current.
In order to avoid early exit of exit measures caused by inaccurate current amplitude measurement, the method combines the open state of the protection starting end with the current rising criterion based on the fact that the switch on the branch circuit is necessarily in the open state after the short-circuit fault is isolated, ensures that the fault measures exit after the short-circuit fault is isolated, and ensures that the system is timely recovered to the normal state.
The method has the advantages of more introduced information quantity and more comprehensive criteria, thus having good reliability and low false alarm rate.
In particular, the exit control method described herein,
the short-circuit current absorption branch comprises a bidirectional thyristor which is controllably connected with or disconnected from the bus;
and the reactor is connected with the bidirectional thyristor in series and is grounded.
In a second aspect, the present invention provides a short-circuit current control device based on overcurrent protection, including:
the short-circuit current absorption branch circuit current acquisition element is used for acquiring current information accessed by the short-circuit current absorption branch circuit from a bus;
the control element is used for generating a short-circuit current consumption branch exit instruction according to the first current in the short-circuit current consumption branch acquired at the first time and/or the second current in the short-circuit current consumption branch acquired at the second time;
wherein the first time is prior to the second time;
the first current is less than the second current.
The short-circuit current absorption branch current acquisition element can acquire the absolute amplitude of the current and can also acquire the relative amplitude of the current.
Specifically, the control device further includes:
the instruction driving element is used for receiving the short-circuit current absorption branch exit instruction and sending the short-circuit current absorption branch exit instruction to the short-circuit current absorption branch so that the short-circuit current absorption branch exits from the power grid in response to the short-circuit current absorption branch exit instruction;
the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or switched out of the power grid.
Specifically, the control device further includes:
the protection switch state acquisition element is used for receiving and processing the on-off signal of the protection switch;
the control element is further used for generating a short-circuit current absorbing branch exit instruction when the on-off state of any fault protection switch in all the branches connected in parallel with the bus voltage and acquired at the second time is off and when the second current in the short-circuit current absorbing branch acquired at the second time is detected to be larger than the preset overcurrent current.
Specifically, the control device further includes:
the short-circuit current absorption branch comprises a bidirectional thyristor which is controllably connected with or disconnected from the bus;
and the reactor is connected with the bidirectional thyristor in series and is grounded.
The short-circuit current control device of the preferred embodiment of the invention controls the short-circuit current absorbing branch to be separated from the bus (including the situation that the current value obtained from the bus is approximate to zero), so that the short-circuit current absorbing branch can be withdrawn from the power system in time after the short-circuit fault in the power system is isolated, the measure amount during the short-circuit fault is reduced, and the safe and stable operation of the power grid is ensured.
It should be understood that the short-circuit current-absorbing branch shown in fig. 2 is equivalent to a reactor controllably connected to or disconnected from the bus bar. Various power electronic switching devices are used for controlling the reactor to be connected to or disconnected from the bus, and various electrical connection modes of the power electronic switching devices and the reactor are well known to those skilled in the art and are not described in detail here.
Usually, the short-circuit current absorbing branch and the corresponding short-circuit current control device are deployed with a single station as a minimum unit. In this case, the component properties and parameters of the short-circuit current absorption branch, the parameters of the short-circuit current control device and the control logic are adapted to the individual plant.
In particular, a current sensing device may be provided to obtain information quantitatively or qualitatively about the current drawn by the short-circuit current absorption branch from the bus bar.
Preferably, the power electronic switching device is a triac. As a power electronic device that can operate high power currents or voltages, a triac can also provide status signals in real time that indicate the level of access current and/or on-off status signals that indicate conduction (i.e., closed) or blocking (i.e., open). After parameter adaptation with a target loop or an electric power system, the bidirectional thyristor corresponds to a rated current I 1 And an overcurrent I 2 . After the bidirectional thyristor is closed, the working current is lower than the overcurrent current I 2 When the bidirectional thyristor is in the overcurrent state, the signal is 0 (indicating no overcurrent). After the bidirectional thyristor is closed, the working current is higher than the overcurrent current I 2 When the bidirectional thyristor is in the overcurrent state, the signal is 1 (indicating overcurrent).
As shown in fig. 2, the short-circuit current control device according to the preferred embodiment of the present invention can cover all the branches and their protection switches at the outlet of one station bus.
As shown in fig. 4, before and after a short-circuit fault occurs in any branch of the plant station and before and after fault isolation, in the first stage of the protection switch being closed and the triac being closed (at this time, the short-circuit current absorption branch is put into the power grid), the value of the working current accessed by the triac is lower than the rated current I 1 (ii) a In the second stage of the disconnection of the protective switch and the closing of the bidirectional thyristor (at this time, the short-circuit current absorption branch is put into the power grid), the working current connected into the bidirectional thyristor is higher than the overcurrent current I 2 (ii) a In the third phase of the disconnection of the protection switch and of the triac (in which case the short-circuit current absorption branch exits from the network), the value of the operating current switched in by the triac is much lower than the nominal current I 1 。
The following are the definitions of terms and symbols:
protection switch state signal:
boolean variable, 1 for closed, 0 for open
Overcurrent signals of the protection switch:
boolean variables, 1 for overcurrent and 0 for no overcurrent
Bidirectional thyristor overcurrent signal:
boolean variables, 1 for over-current and 0 for no-over-current
Bidirectional thyristor operating signal:
the boolean variable, 1 indicates closed and 0 indicates open.
As shown in fig. 3, the method for controlling exit of the short-circuit current absorption branch based on overcurrent protection includes the following steps:
a) the method comprises the following steps According to the protection switch on-off signal received from the protection switch state acquisition element 100
(indicating disconnection), the control element 200 judges whether a protection switch exists in the loop and is in a disconnected state, if so, the next step is carried out;
otherwise, the step is stopped, the control component 200 continues to receive and judge whether the protection switch on-off signal is satisfied or not
It should be understood here that the control element 200 logically and-processes the opening signals of the plurality of protection switches received from the protection switch state acquisition element 100; as long as there is a switching-off signal of the protection switch
(indicating a disconnection), it can be determined that the short circuit fault that occurred in the current bus has been reliably isolated.
b) The method comprises the following steps Based on the bidirectional received from thyristor state acquisition element 300Thyristor over-current signal
(indicating overcurrent), the control element 200 determines whether the triac is connected to excessive current from the bus; if so, generating a short-circuit current absorption branch exit instruction;
the instruction driving element 400 receives the short-circuit current absorbing branch exit instruction and sends the short-circuit current absorbing branch exit instruction to the triac 10 in the short-circuit current absorbing branch, and the triac 10 responds to the exit instruction to separate the short-circuit current absorbing branch from the ac bus, so that the short-circuit current absorbing branch exits from the power grid.
Preferably, since the short-circuit current control device is usually a real-time measurement and control system, the short-circuit current consumption branch exit instruction may be generated by combining the overcurrent signal of the triac in the current detection period and the overcurrent signal of the triac in other detection periods except the current detection period.
Specifically, for example, a queue of fixed length is maintained, and the overcurrent signal of the triac in M detection periods is stored in the queue according to the first-in first-out principle. When in the first M1 continuous detection periods, the overcurrent signal of the bidirectional thyristor is
(indicating no overcurrent); and in the last (M-M1) continuous detection periods, the overcurrent signal of the bidirectional thyristor is
(indicating overcurrent), the open circuit fault can be judged to be isolated, and the short-circuit current consumption branch where the bidirectional thyristor is located needs to be withdrawn from the power grid, so that a short-circuit current consumption branch withdrawal instruction is generated.
It should be noted that, according to the topological structure and the working principle of the short-circuit current absorption branch and the bus, in terms of time sequence, the reliable disconnection of the short-circuit protection switch occurs before, and the overcurrent signal generated by the bidirectional thyristor follows. The two have a causal relationship and a sequential relationship.
However, from the viewpoint of signal information acquisition and processing, the two signals need only satisfy a positive logical sum relationship, and are not necessarily limited to a sequential relationship.
In particular implementation, the thyristor state acquisition element 300 may not be provided as a separate device. When the electrical interface of the control element 200 can be matched with the electrical interface of the triac 10, the control element 200 can be directly connected with the triac 10 to directly obtain the triac overcurrent signal.
In particular implementations, command driver component 400 may not be provided separately as a discrete device. When the electrical interface of the control element 200 may be matched with the electrical interface of the triac 10, the control element 200 may be directly connected to the triac 10, and directly send a short-circuit current absorption branch exit instruction to the triac.
In specific implementation, the protection switch state obtaining element 100 may not be separately provided as a discrete device. The control element 200 may obtain the open-state signal or the overcurrent state signal of each protection switch from the intelligent substation.
The invention has been described above by reference to a few embodiments. However, other embodiments of the invention than the ones disclosed above are equally possible within the scope of these appended patent claims, as these are known to those skilled in the art.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
Claims (8)
1. A short-circuit current exit control method based on overcurrent protection is characterized by comprising the following steps:
generating a short-circuit current consumption branch exit instruction according to a first current in the short-circuit current consumption branch acquired at a first time and a second current in the short-circuit current consumption branch acquired at a second time, wherein the short-circuit current consumption branch exit instruction comprises the following steps: when detecting that a first current in the short-circuit current absorption branch acquired at a first time is smaller than a preset working current and a second current in the short-circuit current absorption branch acquired at a second time is larger than a preset overcurrent current, generating a short-circuit current absorption branch exit instruction;
wherein the first time is prior to the second time;
the first current is less than the second current;
responding to the short-circuit current consumption branch exit instruction, and controlling the short-circuit current consumption branch to exit from the power grid;
the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or switched out of the power grid.
2. The exit control method according to claim 1,
and detecting that the obtained second current in the short-circuit current absorption branch is greater than the preset overcurrent current in N continuous detection periods, and generating a short-circuit current absorption branch exit instruction.
3. The exit control method according to claim 1, characterized by further comprising:
and generating a short-circuit current absorption branch exit instruction when the on-off state of any fault protection switch in all the branches connected in parallel with the bus voltage acquired at the second time is off and when the second current in the short-circuit current absorption branch acquired at the second time is detected to be larger than the preset overcurrent current.
4. The exit control method according to claim 1,
the short-circuit current absorption branch comprises a bidirectional thyristor which is controllably connected with or disconnected from the bus;
and the reactor is connected with the bidirectional thyristor in series and is grounded.
5. A short-circuit current control device based on overcurrent protection is characterized by comprising:
the short-circuit current absorption branch circuit current acquisition element is used for acquiring current information accessed by the short-circuit current absorption branch circuit from a bus;
a control element for generating a short circuit current sinking branch exit command based on a first current in the short circuit current sinking branch taken at a first time and a second current in the short circuit current sinking branch taken at a second time, comprising: when detecting that a first current in the short-circuit current absorption branch acquired at a first time is smaller than a preset working current and a second current in the short-circuit current absorption branch acquired at a second time is larger than a preset overcurrent current, generating a short-circuit current absorption branch exit instruction;
wherein the first time is prior to the second time;
the first current is less than the second current.
6. The control device according to claim 5, characterized by further comprising:
the instruction driving element is used for receiving the short-circuit current absorption branch exit instruction and sending the short-circuit current absorption branch exit instruction to the short-circuit current absorption branch so that the short-circuit current absorption branch exits from the power grid in response to the short-circuit current absorption branch exit instruction;
the short-circuit current absorption branch circuit is a shunt branch circuit which is connected with the bus in parallel and can be controllably switched into or switched out of the power grid.
7. The control device according to claim 5, characterized by further comprising:
the protection switch state acquisition element is used for receiving and processing the on-off signal of the protection switch;
the control element is further used for generating a short-circuit current absorbing branch exit instruction when the on-off state of any fault protection switch in all the branches connected in parallel with the bus voltage and acquired at the second time is off and when the second current in the short-circuit current absorbing branch acquired at the second time is detected to be larger than the preset overcurrent current.
8. The control device according to claim 5, characterized by further comprising:
the short-circuit current absorption branch comprises a bidirectional thyristor which is controllably connected with or disconnected from the bus;
and the reactor is connected with the bidirectional thyristor in series and is grounded.
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Citations (7)
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| CN109962447A (en) | 2019-07-02 |
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