CN109256861B - Substation area failure protection system and method for rapidly isolating faults of multiple direct-current power grids - Google Patents
Substation area failure protection system and method for rapidly isolating faults of multiple direct-current power grids Download PDFInfo
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- H02J13/0003—
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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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- 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
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- 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
- Y04S10/16—Electric power substations
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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
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- 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
Abstract
The invention discloses a station domain failure protection system and a method for rapidly isolating faults of a multi-direct-current power grid, which can shorten the fault isolation time from the traditional 400ms to 200ms, reduce transient energy impact during the fault period of the power grid, reduce the direct-current commutation failure risk caused by alternating-current fault disturbance, and greatly improve the safe and stable operation level of the power grid. The provided station domain failure protection system can achieve the acquisition of voltage, current and breaker position data of the whole station through a layered configuration scheme of the main station and the substation. Information interaction can be carried out among different main stations, information interaction such as the position of a breaker of a related transformer substation, current data and line protection actions is achieved, and the sensing range of the station domain failure protection system is expanded. By means of the differential ring design scheme of the station domain failure protection, the traditional failure protection criterion is replaced, and rapid identification and isolation of failure faults and dead zone faults are achieved.
Description
Technical Field
The invention relates to a station domain failure protection system and a scheme for rapidly isolating faults of multiple direct-current power grids, and belongs to the field of relay protection of power systems.
Background
In the construction transition period of the extra-high voltage power grid, the characteristic of strong direct current and weak alternating current of the power grid is prominent, the grid-connected capacity of new energy equipment such as wind power and photovoltaic equipment is continuously increased, the grid pattern and the power structure are greatly changed, and the recognition method, defense concept and control technology formed based on the traditional alternating current system are lagged behind the operation practice of the extra-high voltage alternating current and direct current power grid. In recent years, events of failure of commutation of a direct current system caused by faults of the alternating current system occur successively in China. The voltage drop and distortion of a current conversion bus are caused by the drop of the amplitude of alternating voltage and the distortion of the waveform caused by the fault of an alternating current power grid, and a direct current system can amplify the power of small disturbance and conduct the disturbance between a transmitting end and a receiving end.
After the alternating current system has a short-circuit fault, the fault can not be quickly removed due to the failure of a breaker of the breaker, the fault duration is prolonged, the direct current continuous commutation failure or direct current blocking risk is increased, large-scale power oscillation is easily caused, the tidal current is transferred in a large range, other cascading faults can be caused, and the consequences are very serious. When the direct current commutation failure occurs in the extra-high voltage alternating current and direct current hybrid power grid, the power fluctuation of the power grid is caused to be about 200ms, and the large-scale power flow transfer of the power grid is caused. The action time of the traditional failure protection is about 400ms, the research about the failure protection is limited to the optimization by utilizing the criteria of an alternating current system, certain limitations exist, the influence of CT tailing cannot be thoroughly solved, the failure protection fault removal time is difficult to be greatly shortened, the direct current continuous commutation failure during the fault cannot be solved, and the requirement of stable operation of an extra-high voltage alternating current and direct current power grid cannot be completely met.
Disclosure of Invention
In order to solve the technical problems, the invention provides a station domain failure protection system and a method for realizing rapid isolation of multiple direct current power grid faults, which effectively shorten the time for removing failure faults and dead zone faults, reduce the risks of direct current commutation failure and locking caused by alternating current system faults, ensure the operation safety of a large power grid,
in order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a multi-direct-current power grid fault rapid isolation substation area failure protection system comprises a substation control layer, a spacer layer and a process layer, wherein the substation control layer, the spacer layer and the process layer are arranged in a layered mode from top to bottom, a main station and a sub station are arranged on the spacer layer, operation data acquisition of a transformer substation is achieved, the main station is arranged on the substation control layer, and total station information and a substation area failure protection action outlet are obtained through the sub station.
The master station is configured based on the transformer substation, and the substation is configured based on the string;
each transformer substation is provided with a master station, and the master station acquires voltage information, current information, breaker state information and relay protection action information of the whole transformer substation through the slave station; the method comprises the following steps that communication connection is carried out between adjacent substation main stations, and the main stations obtain information of adjacent substations; the master station accesses a time synchronization device signal;
the substation comprises a string substation and a transformer substation, wherein the string substation is configured based on a transformer substation string, and each transformer substation string is configured with one string substation; the transformer substations are configured on the basis of transformers, and each transformer is independently configured with one transformer substation; the substation accesses a time synchronization device signal;
the substation acquires operation information in the substation string, wherein the operation information in the substation string comprises: real-time current information, voltage information, circuit breaker position information and line protection information in the transformer substation string; the transformer substation acquires three-side information (three high, medium and low sides of three coils of transformers) of the transformer, wherein the three-side information of the transformer comprises current information, voltage information, circuit breaker position information and main transformer protection action information of three sides of the real-time transformer; the substation acquires running information in the string or information on three sides of the transformer and then sends the running information or the information to the main station;
the main station acquires information sent by each string of substations and information of the transformer substations, receives bus protection action information, and acquires opposite-side information and opposite-side line protection action information of a line connected with the transformer substation through adjacent main stations.
A station domain failure protection method for rapidly isolating faults of a multi-direct-current power grid comprises the following steps:
step 1: the control substation transmits running information in the transformer substation string and three-side information of the transformer to the master station, and the master station acquires the information of the whole substation;
step 2: adjacent master stations exchange associated line information, and the master stations acquire universe information;
and step 3: according to the fault of the power grid, the main station constructs a differential ring according to relay protection action information and switch position information, differential ring configuration is carried out, and relay protection sends out action information;
and 4, step 4: starting a station domain failure protection logic, and controlling the sub-station to block a current transformer of a corresponding circuit breaker according to action information sent by relay protection;
and 5: according to the information of blocking the current transformer, the main station starts a differential ring protection criterion; the differential ring protection criterion replaces the traditional failure protection criterion;
step 6: and a station domain failure protection action outlet, a breaker is tripped, and differential ring differential current returns.
The step 1 specifically comprises the following steps:
(101) the substation acquires running information in the substation string, and after acquiring real-time information in the substation string, the substation performs synchronous processing according to data time scales;
(102) the transformer substation is connected with three sides of the transformer substation, and after the transformer substation acquires the real-time information of the transformer substation, synchronous processing is carried out according to data time scales;
(103) the serial substation and the transformer substation upload acquired real-time information to the master station, the bus differential ring protection uploads action information to the master station in real time, and the master station acquires information of the total station;
(104) and the master station synchronously processes the total station information according to the time mark data in the total station information, and acquires the total station information of the total station unified time mark.
The step 2 specifically comprises the following steps:
(201) the method comprises the following steps that real-time information of associated lines is exchanged between adjacent master stations, and the master stations acquire the real-time information of all circuit breakers in the transformer substation;
(202) and carrying out synchronous processing according to the time mark data in the real-time information exchanged by the adjacent master stations, wherein the master stations acquire the global information with unified time marks.
The differential ring comprises a line differential ring and a bus differential ring; the line differential ring is a minimum differential area surrounded by a Current Transformer (CT) of a circuit breaker surrounding the line; the bus differential ring is a minimum differential area surrounded by a current transformer of a circuit breaker surrounding the bus; the line differential ring comprises a first line differential ring and a second line differential ring; the first line differential ring is a minimum differential area surrounded by a current transformer of the side switch circuit breaker; the second line differential ring is the smallest differential area surrounded by the current transformers of the open-close circuit breaker.
The step 3 specifically comprises the following steps:
(301) the differential ring configuration is configured according to a bus differential ring and a line differential ring;
the bus differential ring is configured according to buses, and one bus is configured with one bus differential ring; under the condition of no fault, the vector current flowing into the bus differential ring is zero, and after the bus differential ring is used for line protection action, the side switch fails and refuses to act;
the line differential ring is configured according to lines, and one line is configured with one line differential ring; the line differential ring comprises an open circuit breaker and a side switch circuit breaker of substations on two sides of a connecting line, and the vector current flowing into the line differential ring is zero under the condition of no fault;
(302) if the line is in fault, the line is protected, and after the string substation receives the line protection action information, the line protection action information is uploaded to the master station;
(303) and if the bus fails, the bus differential ring protection acts, and the bus differential ring protection action information is sent to the main station.
The step 4 specifically comprises the following steps:
(401) if the bus differential ring protection action occurs, the side switch dead zone fault occurs, the substation receives the side switch breaker jump position, and the main station monitors the side switch breaker to change the on position into the jump position through the substation; after a substation in a string where the side switch circuit breaker is located receives the jumping position of the side switch circuit breaker, the side switch locks a current sensor on the side of the circuit breaker, and the current of the current sensor on the side of the side switch circuit breaker is zero on the substation;
(402) if the bus differential ring protection action occurs, the side switch breaker fails to reject tripping, the string substation where the side switch breaker is located does not receive the tripping position of the breaker, and the main station does not receive the tripping position of the side switch breaker sent by the substation;
judging that the switch breaker fails while switching the breaker at the substation where the switch breaker is located, and rejecting tripping of the switch breaker while switching the breaker; the substation sends the tripping-resistant result of the side switch breaker to the main station;
the master station receives a side switch breaker protection action signal of bus differential protection and receives a side switch breaker bounce rejection signal sent by the substation;
the current transformer corresponding to the side switch breaker is blocked by the substation, the current sent to the side switch breaker of the main station is zero,
the main station of the station domain failure protection constructs differential current of a first line differential ring, and the differential current is out of limit;
(403) if the circuit protection action occurs, the side switch breaker fails and refuses to act; the main station receives a tripping command of the side switch breaker;
the sub-station locks the current sensor corresponding to the breaker, the current of the breaker sent to the main station is zero,
the main station of the station domain failure protection constructs differential current of a bus differential ring, and the differential current is out of limit;
(404) if the circuit protection action occurs, the open-close circuit breaker fails and refuses to act; the master station receives a command of tripping the open/close circuit breaker;
the current transformer corresponding to the open-close circuit breaker is blocked by the substation, the current of the open-close circuit breaker which is sent to the main station is zero,
and the main station for the station domain failure protection establishes the differential current of the differential ring of the second line, and the differential current is out of limit.
The differential ring protection criterion specifically comprises the following steps:
the main station of the station domain failure protection constructs differential current of a differential ring, the differential current is out of limit, and failure protection of a dynamic ring is started; the differential ring has y branches, each branch having a current of IΦx(x ═ 1,2.. y), the differential current of the failure protection conventional proportional differential startup element of the differential loop is:
where Φ represents a three-phase current A, BAny one of phases C, IdΦIn order to be a differential current flow,
a differential start threshold value;
the sudden change differential current of the failure protection sudden change proportional differential starting element of the differential ring is as follows:
wherein, Delta IdΦIn order to make the differential current of the amount of the mutation,
for differential start of threshold, Δ I, for sudden changesΦxIs the sudden change of branch current;
the relation of logic OR is between the failure protection conventional proportional differential starting element and the failure protection sudden change proportional differential starting element;
the differential current, brake current and sudden change differential start thresholds of the differential loop fail-safe proportional differential element are:
wherein, IrΦFor braking current, IsetIs the threshold value of the differential current, and,
is a differential current action value, KrIs a conventional rate braking coefficient;
the differential current and the abrupt change differential current of the failure protection abrupt change proportional differential element of the differential ring are as follows:
wherein, Kr' is the amount of mutationA proportional braking coefficient; delta IrΦIs an abrupt change in differential current;
the failure protection proportional differential element and the failure protection abrupt variable proportional differential element are in an OR relationship.
The beneficial effects of the invention include: the invention discloses a substation area failure protection system for rapidly isolating faults of a multi-direct-current power grid. Information interaction can be carried out among different main stations, information interaction such as the position of a breaker of a related transformer substation, current data and line protection actions is achieved, and the sensing range of the station domain failure protection system is expanded. By means of the differential ring design scheme of the station domain failure protection, the traditional failure protection criterion is replaced, and rapid identification and isolation of failure faults and dead zone faults are achieved.
The invention provides a station domain failure protection method for realizing rapid isolation of multiple direct current power grid faults, which can ensure that the fault clearing time can be shortened from 400ms to about 200ms after the power grid has dead zone faults or when a breaker fails and fails. Due to the adoption of the station domain failure protection system method, when dead zone faults or circuit breaker failure faults occur in the direct current drop point near region, the fault removal speed is greatly increased. The low voltage duration is shortened during the fault period of the power grid, the probability of multiple continuous commutation failures of direct current is reduced, the transient energy impact of the power grid caused by the direct current is greatly reduced, the instability risk of the power grid caused by the transient energy impact is reduced, and the safe and stable operation level of the extra-high voltage alternating current and direct current hybrid power grid is improved. Taking the simulation analysis result of the Jiangsu power grid as an example, after the failure protection action of part of circuit breakers after the failure action, after the fault clearing time is shortened, direct current of 3 continuous commutation failures occurs, and only 2 continuous commutation failures may occur, so that the system stability is greatly improved. The method and the device realize rapid identification of the dead zone fault and the fault of failure and refusal of the breaker, improve the failure protection and the fault removal speed of the dead zone fault, and improve the safe operation level of the power grid.
Drawings
The invention is further explained below with reference to the figures and examples;
fig. 1 is a schematic structural diagram of a station domain fault protection system for realizing rapid fault isolation of multiple direct-current power grids according to the present invention;
FIG. 2 is a method of configuring master stations and substations of the present invention;
FIG. 3 is a flow chart of a station domain failure protection method for achieving rapid fault isolation of multiple direct current power grids according to the invention;
FIG. 4 is a flow chart of differential ring protection criteria according to the present invention;
FIG. 5 is a logic flow diagram of the station domain failover protection of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments, which are illustrative only and not limiting, and the scope of the present invention is not limited thereby.
In order to achieve the objectives and effects of the technical means, creation features, working procedures and using methods of the present invention, and to make the evaluation methods easy to understand, the present invention will be further described with reference to the following embodiments.
The invention will now be further described, by way of example, with reference to the accompanying drawings.
As shown in fig. 1, a multi-dc power grid fault fast-isolation station-domain failure protection system includes a station control layer, a spacer layer and a process layer, wherein the substation and the master station are configured in a layered manner from top to bottom, the slave station is configured at the spacer layer to realize the collection of the operation data of a transformer substation, the master station is configured at the station control layer, and the master station acquires the information of the whole station and a station-domain failure protection action exit through the slave station.
The station domain failure protection master station sends the station domain failure protection action information to an SCADA (Supervisory Control And Data Acquisition) system (Data Acquisition And monitoring Control system) through MMS (IEC-61850 message specification).
As shown in fig. 2, the master station is configured based on a substation, and the substations are configured based on strings;
each transformer substation is provided with a master station, and the master station acquires voltage information, current information, breaker state information and relay protection action information of the whole transformer substation through the slave station; the method comprises the following steps that communication connection is carried out between adjacent substation main stations, and the main stations obtain information of adjacent substations; the master station is accessed to a time synchronizer signal and has data synchronization capacity.
The substation comprises a string substation and a transformer substation, wherein the string substation is configured based on a transformer substation string, and each transformer substation string is configured with one string substation; the transformer substations are configured on the basis of transformers, and each transformer is independently configured with one transformer substation; the sub-station is accessed to the time synchronizer signal and has the data synchronization capability.
The string substation acquires operation information in a transformer substation string, and the method comprises the following steps: real-time current information, voltage information, circuit breaker position information and line protection information in the transformer substation string; the transformer substation acquires three-side information (three high, medium and low sides of three coils of transformers) of the transformer, wherein the three-side information of the transformer comprises current information, voltage information, circuit breaker position information and main transformer protection action information of three sides of the real-time transformer; and the substation acquires the running information in the string or the information on three sides of the transformer and then sends the running information or the information on three sides of the transformer to the main station.
The main station acquires information sent by each string of substations and information of the transformer substations, receives bus protection action information, and acquires opposite-side information and opposite-side line protection action information of a line connected with the transformer substation through adjacent main stations.
As shown in fig. 3, a station domain failure protection method for fast isolating multiple direct current grid faults includes the following steps:
step 1: the control substation transmits running information in the transformer substation string and three-side information of the transformer to the master station, and the master station acquires the information of the whole substation;
step 2: adjacent master stations exchange associated line information, and the master stations acquire universe information;
and step 3: according to the fault of the power grid, the main station constructs a differential ring according to relay protection action information and switch position information, differential ring configuration is carried out, and relay protection sends out action information;
and 4, step 4: starting a station domain failure protection logic, and controlling the sub-station to block a current transformer of a corresponding circuit breaker according to action information sent by relay protection;
and 5: according to the information of blocking the current transformer, the main station starts a differential ring protection criterion; the differential ring protection criterion replaces the traditional failure protection criterion;
step 6: and a station domain failure protection action outlet, a breaker is tripped, and differential ring differential current returns.
The step 1 specifically comprises the following steps:
(101) the substation obtains operation information A in the substation string, wherein the operation information A in the substation string comprises real-time current information, voltage information, breaker position information and line protection information in the substation string of the substation string; the method comprises the steps that after real-time information of different intervals and equipment in a substation string is obtained, synchronous processing is carried out according to data time scales by a string substation;
(102) the transformer substation is accessed with three-side information of a transformer substation, the three-side information of the transformer comprises current information, voltage information, position information of a circuit breaker and main transformer protection action information on three sides of the transformer, and after the transformer substation acquires real-time information of different intervals and equipment of the transformer substation, the transformer substation carries out synchronous processing according to data time scales;
(103) the serial substation and the transformer substation upload acquired real-time information to the master station, the bus differential ring protection uploads action information to the master station in real time, and the master station acquires information of the total station;
(104) and the master station synchronously processes the total station information according to the time mark data in the total station information, and acquires the total station information of the total station unified time mark.
The step 2 specifically comprises the following steps:
(201) the method comprises the steps that real-time information of associated lines is exchanged by adjacent master stations, wherein the real-time information comprises line voltage and current data, line protection action information and line breaker position information of the associated lines, and the master stations acquire the real-time information of all circuit breakers in the transformer substation;
(202) and carrying out synchronous processing according to the time mark data in the real-time information exchanged by the adjacent master stations, wherein the master stations acquire the global information with unified time marks.
As shown in fig. 4, the differential ring includes a line differential ring and a bus differential ring; the line differential ring is a minimum differential area surrounded by a Current Transformer (CT) of a circuit breaker surrounding the line; the bus differential ring is a minimum differential area surrounded by a current transformer of a circuit breaker surrounding the bus; the line differential ring comprises a first line differential ring and a second line differential ring; the first line differential ring is a minimum differential area surrounded by a current transformer of the side switch circuit breaker; the second line differential ring is the smallest differential area surrounded by the current transformers of the open-close circuit breaker.
The step 3 specifically comprises the following steps:
(301) the differential ring configuration is configured according to a bus differential ring and a line differential ring, after relay protection action occurs, the master station starts differential ring action logic, calculates fault positions and failure protection action ranges, and executes station domain failure protection action logic through the substation to disconnect corresponding circuit breakers and remove faults.
The bus differential ring is configured according to buses, and one bus is configured with one bus differential ring; the bus differential ring comprises the current bus and all branches thereof, the vector current flowing into the bus differential ring is zero under the condition of no fault, and the side switch fails and refuses to operate after the bus differential ring is used for line protection.
The line differential ring is configured according to lines, and one line is configured with one line differential ring; the line differential ring comprises a middle switch and a side switch of substations on two sides of a connecting line, and the vector current flowing into the line differential ring is zero under the condition of no fault. The line differential ring is used for switch failure and jump rejection after bus protection action, side switch dead zone fault, or switch failure and jump rejection after the protection action of another line in the same series.
(302) If the line is in fault, the line is protected, and after the string substation receives the line protection action information, the line protection action information is uploaded to the master station;
(303) and if the bus fails, the bus differential ring protection acts, and the bus differential ring protection action information is sent to the main station.
As shown in fig. 5, step 4 specifically includes the following steps:
(401) if the bus differential ring protection action occurs, a side switch dead zone fault occurs, if a fault occurs at the point F2, the substation receives the side switch breaker DL21 jump position, and the master station monitors the side switch breaker DL21 through the substation to change the closing position into the jump position; after the substation of the string where the side switch breaker DL21 is located receives the jump position of the side switch breaker DL21, the side switch blocks the CT at the side of the breaker DL21, and the CT current at the side of the side switch breaker DL21 uploaded by the substation is zero;
the failure protection of the first line differential ring is subjected to anti-shake processing and time delay, and the action outlet performs failure protection action through the substation to protect the circuit breaker of the jump differential ring 2.
(402) If the bus differential ring protection action occurs, the side switch breaker DL21 fails to reject the tripping, the string substation where the side switch breaker DL21 is located does not receive the tripping bit of the breaker DL21, and the main station does not receive the tripping bit of the side switch breaker DL21 sent by the substation;
the substation where the side switch breaker DL21 is located judges that the side switch breaker DL21 is out of order and the breaker rejects tripping; the sub station sends the result of the side switch breaker DL21 refusing to the main station.
The master station receives a bus differential protection side switch breaker DL21 protection action signal and receives a side switch breaker DL21 bounce rejection signal sent by the substation;
the current sent to the side switch breaker DL21 of the master station is zero by the CT corresponding to the side switch breaker DL21 sealed and locked by the substation,
the main station of the station domain failure protection constructs differential current of a first line differential ring, and the differential current is out of limit;
the failure protection of the first line differential ring is performed by the anti-shake processing and time delay, and the action exit is used for executing failure protection action through the sub-station to protect the circuit breaker of the first differential ring (differential ring 2 in figure 4) of the jump line.
(403) If the line protection action occurs, the side switch breaker DL21 fails and refuses to act. The master station receives a tripping command of the side switch breaker DL 21;
the CT corresponding to the secondary station blocking breaker DL21, the current of the breaker DL21 which is sent to the main station is zero,
the main station for the station domain failure protection constructs the differential current of a bus differential ring (figure 4 differential ring 1), and the differential current exceeds the limit to start the station domain failure protection logic of the bus differential ring.
The failure protection of the bus differential ring is subjected to anti-shake processing and time delay, and an action outlet performs failure protection actions through a substation to protect a jump bus differential ring breaker.
(404) If the circuit protection action occurs, the open/close circuit breaker DL22 fails and refuses to act; the master station receives the open shunt DL22 hopped command.
The CT corresponding to the switch-off circuit breaker DL22 is blocked by the substation, the current sent to the switch-off circuit breaker DL22 of the main station is zero,
the main station of the station domain failure protection constructs the differential current of a second line differential ring (figure 4 differential ring 3), and the differential current is out of limit;
and the failure protection of the second line differential ring is subjected to anti-shake processing and time delay, and the action outlet performs failure protection action through the substation to protect the circuit breaker jumping the second line differential ring.
The differential ring protection criterion specifically comprises the following steps: :
the main station of the station domain failure protection constructs differential current of a differential ring, the differential current is out of limit, and failure protection of a dynamic ring is started; the differential ring has y branches, each branch having a current of IΦx(x ═ 1,2.. y), the differential current of the failure protection conventional proportional differential startup element of the differential loop is:
where Φ represents any one phase of three-phase current A, B, C, IdΦIn order to be a differential current flow,
a differential start threshold value;
the sudden change differential current of the failure protection sudden change proportional differential starting element of the differential ring is as follows:
wherein, Delta IdΦIn order to make the differential current of the amount of the mutation,
for differential start of threshold, Δ I, for sudden changesΦxIs the branch current break variable.
The relation between the normal proportion differential starting element of the failure protection and the sudden change proportion differential starting element of the failure protection is logical OR, and the starting element is automatically widened for 500ms as long as any starting element is started.
The differential current, brake current and sudden change differential start thresholds of the differential loop fail-safe proportional differential element are:
wherein, IrΦFor braking current, IsetIs the threshold value of the differential current, and,
for the differential current action value, this embodiment is equal to the differential current threshold value, KrIs a conventional rate braking coefficient; example KrThe value of 0.4, the small differential proportional braking coefficient K of the double bus, the double bus double segmentation and the double bus single segmentationrValue of 0.5, large differential proportional braking coefficient KrThe value is 0.3.
The differential current and the abrupt change differential current of the failure protection abrupt change proportional differential element of the differential ring are as follows:
wherein, Kr' is the brake coefficient of the mutation quantity proportion, and a fixed value is 0.65; delta IrΦIs an abrupt magnitude differential current.
The failure protection proportional differential element and the failure protection abrupt variable proportional differential element are in an OR relationship.
Those skilled in the art can design the invention to be modified or varied without departing from the spirit and scope of the invention. Therefore, if such modifications and variations of the present invention fall within the technical scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (8)
1. A multi-direct-current power grid fault rapid isolation substation area failure protection system is characterized by comprising a substation control layer, a spacer layer and a process layer, wherein the substation control layer, the spacer layer and the process layer are configured in a layered mode from top to bottom by adopting a main station and a substation, the substation is configured at the spacer layer to realize operation data acquisition of a transformer substation, the main station is configured at the substation control layer, and the main station acquires total station information and a substation area failure protection action outlet through the substation;
the station domain failure protection method of the system comprises the following steps:
step 1: the control substation transmits running information in the transformer substation string and three-side information of the transformer to the master station, and the master station acquires the information of the whole substation;
step 2: adjacent master stations exchange associated line information, and the master stations acquire universe information;
and step 3: according to the fault of the power grid, the main station constructs a differential ring according to relay protection action information and switch position information, differential ring configuration is carried out, and relay protection sends out action information;
and 4, step 4: starting a station domain failure protection logic, and controlling the sub-station to block a current transformer of a corresponding circuit breaker according to action information sent by relay protection;
and 5: according to the information of blocking the current transformer, the main station starts a differential ring protection criterion;
step 6: the station domain failure protection action outlet, the breaker tripping and the differential ring differential current return;
the step 3 specifically comprises the following steps:
(301) the differential ring configuration is configured according to a bus differential ring and a line differential ring;
the bus differential ring is configured according to buses, and one bus is configured with one bus differential ring; under the condition of no fault, the vector current flowing into the bus differential ring is zero, and after the bus differential ring is used for line protection action, the side switch fails and refuses to act;
the line differential ring is configured according to lines, and one line is configured with one line differential ring; the line differential ring comprises an open circuit breaker and a side switch circuit breaker of substations on two sides of a connecting line, and the vector current flowing into the line differential ring is zero under the fault-free condition;
(302) if the line is in fault, the line is protected, and after the string substation receives the line protection action information, the line protection action information is uploaded to the master station;
(303) and if the bus fails, the bus differential ring protection acts, and the bus differential ring protection action information is sent to the main station.
2. The multiple direct current grid fault rapid isolation station domain fault protection system of claim 1,
the master station is configured based on the transformer substation, and the substation is configured based on the string;
each transformer substation is provided with a master station, and the master station acquires voltage information, current information, breaker state information and relay protection action information of the whole transformer substation through the slave station; the method comprises the following steps that communication connection is carried out between adjacent substation main stations, and the main stations obtain information of adjacent substations; the master station accesses a time synchronization device signal;
the substation comprises a string substation and a transformer substation, wherein the string substation is configured based on a transformer substation string, and each transformer substation string is configured with one string substation; the transformer substations are configured on the basis of transformers, and each transformer is configured with one transformer substation; the substation accesses a time synchronization device signal;
the substation acquires operation information in the substation string, wherein the operation information in the substation string comprises: real-time current information, voltage information, circuit breaker position information and line protection information in the transformer substation string; the transformer substation acquires three-side information of a transformer, wherein the three-side information of the transformer comprises current information, voltage information, circuit breaker position information and main transformer protection action information of three sides of the real-time transformer; the substation acquires running information in the string or information on three sides of the transformer and then sends the running information or the information to the main station;
the main station acquires information sent by each string of substations and information of the transformer substations, receives bus protection action information, and acquires opposite-side information and opposite-side line protection action information of a line connected with the transformer substation through adjacent main stations.
3. A station domain failure protection method for rapidly isolating faults of a multi-direct-current power grid is characterized by comprising the following steps:
step 1: the control substation transmits running information in the transformer substation string and three-side information of the transformer to the master station, and the master station acquires the information of the whole substation;
step 2: adjacent master stations exchange associated line information, and the master stations acquire universe information;
and step 3: according to the fault of the power grid, the main station constructs a differential ring according to relay protection action information and switch position information, differential ring configuration is carried out, and relay protection sends out action information;
and 4, step 4: starting a station domain failure protection logic, and controlling the sub-station to block a current transformer of a corresponding circuit breaker according to action information sent by relay protection;
and 5: according to the information of blocking the current transformer, the main station starts a differential ring protection criterion;
step 6: the station domain failure protection action outlet, the breaker tripping and the differential ring differential current return;
the step 3 specifically comprises the following steps:
(301) the differential ring configuration is configured according to a bus differential ring and a line differential ring;
the bus differential ring is configured according to buses, and one bus is configured with one bus differential ring; under the condition of no fault, the vector current flowing into the bus differential ring is zero, and after the bus differential ring is used for line protection action, the side switch fails and refuses to act;
the line differential ring is configured according to lines, and one line is configured with one line differential ring; the line differential ring comprises an open circuit breaker and a side switch circuit breaker of substations on two sides of a connecting line, and the vector current flowing into the line differential ring is zero under the fault-free condition;
(302) if the line is in fault, the line is protected, and after the string substation receives the line protection action information, the line protection action information is uploaded to the master station;
(303) and if the bus fails, the bus differential ring protection acts, and the bus differential ring protection action information is sent to the main station.
4. The method for fast isolating station domain failure protection of multiple direct current grid faults according to claim 3,
the step 1 specifically comprises the following steps:
(101) the substation acquires running information in the substation string, and after acquiring real-time information in the substation string, the substation performs synchronous processing according to data time scales;
(102) the transformer substation is connected with three sides of the transformer substation, and after the transformer substation acquires the real-time information of the transformer substation, synchronous processing is carried out according to data time scales;
(103) the serial substation and the transformer substation upload acquired real-time information to the master station, the bus differential ring protection uploads action information to the master station in real time, and the master station acquires information of the total station;
(104) and the master station synchronously processes the total station information according to the time mark data in the total station information, and acquires the total station information of the total station unified time mark.
5. The method for fast isolating station domain failure protection of multiple direct current grid faults according to claim 3,
the step 2 specifically comprises the following steps:
(201) the method comprises the following steps that real-time information of associated lines is exchanged between adjacent master stations, and the master stations acquire the real-time information of all circuit breakers in the transformer substation;
(202) and carrying out synchronous processing according to the time mark data in the real-time information exchanged by the adjacent master stations, wherein the master stations acquire the global information with unified time marks.
6. A method for fast isolating station domain fault protection of multiple direct current grid faults according to claim 3,
the differential ring comprises a line differential ring and a bus differential ring; the line differential ring is a minimum differential area surrounded by a current transformer of a circuit breaker surrounding the line; the bus differential ring is a minimum differential area surrounded by a current transformer of a circuit breaker surrounding the bus; the line differential ring comprises a first line differential ring and a second line differential ring; the first line differential ring is a minimum differential area surrounded by a current transformer of the side switch circuit breaker; the second line differential ring is the smallest differential area surrounded by the current transformers of the open-close circuit breaker.
7. The method for fast isolating station domain failure protection of multiple direct current grid faults according to claim 3,
the step 4 specifically comprises the following steps:
(401) if the bus differential ring protection action occurs, the side switch dead zone fault occurs, the substation receives the side switch breaker jump position, and the main station monitors the side switch breaker to change the on position into the jump position through the substation; after a substation in a string where the side switch circuit breaker is located receives the jumping position of the side switch circuit breaker, the side switch locks a current sensor on the side of the circuit breaker, and the current of the current sensor on the side of the side switch circuit breaker is zero on the substation;
(402) if the bus differential ring protection action occurs, the side switch breaker fails to reject tripping, the string substation where the side switch breaker is located does not receive the tripping position of the breaker, and the main station does not receive the tripping position of the side switch breaker sent by the substation;
judging that the switch breaker fails while switching the breaker at the substation where the switch breaker is located, and rejecting tripping of the switch breaker while switching the breaker; the substation sends the tripping-resistant result of the side switch breaker to the main station;
the master station receives a side switch breaker protection action signal of bus differential protection and receives a side switch breaker bounce rejection signal sent by the substation;
the current transformer corresponding to the side switch breaker is blocked by the substation, the current sent to the side switch breaker of the main station is zero,
the main station of the station domain failure protection constructs differential current of a first line differential ring, and the differential current is out of limit;
(403) if the circuit protection action occurs, the side switch breaker fails and refuses to act; the main station receives a tripping command of the side switch breaker;
the sub-station locks the current sensor corresponding to the breaker, the current of the breaker sent to the main station is zero,
the main station of the station domain failure protection constructs differential current of a bus differential ring, and the differential current is out of limit;
(404) if the circuit protection action occurs, the open-close circuit breaker fails and refuses to act; the master station receives a command of tripping the open/close circuit breaker;
the current transformer corresponding to the open-close circuit breaker is blocked by the substation, the current of the open-close circuit breaker which is sent to the main station is zero,
and the main station for the station domain failure protection establishes the differential current of the differential ring of the second line, and the differential current is out of limit.
8. The method for fast isolating station domain failure protection of multiple direct current grid faults according to claim 3,
the differential ring protection criterion specifically comprises the following steps:
the master station of the station domain failure protection constructs differential current of a differential ring, the differential current is out of limit, and the failure protection of the differential ring is started; the differential ring has y branches, each branch having a current of IΦx(x ═ 1,2.. y), the differential current of the failure protection conventional proportional differential startup element of the differential loop is:
where Φ represents any one phase of three-phase current A, B, C, IdΦIn order to be a differential current flow,
a differential start threshold value;
the sudden change differential current of the failure protection sudden change proportional differential starting element of the differential ring is as follows:
wherein, Delta IdΦIn order to make the differential current of the amount of the mutation,
for differential start of threshold, Δ I, for sudden changesΦxThe current break quantity of the x branch is set;
the relation of logic OR is between the failure protection conventional proportional differential starting element and the failure protection sudden change proportional differential starting element;
the differential current, brake current and sudden change differential start thresholds of the differential loop fail-safe proportional differential element are:
wherein, IrΦFor braking current, IsetIs the threshold value of the differential current, and,
is a differential current action value, KrIs a conventional rate braking coefficient;
the differential current and the abrupt change differential current of the failure protection abrupt change proportional differential element of the differential ring are as follows:
wherein, Kr' is the braking coefficient of the mutation amount proportion; delta IrΦIs an abrupt change in differential current;
the failure protection proportional differential element and the failure protection abrupt variable proportional differential element are in an OR relationship.
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