CN111509673A - Method for preventing override trip of 110 KV and below power grid - Google Patents
Method for preventing override trip of 110 KV and below power grid Download PDFInfo
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- CN111509673A CN111509673A CN202010384999.XA CN202010384999A CN111509673A CN 111509673 A CN111509673 A CN 111509673A CN 202010384999 A CN202010384999 A CN 202010384999A CN 111509673 A CN111509673 A CN 111509673A
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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
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
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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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Abstract
The invention relates to a method for preventing override tripping of a power grid of 110 kilovolt or below, belonging to the technical field of safe operation management of the power grid containing a distributed power supply of 110 kilovolt or below. Through six steps of the invention, a current quick-break protection locking strategy of a power grid line containing a distributed power supply of 110 kilovolts or below is formulated, a circuit breaker is adopted by outgoing lines of a transformer substation, low-voltage and user branch switches, and a load switch is adopted by a main feeder cable and a switch with high insulation rate; setting the time limit difference of two-stage or multi-stage action of a breaker or a load switch according to the fault current characteristics; the method has the advantages that ordered control of the power grid is achieved, the power supply reliability of the power grid is improved, the operation is convenient, the override tripping risk rate of the power grid is reduced from the original 12% to the current 7%, and the problems that in the prior art, due to the fact that points are multiple and wide, the number of cascaded switches is large, branches are multiple, and the power supply radius is short, setting and matching of a protection device are difficult, and override tripping accidents cannot be prevented through local single control are solved.
Description
Technical Field
The invention relates to a method for preventing override tripping of a power grid of 110 kilovolt or below, belonging to the technical field of safe operation management of the power grid containing a distributed power supply of 110 kilovolt or below.
Background
With the rapid development of power grids containing distributed power supplies of 110 kv and below, the demand of 35 kv voltage class capacity is continuously increased, the condition that a plurality of 35 kv substations are supplied in series by one line is very common, and the condition of tripping from 10 kv faults to 35 kv is more and more, so that the risk of tripping from the transformer substations beyond 110 kv is also more and more. Once the 110 kv substation trips, all 35 kv substations serially connected with the 35 kv outgoing lines of the 110 kv substation are all subjected to voltage loss, so that a large amount of load and electric quantity loss is caused, even a seven-level power grid power failure accident is caused, and reliable power supply of 110 kv and below power grids and safe operation of the whole power grid are seriously influenced. The main reason for causing the override trip is that the time setting of the trip protection level difference of a power grid containing a distributed power supply of 110 kilovolts or below is unreasonable or the current constant value is unreasonable, and when a certain level of line on the lower line breaks down, the override trip is easily caused by chain reaction; moreover, the override trip covers a plurality of factors which are insufficient in technical management of power equipment, distributed power stations and personnel in each area, is multifaceted and wide, and is difficult to avoid the override trip through local single regulation and control. Therefore, it is necessary to research and design a method for preventing the override trip of the 110 kv and below power grids, which is particularly suitable for orderly controlling and implementing the 110 kv and below power grids in prefecture, city and county, has scientific procedure, convenient operation, feasibility and effectiveness, greatly reduces the override trip risk rate of the 110 kv and below power grids, and effectively improves the power supply reliability of the 110 kv and below power grids.
Disclosure of Invention
The invention aims to provide a method for preventing 110 KV and below power grid override tripping, which is particularly suitable for orderly controlling 110 KV and below power grids in prefecture, city and county, has scientific program, convenient operation, feasibility and effectiveness, greatly reduces the override tripping risk rate of the 110 KV and below power grids, reduces the override tripping risk rate of the power grids from the original 12% to the current 7%, and effectively improves the power supply reliability of the 110 KV and below power grids; the problem that the existing power grid containing a distributed power supply of 110 kilovolts or below is difficult to set and match due to the fact that the number of cascaded switches is large, the number of branches is large, the power supply radius is short, and the short-circuit current interval along the line is small, and the occurrence of the override trip accident cannot be prevented through local and single regulation and control is solved.
The invention realizes the purpose through the following technical scheme:
a method for preventing override tripping of 110 kv and the following grids, comprising: it comprises the following steps:
step one, comprehensively investigating and mastering power grids which have short power supply radius or more sections and contain distributed power supplies of 110 kilovolts or below in a district, and making a current quick-break protection locking strategy of power grid lines containing the distributed power supplies of 110 kilovolts or below;
step two, the implementation principle of the current quick-break protection locking strategy is to ensure that switches at all levels in each section of the jurisdiction are tripped reliably and quickly in order, namely the design is as follows: the switch closest to the fault position trips first, and meanwhile, locking information is sent to lock the upper-stage switch of the section; if the switch nearest to the fault position refuses tripping, the upper-stage switch nearest to the fault position is tripped through delay unlocking and locking, and the steps are sequentially carried out; the locking information is uploaded to the upper-level switch through optical fiber communication; the tripping circuit of each stage of high-voltage distribution device is connected in series with the short circuit locking normally closed contact of the next stage of high-voltage distribution device;
thirdly, all branch switches with high fault probability at the outgoing line side of the terminal substation, the low-voltage side of the transformer and the branch line of the user adopt circuit breakers, and all switches with high cabling and insulation rate and low fault probability of a main feeder line adopt load switches;
step four, setting the time limit difference of two-stage or multi-stage action of the circuit breaker or the load switch according to the fault current characteristics, and implementing current quick-break protection locking on a plurality of 35 kV and 10 kV bus side circuits of the 110 kV transformer, namely: setting the time difference of a current quick-break protection lock to be 0.6s, setting the time of a 35 kV quick-break limiting value to be 0.3s, and setting the 10 kV quick-break protection difference to be 0.1 s-0.2 s;
step five, a main feeder switch, except that any circuit incoming switch of the middle stage adopts a circuit breaker, all the rest adopt load switches; the time delay of the protection action of the user circuit breaker or the branch circuit breaker is set to be 0 s; the protection action delay time delta t of the outgoing line breaker of the transformer substation is set to be 200 ms-250 ms; the time delay of the protection action of the low-voltage side switch of the transformer is set to be 500ms or 300 ms;
step six, determining a matching principle of the stage difference of two-stage or multi-stage protection actions of a power grid containing 110 kilovolts of distributed power supplies and below; with three-stage motion involving three distributed power sourcesThe time limit level difference is taken as an example: the time limit difference of the three-stage action is designed as follows: the transformer substation outgoing switch, any one path of incoming switch of the middle-level ring main unit containing the distributed power supply and the outgoing switch of the middle-level ring main unit containing the distributed power supply form three-level differential protection by adopting circuit breakers, and the rest switches adopt load switches, so that the switch configuration cost is reduced; b containing distributed power supply1~B12The action time of an outgoing line breaker of the intermediate ring main unit is set to be 0 second; comprising a distributed power supply A4The action time of any one-path incoming line breaker of the intermediate ring main unit is set to be delta t seconds; the action time of the outgoing line breaker of the transformer substation is set to be 2 delta t, and the delta t is set to be 200 ms-250 ms.
Compared with the prior art, the invention has the beneficial effects that:
according to the method for preventing the override trip of the power grid of 110 kilovolts or below, ordered management and control of the power grid containing the distributed power supply of 110 kilovolts or below are realized by six steps of formulating and implementing a current quick-break protection locking strategy of the line of the power grid of the distributed power supply of 110 kilovolts or below, branch switches with high fault probability of the outgoing line side of a terminal substation, the low-voltage side of a transformer and user branch lines are all provided with circuit breakers, and switches with high main feeder cabling and insulation rate and low fault probability are all provided with load switches; setting the time limit difference of two-stage or multi-stage action of a breaker or a load switch according to the fault current characteristics, setting the time difference of a current quick-break protection lock to be 0.6s, setting the time of a 35 kV quick-break limiting value to be 0.3s, and setting the 10 kV quick-break protection difference to be 0.1 s-0.2 s; the method has the advantages of scientific program, convenient operation, strong practicability and effectiveness, greatly reduces the override trip risk rate of the power grid of 110 kilovolt and below, reduces the override trip risk rate of the power grid from the original 12% to the current 7%, effectively improves the power supply reliability of the power grid of 110 kilovolt and below, and is particularly suitable for orderly management and control operation of the power grids of 110 kilovolt and below in prefecture and county. The problems that the conventional power grid containing a distributed power supply of 110 kilovolts or below is multi-faceted and wide, the number of cascaded switches is large, the number of branches is large, the power supply radius is short, short-circuit current intervals along the line are small, setting and matching of a protection device are difficult, and the occurrence of an override trip accident cannot be prevented through local and single regulation and control are solved.
Drawings
FIG. 1 is a schematic flow chart of the operation of a current snap-off protection lockout strategy for a method of preventing override trips to a power grid of 110 kV and below;
FIG. 2 is a schematic diagram of the operating principle of a plurality of 35 kV and 10 kV bus-side lines of a 110 kV transformer for a method of preventing override tripping of 110 kV and below grids using a current quick-break protection lockout strategy;
fig. 3 is a schematic diagram of the working principle of the three-stage action time limit difference with three distributed power sources of the method for preventing 110 kv and below power grid override tripping by adopting a current quick-break protection blocking strategy.
In the figure:
k1 is a set short-circuit point;
s1 and S2 are substation outgoing line breakers;
A1-A3 and A5-A8 are main line/feeder line load switches;
a4 is a branch breaker;
B1-B12 are feeder/user/branch breakers;
DC 1-DC 3 are distributed power supplies;
d1 is the short circuit point set between B4 and DC 2.
Detailed Description
Embodiments of the method for preventing override tripping of 110 kv and the following grids are described in further detail below with reference to the accompanying drawings (see fig. 1 to 3):
a method for preventing override tripping of 110 kv and the following grids, comprising: it comprises the following steps:
step one, comprehensively investigating and mastering power grids with short power supply radius or more sections and containing distributed power supplies of 110 kilovolts or below in a district, and making a current quick-break protection locking strategy (shown in figure 1) of power grid lines containing the distributed power supplies of 110 kilovolts or below;
step two, the implementation principle of the current quick-break protection locking strategy is (as shown in fig. 2) -the orderly, reliable and quick tripping of each stage of switches in each district is ensured, namely the design: the switch closest to the fault position trips first, and meanwhile, locking information is sent to lock the upper-stage switch of the section; if the switch closest to the fault position refuses tripping, unlocking and locking through time delay (the time delay amount is shown in the step four and the step five), so that the upper-stage switch closest to the fault position trips, and the steps are sequentially carried out; the locking information is uploaded to the upper-level switch through optical fiber communication; the tripping loop of each stage of high-voltage distribution device is connected with the short circuit locking normally closed contact of the next stage of high-voltage distribution device in series;
thirdly, all branch switches with high fault probability at the outgoing line side of the terminal substation, the low-voltage side of the transformer and the branch line of the user adopt circuit breakers, and all switches with high cabling and insulation rate and low fault probability of a main feeder line adopt load switches;
step four, setting the time limit difference of two-stage or multi-stage action of the circuit breaker or the load switch according to the fault current characteristics, and implementing current quick-break protection locking on a plurality of 35 kV and 10 kV bus side circuits of the 110 kV transformer, namely: setting the time difference of a current quick-break protection lock to be 0.6s, setting the time of a 35 kV quick-break limiting value to be 0.3s, and setting the 10 kV quick-break protection difference to be 0.1 s-0.2 s;
step five, a main feeder switch, except that any circuit incoming switch of the middle stage adopts a circuit breaker, all the rest adopt load switches; the time delay of the protection action of the user circuit breaker or the branch circuit breaker is set to be 0 s; the protection action delay time delta t of the outgoing line breaker of the transformer substation is set to be 200 ms-250 ms; the time delay of the protection action of the low-voltage side switch of the transformer is set to be 500ms or 300 ms;
step six, determining a matching principle of the stage difference of two-stage or multi-stage protection actions of a power grid containing 110 kilovolts of distributed power supplies and below; taking the three-level time-limited difference of the three distributed power sources as an example (as shown in fig. 3): the time limit difference of the three-stage action is designed as follows: the transformer substation outgoing switch, any one path of incoming switch of the middle-level ring main unit containing the distributed power supply and the outgoing switch of the middle-level ring main unit containing the distributed power supply form three-level differential protection by adopting circuit breakers, and the rest switches adopt load switches, so that the switch configuration cost is reduced; involving distributed power sourcesB of (A)1~B12The action time of an outgoing line breaker of the intermediate ring main unit is set to be 0 second; comprising a distributed power supply A4The action time of any one-path incoming line breaker of the intermediate ring main unit is set to be delta t seconds; the action time of the outgoing line breaker of the transformer substation is set to be 2 delta t, and the delta t is set to be 200 ms-250 ms.
Example 1 (taking a 10 kv bus or a feeder thereof with a short-circuit fault as an example):
the specific implementation action flow (as shown in fig. 1) of the line current quick-break protection locking strategy is that optical fiber communication is adopted between an upper 110 kv substation 1 and a lower 35 kv substation 1, and each breaker is provided with a matched breaker controller for collecting short-circuit current and uploading a locking signal to control the action of the corresponding breaker. If a short-circuit fault occurs to a 10 kilovolt bus or a feeder line thereof, the position K1 is short-circuited (as shown in figure 2), the 10 kilovolt bus or 380 volt load feeder line at the next stage cannot detect short-circuit current, a locking signal cannot be sent to a 10 kilovolt bus circuit breaker, the 10 kilovolt bus circuit breaker detects short-circuit current, if the short-circuit current exceeds a setting value, the 10 kilovolt bus circuit breaker trips, meanwhile, a locking signal is sent to a 35 kilovolt transformer substation 1 circuit breaker at the upper stage, a 35 kilovolt transformer substation 1 circuit breaker tripping loop is disconnected, a corresponding circuit breaker is locked, and the locking of the 35 kilovolt transformer substation 1 circuit; and if the 10 kV bus circuit breaker fails to operate, the circuit breaker of the upper 35 kV substation 1 is unlocked after the step difference delay, and the circuit breaker of the 35 kV substation 1 trips, so that override tripping is prevented. (as shown in FIG. 2), n is a positive integer of 1, 2, 3, 4 ….
Example 2 (taking the example with three distributed power sources):
a power grid containing three distributed power supplies of 110 kilovolts and below (as shown in fig. 3); the transformer substation outgoing switch, any one path of incoming switch of the middle-level ring network containing the distributed power supply and the outgoing switch of the middle-level ring network cabinet containing the distributed power supply form three-level differential protection by adopting circuit breakers, and the rest switches adopt load switches, so that the switch configuration cost can be reduced; (as shown in FIG. 3), B1~B12Action of outlet circuit breaker of intermediate ring main unit (with distributed power supply)Time is set to 0 second; a. the4The action time of any one-path incoming line breaker of the intermediate ring main unit (containing a distributed power supply) is set to be delta t seconds; the action time of the outgoing line breaker of the transformer substation is set to be 2 delta t, and the delta t is 200 ms-250 ms; the time delay of the protection action of the low-voltage side switch of the transformer is set to be 500ms or 300 ms. (as shown in FIG. 3), if d1 (B)4And DC2Feeder lines) and is larger than a setting value, the breaker B4 detects the tripping of short-circuit current, sends information to remotely control the tripping of A3, B5 and B6, and restores the substation outgoing line breaker S1 to close and isolate a fault line. Therefore, the override trip accidents caused by line faults and poor management of the power grid containing the distributed power supply of 110 kilovolts or below are greatly reduced.
In practical application, according to the six steps of the method for preventing the override trip of the power grid of 110 kilovolt and below, the current quick-break protection locking strategy containing the distributed power supply of 110 kilovolt and below power grid lines is operated and implemented, the level difference configuration and the switch configuration are adjusted, the ordered control of the power grid of 110 kilovolt and below is realized, the override trip risk rate of the power grid of 110 kilovolt and below is reduced from the original 12 percent to the current 7 percent, and the power supply reliability of the power grid of 110 kilovolt and below is practically ensured.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (1)
1. A method for preventing override tripping of 110 kv and the following grids, comprising: it comprises the following steps:
step one, comprehensively investigating and mastering power grids which have short power supply radius or more sections and contain distributed power supplies of 110 kilovolts or below in a district, and making a current quick-break protection locking strategy of power grid lines containing the distributed power supplies of 110 kilovolts or below;
step two, the implementation principle of the current quick-break protection locking strategy is to ensure that switches at all levels in each section of the jurisdiction are tripped reliably and quickly in order, namely the design is as follows: the switch closest to the fault position trips first, and meanwhile, locking information is sent to lock the upper-stage switch of the section; if the switch nearest to the fault position refuses tripping, the upper-stage switch nearest to the fault position is tripped through delay unlocking and locking, and the steps are sequentially carried out; the locking information is uploaded to the upper-level switch through optical fiber communication; the tripping circuit of each stage of high-voltage distribution device is connected in series with the short circuit locking normally closed contact of the next stage of high-voltage distribution device;
thirdly, all branch switches with high fault probability at the outgoing line side of the terminal substation, the low-voltage side of the transformer and the branch line of the user adopt circuit breakers, and all switches with high cabling and insulation rate and low fault probability of a main feeder line adopt load switches;
step four, setting the time limit difference of two-stage or multi-stage action of the circuit breaker or the load switch according to the fault current characteristics, and implementing current quick-break protection locking on a plurality of 35 kV and 10 kV bus side circuits of the 110 kV transformer, namely: setting the time difference of a current quick-break protection lock to be 0.6s, setting the time of a 35 kV quick-break limiting value to be 0.3s, and setting the 10 kV quick-break protection difference to be 0.1 s-0.2 s;
step five, a main feeder switch, except that any circuit incoming switch of the middle stage adopts a circuit breaker, all the rest adopt load switches; the time delay of the protection action of the user circuit breaker or the branch circuit breaker is set to be 0 s; the protection action delay time delta t of the outgoing line breaker of the transformer substation is set to be 200 ms-250 ms; the time delay of the protection action of the low-voltage side switch of the transformer is set to be 500ms or 300 ms;
step six, determining a matching principle of the stage difference of two-stage or multi-stage protection actions of a power grid containing 110 kilovolts of distributed power supplies and below; taking the three-level operation time limit difference containing three distributed power sources as an example: the time limit difference of the three-stage action is designed as follows: substation outgoing switch, intermediate ring main unit arbitrary incoming switch with distributed power supply and intermediate ring main unit with distributed power supplyThe outgoing switches of the middle-stage ring main unit of the distributed power supply adopt circuit breakers to form three-stage differential protection, and the rest switches adopt load switches, so that the switch configuration cost is reduced; b containing distributed power supply1~B12The action time of an outgoing line breaker of the intermediate ring main unit is set to be 0 second; comprising a distributed power supply A4The action time of any one-path incoming line breaker of the intermediate ring main unit is set to be delta t seconds; the action time of the outgoing line breaker of the transformer substation is set to be 2 delta t, and the delta t is set to be 200 ms-250 ms.
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Cited By (2)
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CN113258545A (en) * | 2021-04-14 | 2021-08-13 | 珠海许继电气有限公司 | In-situ feeder automation method and system based on multi-stage time step difference protection |
CN113541109A (en) * | 2021-07-02 | 2021-10-22 | 国网浙江省电力有限公司金华供电公司 | Feeder fault processing system and method based on power wireless private network |
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CN113541109A (en) * | 2021-07-02 | 2021-10-22 | 国网浙江省电力有限公司金华供电公司 | Feeder fault processing system and method based on power wireless private network |
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