CN111711176A - Station domain protection method suitable for short-circuit current exceeding scene - Google Patents
Station domain protection method suitable for short-circuit current exceeding scene Download PDFInfo
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- CN111711176A CN111711176A CN202010490727.8A CN202010490727A CN111711176A CN 111711176 A CN111711176 A CN 111711176A CN 202010490727 A CN202010490727 A CN 202010490727A CN 111711176 A CN111711176 A CN 111711176A
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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 discloses a station domain protection method suitable for a short-circuit current exceeding scene. The technical scheme of the invention is as follows: the station domain protection device calculates the current amplitude of each branch circuit and the bus branch circuit breaker within 5ms after the fault, and if the current amplitude of the fault outgoing line is larger than the breaking capacity of the circuit breaker, the bus branch circuit breaker is tripped out; when the fault occurs 30ms later, the station area protection device calculates the current amplitude of the fault outgoing line again, if the current amplitude of the fault outgoing line is smaller than the breaking capacity of the breaker, the breaker of the fault outgoing line is tripped, and otherwise, the next step is carried out; and the station area protection device sequentially trips the non-fault branch circuit breakers with the largest current according to the current amplitude until the current of the fault outgoing line is smaller than the breaking capacity of the circuit breaker, and then trips the circuit breaker of the fault outgoing line. According to the invention, through the information sharing of the substation area in the transformer substation and the optimization of the protection action logic, the fault current is quickly cut off in the scene that the short-circuit current exceeds the standard.
Description
Technical Field
The invention relates to the field of electric power, in particular to a station domain protection method suitable for a short-circuit current exceeding standard scene.
Background
With the continuous enlargement of the scale of the power system and the increasing strengthening of the grid structure, the level of short-circuit current in the power system rises year by year, and the short-circuit current of 220kV and 500kV buses exceeds 50kA, even approaches 63 kA. If the fault current exceeds the breaking capacity of the circuit breaker, catastrophic consequences such as circuit breaker failure, expanded protection cutting range and the like can occur. The exceeding of the short-circuit current is a significant problem in planning, designing and operating the power system.
Aiming at the development of a power grid, the current method for limiting the short-circuit current mainly comprises two main types of devices for adjusting the operation mode of a system and limiting the short-circuit current by adopting high impedance. The operation modes of the adjusting system comprise 220kV double-bus split operation, out-of-line operation in a 500kV 3/2 wiring mode, machine set accompanying stop, pull-out circuit and the like, and the methods limit short-circuit current and reduce the flexibility and safety margin of power grid operation. The method for adopting the high-impedance short-circuit current limiting equipment mainly comprises the steps of serially connecting a current-limiting reactor, increasing the impedance of a transformer and a generator and the like, and the method increases the reactive loss and the voltage loss of a system while increasing the impedance of a fault loop and limiting the short-circuit current, and needs to be configured with additional reactive compensation equipment.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a station domain protection method suitable for a short-circuit current exceeding scene, which realizes the rapid removal of fault current in the short-circuit current exceeding scene through the sharing of station domain information in a transformer substation and the optimization of protection action logic.
The technical scheme adopted by the invention is as follows: a station domain protection method suitable for a scene that short-circuit current exceeds standard is characterized in that a bus branch breaker capable of removing faults within 20ms is installed at a bus branch of a 220kV double-bus substation, the bus branch breaker is switched on during normal operation, double buses are in closed loop operation, and a station domain protection device is configured to collect currents of all branches and the bus branch breaker in the substation; after the fault occurs, the action logic of the station domain protection device comprises:
step 1: when a 220kV substation outgoing line has a short-circuit fault, the station domain protection device calculates the current amplitude of each branch circuit and the bus branch circuit breaker within 5ms after the fault; if the fault outgoing line current amplitude is larger than the breaking capacity of the breaker, the bus branch breaker is tripped off firstly, so that short-circuit current fed in at a fault point is reduced; if the current amplitude of the fault outgoing line is smaller than the breaking capacity of the breaker, directly tripping off the breaker of the fault outgoing line to realize fault isolation;
step 2: when the station area protection device is 30ms after the fault (waits for the bus branch breaker to open), the current amplitude of the fault outgoing line is calculated again, and if the current amplitude of the fault outgoing line is smaller than the breaking capacity of the breaker, the breaker of the fault outgoing line is tripped off, so that the fault isolation is realized; if the current amplitude of the fault outgoing line is still larger than the breaking capacity of the breaker at the moment, entering step 3;
and step 3: the station area protection device calculates the current amplitude of each branch circuit again, trips the non-fault branch circuit breaker with the maximum current, and judges whether the fault outgoing current is larger than the breaking capacity of the circuit breaker after delaying for 50ms (waiting for the branch circuit breaker to be opened), and if the fault outgoing current is smaller than the breaking capacity of the circuit breaker, the station area protection device trips the circuit breaker of the fault outgoing line to realize the complete isolation of the fault; and if the fault outgoing line current is still larger than the breaking capacity of the circuit breaker, the station area protection device continues to cut off the non-fault branch circuit breaker with the maximum current until the fault outgoing line current is smaller than the breaking capacity of the circuit breaker.
Further, in the step 1, the station domain protection device collects the current amplitudes of all the branches and the bus branch circuit breakers, and extracts the current amplitudes within 5ms through a least square algorithm.
Further, in step 2, the station domain protection device recalculates the fault current amplitude by using the current sampling data within 25ms to 30ms after the fault, and the algorithm adopts a least square algorithm.
Further, the equation for calculating the current amplitude by the least squares algorithm is:
in the formula: i isfmThe current amplitude to be solved; y (n) ═ if(1) if(2) ... if(N)]TY (N) is a fault current sampling sequence, if(1)、if(2)、…、if(i)、…、if(N) is a sampling value of N fault currents obtained after 5ms of fault; x (n) ═ X1X2X3X4]T，X1、X2、X3、X4X (N) is a parameter vector to be identified; h (n) ([ h (1) h (2).. h (i).. h (n))]H (n) is an input-output matrix, where h (i) ═ 1 i Δ tssin[(ω)iΔts]cos[(ω)iΔts]}，ΔtsIs the sampling period of the data, i is the sampling orderAnd the serial number and omega are equal to the angular speed 100 pi rad/s corresponding to the power frequency.
Further, in step 3, the station area protection device sequentially cuts off the circuit breakers of the non-fault branches from large to small according to the calculated current amplitude of each branch until the current amplitude of the fault outgoing line is smaller than the breaking capacity of the circuit breaker.
The invention has the following beneficial effects: according to the invention, on the premise of not damaging the original operation mode of the system and not increasing the current-limiting reactance, the fault current is quickly cut off in the scene that the short-circuit current exceeds the standard through the information sharing of the substation area in the transformer substation and the optimization of the protection action logic.
Drawings
The invention is described in further detail below with reference to the figures and the detailed description of the invention.
Fig. 1 is a configuration diagram of relay protection of a 220kV double-bus substation in an embodiment of the present invention;
FIG. 2 is a graph of the distribution of short circuit current after an out-of-line fault in an embodiment of the present invention;
FIG. 3 is a schematic diagram of a post fault parent disconnect in accordance with an embodiment of the present invention;
fig. 4 is a schematic diagram of a non-fault branch circuit breaker (power supply 2 branch circuit breaker) with the maximum current amplitude value being tripped again after the bus branch circuit breaker is disconnected in the embodiment of the present invention, if the current amplitude value of the fault outgoing line is still greater than the breaking capacity of the circuit breaker;
fig. 5 is a schematic diagram of the breaker tripping the fault outlet after the second power branch breaker is opened, wherein the current amplitude of the fault outlet is smaller than the breaking capacity of the breaker;
FIG. 6 is a logic diagram of a protection action in accordance with an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
As shown in FIG. 1, during the normal operation of a 220kV double-bus substation, a bus-disconnecting circuit breaker is switched on, and a double-bus loop is closed to operate. And the configuration station domain protection device acquires the current of each branch and the bus branch circuit breaker in the transformer substation.
After the first outlet fault occurs, the distribution of the fault current is as shown in fig. 2. The short-circuit current fed into the first outgoing line side respectively comes from the first power supply, the second power supply and the third power supply, wherein the short-circuit current fed into the first power supply flows through the bus branch circuit breaker.
Step 1: when a 220kV substation outgoing line has a short-circuit fault, the station domain protection device calculates the current amplitude of each branch circuit and the bus branch circuit breaker within 5ms after the fault. At this time, the amplitude of the fault outlet current is greater than the breaking capacity of the circuit breaker, so that the bus branch circuit breaker is tripped first, thereby reducing the short-circuit current fed in at the fault point, as shown in fig. 3.
Step 2: and (3) when the station domain protection device is 30ms after the fault (waits for the master switch breaker to open), calculating the current amplitude of the fault outgoing line again, wherein the current amplitude of the fault outgoing line is still larger than the breaking capacity of the breaker due to the fact that the master switch breaker is not successfully opened at the moment, and then the step is carried out.
And step 3: the station area protection device calculates the current amplitude of each branch circuit again, and trips the non-fault branch circuit breaker with the maximum current, namely, the circuit breaker corresponding to the branch circuit of the power supply 2, so as to further reduce the short-circuit current fed in by the fault outgoing line, as shown in fig. 4. After delaying 50ms (waiting for the branch circuit breaker to open), judging that the fault outgoing line current is smaller than the breaking capacity of the breaker, tripping off the breaker of the fault outgoing line to realize complete fault isolation, as shown in fig. 5.
The action logic of the station domain protection device is shown in figure 6.
Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (5)
1. A station domain protection method suitable for a scene that short-circuit current exceeds standard is characterized in that a bus branch breaker capable of removing faults within 20ms is installed at a bus branch of a 220kV double-bus substation, the bus branch breaker is switched on during normal operation, double buses are in closed loop operation, and a station domain protection device is configured to collect currents of all branches and the bus branch breaker in the substation; the method is characterized in that after the fault occurs, the action logic of the station domain protection device comprises the following steps:
step 1: when a 220kV substation outgoing line has a short-circuit fault, the station domain protection device calculates the current amplitude of each branch circuit and the bus branch circuit breaker within 5ms after the fault; if the fault outgoing line current amplitude is larger than the breaking capacity of the breaker, tripping off the bus branch breaker, and reducing the short-circuit current fed in at the fault point; if the current amplitude of the fault outgoing line is smaller than the breaking capacity of the breaker, the breaker of the fault outgoing line is directly tripped off to realize fault isolation;
step 2: when the station area protection device is 30ms after the fault, the current amplitude of the fault outgoing line is calculated again, and if the current amplitude of the fault outgoing line is smaller than the breaking capacity of the breaker, the breaker of the fault outgoing line is tripped out, so that the fault isolation is realized; if the current amplitude of the fault outgoing line is still larger than the breaking capacity of the breaker at the moment, entering step 3;
and step 3: the station area protection device calculates the current amplitude of each branch circuit again, trips the non-fault branch circuit breaker with the largest current, and judges whether the fault outlet current is larger than the breaking capacity of the circuit breaker after delaying for 50ms, if the fault outlet current is smaller than the breaking capacity of the circuit breaker, the station area protection device trips the circuit breaker with the fault outlet to realize the thorough isolation of the fault; and if the fault outgoing line current is still larger than the breaking capacity of the circuit breaker, the station area protection device continues to cut off the non-fault branch circuit breaker with the maximum current until the fault outgoing line current is smaller than the breaking capacity of the circuit breaker.
2. The station domain protection method suitable for the scene that the short-circuit current exceeds the standard according to claim 1, wherein in the step 1, the station domain protection device collects the current amplitudes of each branch circuit and the bus branch circuit breaker, and extracts the current amplitudes within 5ms through a least square algorithm.
3. The station domain protection method adapting to the short-circuit current exceeding scene as claimed in claim 1, wherein in step 2, the station domain protection device uses the current sampling data within 25ms to 30ms after the fault to recalculate the fault current amplitude, and the algorithm adopts least square algorithm.
4. The station domain protection method suitable for the short-circuit current exceeding scene according to claim 2 or 3, wherein the equation for calculating the current amplitude by the least square algorithm is as follows:
in the formula: i isfmThe current amplitude to be solved; y (n) ═ if(1) if(2)...if(N)]TY (N) is a fault current sampling sequence, if(1)、if(2)、…、if(i)、…、if(N) is a sampling value of N fault currents obtained after 5ms of fault; x (n) ═ X1X2X3X4]TX (N) is a parameter vector to be identified, X1、X2、X3、X4Is a parameter to be identified; h (n) ([ h (1) h (2).. h (i).. h (n))]H (n) is an input-output matrix, where h (i) ═ 1 i Δ tssin[(ω)iΔts]cos[(ω)iΔts]}，ΔtsAnd (3) as a sampling period of data, i is a sampling sequence number, and omega is equal to the angular speed 100 pi rad/s corresponding to the power frequency.
5. The station domain protection method suitable for the scenario that the short-circuit current exceeds the standard according to claim 1, wherein in step 3, the station domain protection device sequentially cuts off the circuit breakers of the non-fault branches from large to small according to the calculated current amplitude of each branch until the current amplitude of the fault outgoing line is smaller than the breaking capacity of the circuit breaker.
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| CN202010490727.8A CN111711176B (en) | 2020-06-02 | 2020-06-02 | Station domain protection method suitable for short-circuit current exceeding scene |
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| CN202010490727.8A CN111711176B (en) | 2020-06-02 | 2020-06-02 | Station domain protection method suitable for short-circuit current exceeding scene |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113241742A (en) * | 2021-05-26 | 2021-08-10 | 广东电网有限责任公司 | Intelligent substation fault removal method and device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5467241A (en) * | 1991-01-28 | 1995-11-14 | Hitachi, Ltd. | Power receiving system |
| US20130027829A1 (en) * | 2011-07-28 | 2013-01-31 | Abb S.P.A. | System and method for protecting an electrical grid against faults |
| CN103414173A (en) * | 2013-09-02 | 2013-11-27 | 国家电网公司 | Method for performing fault recovery on power distribution network based on ultra-short term load |
| CN107895940A (en) * | 2017-10-30 | 2018-04-10 | 国家电网公司 | A kind of method for limiting transformer station's 220KV short circuit currents |
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2020
- 2020-06-02 CN CN202010490727.8A patent/CN111711176B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5467241A (en) * | 1991-01-28 | 1995-11-14 | Hitachi, Ltd. | Power receiving system |
| US20130027829A1 (en) * | 2011-07-28 | 2013-01-31 | Abb S.P.A. | System and method for protecting an electrical grid against faults |
| CN103414173A (en) * | 2013-09-02 | 2013-11-27 | 国家电网公司 | Method for performing fault recovery on power distribution network based on ultra-short term load |
| CN107895940A (en) * | 2017-10-30 | 2018-04-10 | 国家电网公司 | A kind of method for limiting transformer station's 220KV short circuit currents |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113241742A (en) * | 2021-05-26 | 2021-08-10 | 广东电网有限责任公司 | Intelligent substation fault removal method and device |
| CN113241742B (en) * | 2021-05-26 | 2023-01-20 | 广东电网有限责任公司 | Intelligent substation fault removal method and device |
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